ACI352R-91(Reapproved 1997) Recommendations for Design of Beam-Column Joints in Monolithic Reinforced Concrete Structures Reported by ACI-ASCE Committee 352 Clarkson W. Pinkham Norman W. Hanson Chairman Secretary James K. Wight Subcommtttee Chairman J. D. Artstizibal David A. Hunter Mehdi Saiidi Vitelmo V. Bertcro James 0. Jima Donald R. Strand Marvin E. Criswell Cary Kopczynski S. M. Uzumeri Ahmad J. Durram Donald F. Meinheit Sudhakar P. Verma Mohammad R. Ehsani John J. Otrembiak Lormg A. Wyllie, Jr. Edward S. Hoffman Robert Park Liandc Zhang Committee members voting on the 1991 revisions: James K. Wight Mohammad R. Ehsani Chairman Secretary Ahmad J. Durrani Chairman, Editorial Subcommittee James R. Cagley Donald F. Meinheit Gene R. Stevens Marvin E. Criswell Jack P. Moehle Donald R. Strand Luis E. Garcia Clarkson W. Pinkham S. M. Uzumeri Cary S. Kopczynski Mehdi Saiidt Sudhakar P. Verma Michael E. Kreger Mustafa Seckin Loring A. Wyllie, Jr. These recommendations an a revision of earlier recommendations from concrete; connections; earthquake resistant structures; hooked reinforce- this committee. Recommendations are given for member proportions and ment; joints (junctions); reinforced concrete; reinforcmg steels; shear reinforcement dctaiL requind for satisfactory confiement of the column strength; stresses; structural design; structures. core i n the joint region. adequate joint shear strength, the proper ratio of column-moment strength versus beam-moment strength at the joint, and CONTENTS development of reinforcing bars either terminating in or passing through the joint. Commentary is provided to amplify the recommendations and Chapter l-Introduction and scope, p. 352R-2 identify available reference material. 1. l-Introduction The recommendations are based on laboratory testing as well as field 1.2-Scope for concrete studies and provide a state-of-the-art summary of current information. Amas needing research aw identified. Design examples are presented to 1.3-Scope for Type 2 joints illustrate the USC of the design ncommcndations. Chapter 2-Classification of beam-column joints, p. Keywords: beam-column joints, anchorage (structural); beams (sup- 352R-2 porta); bond (concrete to reinforcement); columns (supports); confined 2. l-General AC1 Commtttee Reports, Gurdes, Standard Practtces, and Commentarms 2.2~Definition ate intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its con- tent and recommendations and who will accept responsibility for the AC1 352R-91 became effectwe June I. 1991 and vqer\ede\ ACI 152R-85 Numer- application of the material it contains. The American Concrete Institute out edmwal and m~ncr nw,\,cm\ were made to the report Reference\ have teen disclaims any and all responsibility for the stated principles. The Institute added and updated Copyrnght 8 1997, Amencan Concrete InWute shall not be liable for any loss or damage arising therefrom. All right\ raewedmcludmg rights of reproduction and w e !nany form or by any Reference to this document shall not be made in contract documents. If means. mcludmg the makmg of copes by any photo proce\\, or by electrow or items found in this document are desired by the Architect/Engineer to be mechanical &we, printed. written. or oral, or recordmg for wund or w\uaI reproduc- a part of the contract documents, they shall be restated in mandatory lan- tmn or for u\e I” any knowledge or retrieval \y\tem or dewce. unle\\ perm,\\mn ,n guage for incorporation by the Architect/Engineer. wrung IF obtanud from the copyright proprietor+ -________ -..-.A 352R-1 352R-2 MANUAL OF CONCRETE PRACTICE This report considers typical beam-column joints in cast- in-place reinforced concrete structures, as shown in Fig. 1.1. Specifically excluded from these recommendations are slab- column joints and precast structures where connections are made near the beam-to-column intersection. Design exam- ples illustrating the use of these recommendations are given in Appendix B. The material presented here is an update of a previous re- port from ACI-ASCE Committee 352.49 A partial listing of (a) Exterior (b) Interior research information available to the committee at that time is given in References l-38. Research information available ‘Fig. I.l-Typical beam-to-column connections in References 39-66 and Chapter 2 1 of AC1 3 18 have been received during the updating of these provisions. This report Chapter 3-Design considerations, p. 352R-3 addresses joints in both seismic and nonseismic regions, 3. l-Critical sections whereas Chapter 2 1 of AC1 3 18 addresses only joints in seis- 3.2-Forces mic regions. 3.3-Serviceability 3.4-Strength considerations l&-Scope for concrete These recommendations apply only to structures using Chapter A--Nominal strength considerations, p. 35214 normal weight concrete in the joints. 4. I-Compression 4.2-Transverse reinforcement 1.3-4cope for Type 2 joints 4.3~Shear for Type 1 and Type 2 joints For Type 2 joints as defined in Section 2.1, only joints in 4.4-Flexure which the column width is equal to or greater than the beam 4.5-Development of reinforcement width are covered by these recommendations. For Type 2 joints, the recommendations provide guidance Chapter 5-Notation, p. 352R-9 only in cases where the beam bars are located within the col- umn core. All currently available research results are for Chapter &References, p. 352R-10 connections where the beam width is less than or equal to the column width and the beam centerline passes through rhe Appendix A-Areas needing research, p. 352R-12 column centroid. Connecrions where the beam centerline does norpass through the column centroid are included ifall Appendix B-Design examples, p, 3521-13 beam bars are anchored in or pass through rhe column core. However, the torsion resulting from this eccentricity should CHAPTER l-INTRODUCTION AND SCOPE* be considered. Connections where the beam bars pass out- side the column core are excluded for Type 2 joints because l.l-Introduction of a lack of research data on rhe anchorage of such bars un- These recommendations are for determining joint propor- der large load reversals. tions and design of the longitudinal and transverse reinforce- ment at the intersection of beams and columns in cast-in- CHAPTJXR 2-CLASSIFICATION OF place concrete frame construction. The recommendations BEAM-COLUMN JOINTS are written to satisfy strength and ductility requirements re- lated to the function of the joint, 2.1-General In the past, the design of joints in monolirhic reinforced Structural joints are classified into two categories, Type 1 concrete srrucrures was primarily limited to satisfying an- and Type 2, based on the loading conditions for the joint and chorage requirements for rhe reinforcement. Because of the the anticipated deformations of the joint when resisting lat- use of high-strength materials (concrete and steel), smaller eral loads. member sections, and larger reinforcing bars, special atten- 2.1.1 Type I - A Type 1 joint connects members de- tion to rhe design and detailing of the joint has become more signed to satisfy AC1 318 strength requirements and in important. In many designs, column sizes may be defined by which no significant inelastic deformations are anticipated. the requirements of joint detail design. Attention is focused 2.1.2 Type 2 - A Type 2 joint connects members desig- on the joint to ensure proper structural performance under nated to have sustained strength under deformation reversals all loading conditions that may reasonably be expec&d lo into the inelastic range. occur and to alert the designer to possible congestion of re- The requirements forjoints are dependent on the deforma- inforcement. tions at the joint implied by rhe design loading conditions. Typical examples of each joint type are: Type 1 is a joint in a continuous moment resisting struc- *Design recommendations of Committee 352 are set in standard type: commentary and explanations follow each section in italic type. ture designed on the basis of strength without considering 2. torsion. .1(a)]. the columns are assumed to be at their flexural capacities. subscript b for beam and column. search studyS demonstrates typical laboratory results for a duce the most severe force distribution at the joint. their capacities before the beam sections.3-Serviceability ber-joint interfaces should be determined using the stress a& Cracking and concentrated rotation are to be expected near where fy is the specified yield strength of the reinforcing bars the joint faces where bending moments usually reach their and a is a stress multiplier maximum values. The factor a is intended to account for the following: (a) These forces are a consequence of the effects of externally the actual yield stress of a typical reinforcing bar is com- applied loads as well as those resulting from creep. 3. Exceptions are made for joint shear and reinforcement librium. Strength reduction report. consideration should be given to de. a value of a larger than the termine which members will reach initial flexural yielding recommended minimum may be appropriate.2 at the critical sections. and age. including the slab.1. or settlement. A re- by adjacent members.1-The joint should be designed for the interaction of moments and shears have magnitudes required to keep the the multidirectional forces which the members transfer to the joint in equilibrium. and secondary effects.1-Critical sections A beam-column joint should be profirtioned to resist the The analysis of the forces acting on a Type 1 or Type 2 forces specified in Section 3. the anchorage. same approach is used unless the column sections reach es acting on the critical sections.I-Planarjointforces. 3. bending. subscript c for column CHAPTER 3-DESIGN CONSIDERATIONS ForType a.2. For Type 2 joints the stress attributable to strain hardening when plastic hinging design forces that the members transfer to the joint are not occurs. that frame into the pression force. T = tension force. but should be determinedfrom the nominal strengths of to this type of joint. the forces in Fig. ties are not controlled properly.0 3 18 for cracking and deflection under service loads. mum for Type 2 joints. lateral loads. Fig.” a value of a = 1.3. and the design forces in the flexural reinforcement at the mem. As pointed out in the previous committee the members as defined in Section 3. Forces produced by discussed in detail in a previous committee report” show a deformations resultingftom time-dependent effects and tem. The corresponding column Design recommendations are based on the assumption forces are then a function of the column axial load and the that the critical sections are immediately adjacent to the moments and shears required to keep the connection in equi- joint. and the beam 3.0 is permitted for Type I joints be- limited to the forces determinedfrom a conventional analy.l 1.25 should be regarded as a mini- fators are not used. The results. The section proportions of the framing members at the joint should satisfy the requirements of AC1 ForType 1 a. and shear. significant increase in steel stress above the actual yield perature should be taken into account. Critical 3. (b) the reinforcing bars will strain harden at member dis- The joint should resist all forces that may be transferred placements only slightly larger than the yield rotation. Type 2 is a joint that connects members that are required to dissipate energy through reversals of deformation into the inelastic range.2-Definition (a) Due to Gravity Loads (bl Due to Loteml Loads A joint is defined as that portion of the column within the Fig. For Type 2 joints for which the sum of the critical sections for transfer of member forces to the joint are column flexural capacities exceed the sum of the beamflex- at the joint-member interfaces. C = com- depth of the beam(s). A value of a = 1. 3. which were the effect of any member eccentricity. 2. I(b) representing tension and compressionfrom the beams sections for bars anchored in the joint are defined in Section should be based on the area of steel provided and the speci- 4. shrink.2.25 3. using those combinations that pro. or blast effects are of this category. including statically determinate test specimen. Any joint in a typical frame Ccl TCl designed to resist gravity and normal wind loads would fall into this category. In the latter case. Critical sections for shear Ural capacities along any principal plane. forces within the joint are defined in Section 4.1 shows the joint as a free body with forc. V = shear force.r 1.2-At every joint. cause only limited ductility is required in members adjacent sis. joint including axial loads.51. 3. jIed yield stress modiJied by a. 3.2-Forces with due consideration of column axial load. BEAM-COLUMN JOINTS 352R-3 special ductility requirements. monly 10 to 25 percent higher than the nominal value. The joint is identical. very high winds. For Type I joints [represented in Fig. Joints in moment resisting frame structures designed to resist earthquake motions. due to gravity loads. temperature. For reinforcing steels whose proper- 33. 1.2. The primary junction of ties in a tied column is to prevent CHAPTER ANOMINAL STRENGTH the outward buckling of the . Section 4.3 should be pro- Section 3. The through the joint should satisfy Sections 10.2.1.2-Longitudinal column reinforcement passing forcement of the deepest member framing into the joint.75hy 4.1-Transmission of the column axial load through the size to effectively replace the cot@ement provided by ties. should be provided through the total depth of the joint except for locations or in directions as defined in Sec- tion 4. (100 mm) of the column width uncovered on either side of the beams.2.of center-to-center spacing should not exceed 12 in.1.1.3.1-Transverse reinforcement. crete in the column core by a combination of longitudinal 4.be satisfied 3. tween the top and bottom levels of beam longitudinal rein- 4.1 and 10.1. according to Chapter 4. Transverse rein- resist the most critical combination of forces as defined in forcement satisfying Section 4. the center-to-cen- ter spacing between adjacent longitudinal bars should not exceed the larger of either 8 in. AC1 318. Some typical cases are shown in Fig.3 are permitted: (b) ~onmvJ tf j$syE a) Where beams frame into all four sides of the joint and providing c&f inement where each beam width is at least three-quarters of the Fig. to joint into which the beams frame.2-Within the depth of the shallowest member framing into the joint.2.2. Section 4. the center-to-center spacing within the joint. ties may be omitted within the joint ifthere are trans- 4.2. the column width remains uncovered on either side of the beams. ~ J4” Al 4. . (300 mm). 4. 4.2. Further.3 does not need to be satis- Serviceability requirements are intended primarily for fied.3-Transverse reinforcement should satisfy Sec- column reinforcement plus either transverse members fram.9.l-Dejnition of adequate lateral confining members column width and does not leave more than 4 in.2.3 does not need to.~uSJing of the column core. joint region requires adequate lateral confinement of the con. the following exceptions to Section 4.10 of AC1 3 18 as modified in this section. as defined in Sec- -7-T Y tX bY hY tion 4.1. The requirements of this section are in- tended to insure a relatively uniform distribution of the lon- gitudinal bars in Type 2 joints.1.1.2-Transverse reinforcement SC byr0. At least two ing into the column or transverse reinforcement.1.2. (200 mm) or one-third of the column diameter or cross section dimension in the direction the spacing is being considered. members meeting at a joint.2. However. longitudinal column bars may be offset sisting nonseismic lateral loads.1. longitudinal column bars extending Type 1 joints. The provisions of AC1 3 18 for offset bars of the transverse reinforcement should not exceed 6 in. the designer joint and the beam widths are at least three-quarters of should consider the possible ejfect of joint rotations on the column width and no more than 4 in. To facilitate placement of transverse reinforcement in For Type 2 joints. No additional requirements over b) Where beams frame into only two opposite sides of the those given in ACI 318 are specified. mm).2. For Type 1 joints.2. as defined layers of transverse reinforcement should be provided be- in Section 4. (150 should be followed. cap or split ties may be used provided the lap through the joint should not be offset at the joint and the area length is sufficient to develop the tie strength. vided in the direction parallel to those two sides. Research on c01umn~‘~~~~ 2s*29*31 subjected to severe load reversals has shown that a uniform distribution of the col- (0) Plon view of ’ iti with umn longitudinal reinforcement area improves confinement komsinbo xondy BIy g~.4-Strength considerations in the direction perpendicular to the two sides of the All joints should be designed.column longitudinal bars and to REQUIREMENTS provide some confinement to the column core. MANUAL OF CONCRETE PRACTICE of column reinforcement should be distributed around all pe- rimeter faces of the column core. A 1 ” 4. If the beam-column joint is part of the primary system for re- For Type 1 joints.l-Compression verse membersframing into the joint that are of a sulficient 4. tion 7.2.1.1.1-Type 1 joints 4. (300 mm).2.9. or both. (100 mm) of cracking and defection. In no case should the spac- ing exceed 12 in. (4. (150 mm). However.2.2. third of the minimum column dimension or 8 in.2) required to maintain the stiffness of the sides of the grid- Jyh work.09 . the total cross-sectional area in each direction of a sin.2. When ties are recommended in a joint which is part of the In the design of building systems resisting earthquake primary system for resisting nonseismic lateral loads. Thus. The limitations on size and spacing of transverse rein- gle hoop. The provided confine. center. (4.2.2. ground motion (not the reduced seismic design lateral forc- 4. The coefficient 0.09 in less than 135 deg at their ends and 6 bar-diameter extensions.3) Jyh not be less than half that required in Sections 4.2. should be arranged such that the 135 deg bend is at the exte- forcement (hoops or hoops and crossties) sh should not ex. quate conf%tement to the joint during anticipated earthquake Recent research result$8*32*33~46*48*56~62 have shown that loading and displacement demands.4 should be provided to minimize joint deterioration.1) without a loss of vertical load strength.2.’ Section 4.2. Single leg crossties should have a 135 deg bend with a 6 bar- havior of tied columnP*29*31 which have properly detailed diameter extension on one end and the other end may have a hoops and crossties. Crossties are A.1) (4. BEAM-COLUMN JOINTS 352R-5 When required. ceed the least of one-quarter of the minimum column Recommended shapes of closed hoops and single leg dimension. tailing of the members and joints which comprise the the volumetric ratio P. or 6 in.2(a).2-Type 2 joints el of earthquake excitation is provided for by the special de- 4. 4. runs along the outside edge of the confined column core.. rior face of the joint.’ ble of adequately confining the column core. quired.2.2. a shorter extension is permitted for the 90 deg bend 4.1.2. in which case the reinforcement should A. Members which are not included in this system should also be capable of undergoing the same deformations as the primary system (4.1-When spiral transverse reinforcement is used. when re.2. where the loss of cover could affect the anchorage of .2.1 of AC1 318. The lateral center-to-center spacing between standard 90 deg tie hook is permitted.. six times the diameter of longitudinal column crossties are shown in Fig..2 for spacing of longitudinal bars in Type 2 joints.2.2.6-All hoops should be closed with hooks of not those given in Chapter 21 of ACI 318. (300 mm) and each end of a crosstie should en.2. es) or else the nominal hooping recommended in Section verse reinforcement as defined in Chapter 2 1 of AC1 3 18 is 4. transfers within the joint. are intended to create a steel gridwork capa- s.2.2.3 and 4.2. Spacing limitations of Sections 4.2.5-Transverse reinforcement. If 4. = 0. joints. f .AIf a joint connects members which are not part because increasing the extension would offer only a slight of the primary system for resisting seismic lateral loads.h”f.1 and 4. the 90 deg ends should be alternated on opposite faces of the primary system for resisting seismic lateral loads.2. shall be provided at each layer of transverse rein.2.2. should be provided unless the joint is confined on all sides by structural members which satisfy s.2. as defined in Sec- but should not be less than tions 4. but does not provide crossties or legs of overlapping hoops should not be more effective anchorage because the extension beyond the bend than 12 in. but improvement. the vertical center-to-center spacing between layers of trans- ments of ACI 318 for tied columns plus additional recom.LLFor joints connecting members which are part used. as defined in Section 7. installation of such crossties usually is dift?cult. Eq. standard tie hook. members which are not part of the primary system should be either flexible enough to respond elastically to the anticipated but should not be less than that required by AC1 3 18. = 0. should not exceed the smaller of one- mendations which confSte the column bars through the joint.2.4 The speci$ed reinforcement is expected to provide ade. the of the column. single leg crosstie would have a 135 deg bend at both ends. it is assumed that loads have been reduced to a level recommended spacing is limited to 6 in. However.2. in the case of exterior and comer with the primary system for resisting seismic lateral loads. The preferred shape for a bars to be restrained. . Crossties.2. the forces.2-Where rectangular hoop and crosstie trans.2. to provide additional confinement to the joint. overlapping hoops. verse reinforcement s.h”f.1) and (4.1 and 4. 4. center to wherein member forces are determined by elastic theory.~ should be primary system for resisting seismic lateral loads. (4. In exterior and comer joints. (150 mm). or hoops with crossties of the forcement given in this section. when combined with the lim- same size should be at least equal to itations of Section 4. the crossties center-to-center spacing between layers of transverse rein. gage a peripheral longitudinal reinforcing bar.2. bend is used it should be alternated on opposite faces along mation in the inelastic range for deflection compatibility the column. (200 mm).. Eq. ties in the joint should satisfy the require.3) was selected based on the observed improved be.3? (A/A. smallerpercentages of transverse reinforcement can be used ment is also expected to be sufficient for necessary force when adequately sized transverse members are present. Thus it is recommended that when a 90 deg the members must be designed to sustain reversals of defor. apply regardless of confinement conditions.2) are the same as 4.2.1.2. used. A forcement. The inelastic response that is expected at the anticipated lev- 4. Further. or greater than beam (b) Single Leg Cross Tie width bb plus half the column depth h on each side of the Fig. An exterior joint has at least two horizontal members framing into opposite sides of the joint. (4. 4.2.5) where b.4) where + = 0..1-For joints with beams framing in from two perpen.3-Shear for Type 1 and Type 2 joints sified as an exterior joint for Table 1. The constant y for Eq. The committee has reservations about umn and the total depth of the most shallow horizontal mem- the adequacy of the specified extensions. compressive strength f. height than the minimum distances specified.4.2. the joint should be extended into the columns above and be.3~An interior joint has horizontal members framing Minimum distances for extending the joint transverse re.4 of AC1 3 18. to be clas- 4.7-Transverse reinforcement layers required in pends on the joint classification. then the 7 value for sion and compression forces in the members framing into the this joint should be selected from Column (c) of Table 1. joint as specified in Section 3.6) but not greater than column width b. the nominal shear strength of the joint (0) Closed Hoop is V” = ‘YE (psi) bj h vn = 0. zontal frame members on the two opposite faces of the joint dicular directions. should be computed on a horizontal plane at the less than three-quarters of the total depth of the deepest midheight of the joint by considering the shear forces on the member framing into the joint. is the effective joint width and h is the thickness of the column in the direction of load being considered. of the deepest horizontal member framing into the joint. umn (b) of Table 1. The following equation All other joints should be classified as comer joints when should be satisfied selecting a value for yin Table 1.3. . as defined in Chapter 2. bb should cross ties at the 90 deg be& it is recommended that only 135 be taken as the average of the two widths. the horizontal shear in the joint should be should cover at least three-quarters of the width of the col- checked independently in each direction. However. If the two horizontal frame boundaries of the free body of the joint and the normal ten. (4. should also be provided in the beams adjacent to the column..2. In such cases then the y value for this joint should be selected from Col- the joint transverse reinforcement should be extended to cov. members do not satisfy this requirement.26 such as at the top ber should not be less than three-quarters of the total depth story or at the base of a first story column.5) should not be larger than verse reinforcement as required by Chapter 21 of ACI 318 6000 psi (42 MPa). to be classified as an inforcement into the columns to provide confinement to the interior joint for Table 1. as defined in Section 4. The design shear umn and the total depth of these two members should be not force V.2.4.’ in Eq. where the poten. the horizontal frame members column core above and below a joint are given in Section should cover at least three-quarters of the width of the col- 21. 4. deg bend be used at the exterior face of the joint. er the entire potential flexural hinging zone. the widths of the hori- 4.85 and V. and joint type. The effective joint width bj should be taken as U+.2-Requited dimensions of beam.083~8 (MPa) bj h (4. Trans. The term b* is the width of the beam in the ditection tmnsverse reinforcement of loading. The value for the low the joint as required by Chapter 21 of AC1 318.252R-6 MANUAL OF CONCRETE PRACTICE Table l-Values of y for beam-to-column joints Joint classificaton Joint type ( a ) I n t e r i o r 1 (b) E x t e r i o r 1 ( c ) C a n e r 1 24 20 I5 2 20 I 15 12 b (4. into all four sides of the joint.3. If tial flexural hinging zone may extend further into the story the four horizontal members do not satisfy this requirement.5) is given in Table 1 and de- 4.2. Where beams of different width frame into oppo- site sides of the column in the direction of loading. However. + bc) bj= 2 (4. . but such eccentrici.4-Evaluation of horizontal joint shear er also vertical shear forces in the joint. 4.4.AFlexure 4. Similarly.2 will provide adequate vertical reinforcement in the joint to carry that component of joint shear.1 and 4. 2) Exterior ing the joint shear capacity in both directions. 4. 4.” The designer should consider the possible conse- quences of member eccentricities on jointperformance when designing and detailing the joint. there is insufficient research on eccentric . If the dimensions of the horizontal mem- bers do not satisfy the given requirements. 4. To provide this con- finement. Sections 4. and that value is used when check- (b.connections to de- velop specific design recommendations.3-Geometric description of joints the column centroid. t 1 Corner (c. only one classification is made for a joint. 4. only one value for y is selected from Table I for the joint. Fig. then a lower value of y is specified. then a lower val- + ue of y ir specified. . (4.2 contain recommended details A22 for column longitudinal and transverse reinforcement in the I t joint region. and cor- ner joints are given in Fig. h=%lfCbL-% ties have resulted in apparent increased earthquake damage.5-Determination of effective joint width b.1-Flexural design of members at the joint should be Plan Views based on the provisions of AC1 3 18. The procedure for determining the joint width in + I- cases when the beam width is less than the column width is (c.3. It is expected that the recommendations for the distribution of the column lon- gitudinal reinforcement given in Section 4. 4. Column Not all joints which have horizontal membersframing into ams all four sides of the joint can be classified as interior joints when using Table I.1. 4. Again.! I Exterior (b. not all joints which have horizontal members framing into two opposite sides of the (a 1 Interior joint can be classified as exterior joints when using Table 1. That is. The design philosophy embodied in Eq. Committee 352 has also addressed the construction problems resulting frDm congestion of rein- forcement in beam-column joints. BEAM-COLUMN JOINTS 352R-7 The geometric descriptions of interior. Joint Elevation Beom Section Some researchers2°. The shear provisions adopted by Committee 352 are in- tended for limited displacement and rotation levels and also anticipate the beneficial effects of load redistribution in a re- dundantframe structure. exterior.2) Corner shown in Fig. Although the joint may be designed to resist shear in two perpendicular horizontal directions. if the dimensions of the horizontal members do not satisfy the given requirements.38 The normal procedure for calculating the horizontal de- Beams sign shear in an interior and an exterior joint is shown in Fig. (4.4. The concrete compressive strength in Eq.43 have pointed out the need to consid- Fig.5) is limited to 6OOOpsi (42 MPa) because only limited research data are available on the behavior of connections constructed using Column Column Beam higher strength concrete. At the present time. torsion may occur.5.5) is that during anticipated earthquake loading and displacement demands. the joint can carry the specified shearforces if the concrete within the joint is adequately confined. In cases where the beam centerline does not pass through Fig. then l. (4. tended to produceflexural hinging in the beams rather than b) For No. Thus.~.. In certain cases.352R-5 MANUAL OF CONCRETE PRACTICE 4X-Development of reinforcement 4. 4.2.7). 11 and smaller bars. During intense seismic loading.5. the development length l& of than 1. the sum of the nomi. are provided along the full development length at a Therefore. both above and a) For No. should be located as far from the critical section as possible.42-44.1 Bar sizes should not exceed No. frames should be computed as follows are designed with deep long-span beams and relatively small columns. all terminating bars should For portions of the structure which are not part of the pri.2. If this provision is not met. the 1. should be included in calculating the beam moment c) Where reinforcement in the flexural member is pro- strengths..2. However.4 factor is a minimum value and a higher spacing not greater than 3d. f. rC. should not be less 4. (4. (4. where db is the diameter value could be necessary to develop beam hinging in struc. on the effective width of slab to use in determining the beam flexural strength.7). lclhr as given in Eq.4.3. ldA. Research results” have shown that the concrete cover over the column bars quickly becomes inef- fective for bar development in Type 2 joints.6).2K(MPa) joint and should extend a distance at least equal to twice the effective depth of the column cross section. The development length. The minimum development length I. of the hooked bar.5. if side cover normal to the below the joint boundaries.3-For Type 2 joints.3-For Type 2 joints which are not part of the primary ‘dh = SOR(psi) system resisting seismic lateral loads.4. (150 below the joint. the criti- Fig. multiplied by 0. The committee continues to review given in Eq. and anchorage for fy is not specifically required.. tem for resisting seismic lateral loads. mea- due to a severe earthquake is not critical as long .. Recent studiesf 7.2 For Type 1 joints. column hingmg using a 90 deg standard hook. should not be less than 8db or 6 in. 75 fi(psi) .&Critical section for development of beam rein...0.2. transverse reinforcement is used. (50 mm).8. may tures with heavily reinforced slabs. moment reversals are to be expected at beam-to-column joints which cause stress re- versals in the beam and column longitudinal reinforcement at the connection.63 hve shown vided in excess of that required for flexural strength the presence of a slab to have a significant e@ect on the per. may be reduced by the ratio this data. the minimum column-moment strength. Appropriate slab width be multiplied by 0. calculated using the axial load which gives mm>. (65 mm) and The requirement that the sum of the nominal moment cover on the bar extension beyond the hook is not less strengths of the column sections above and below a Type 2 than 2 in. if the hook is enclosed ver- in the columns.(required)/A.2.2-For Type 2 joints which are part of the primary sys. this ratio should be checked independently in each direction. be hooked within the transverse reinforcement of the joint mary system resisting seismic lateral loads.5.(provided). the ratio of column to beam moment strengths should be greater than 1. 4.7.5. 11 and smaller bars. cal section for development is taken at the face of the forcement terminating in the joint confined column core (see Fig.8. 11 and hooks 4. plane of the hook is not less than 2V2 in. 1 dh = (4.2 Hooked bars terminating in the joint 4. at this time there is no clear consensus A.1 Critical sections for development of beam reinforce- ment-The critical section for development of reinforce- ment should be taken at the face of the column for Type 1 joints and at the outside edge of the column core for Type 2 joints. as defined in the fol- nal moment strengths of the column sections above and lowing sections.48.7) Section 4.60.5 should be used both above and below the 4. For joints with beams framing follows in from two perpendicular directions. It is recommended that such frames not be part of ‘dh = I the primary system resisting seismic lateral loads.Wd. as given in Eq. as formance of connections. may be joint be 40 percent greater than the nominal moment strengths of the beam sections framing into the joint is in. 4. transverse reinforcement as specified in fyNWd. as is normally preferred in the seismic design tically or horizontally within ties or stirrupties which of moment resisting reinforced concrete frame structures. 4.5.Y-S~S8.62..as proper sured from the critical section as defined in Section 4.4 times the sum of the nominal moment strengths of a bar terminating in a standard hook should be computed as the beam sections at the joint.5.1. 4 to avoid congestion problems.5.5. which were derivedfrom work For Type 2 joints.’ = specified compressive strength of concrete in the exceeds 12 in(300 mm). (4. within the confined core so the 0.5. and usually through.1.5. l = fYWAt. The purpose of the recommended value for h/d. A thorough treatment connection should be taken as of this topic is found in Reference 38.5. this slippage should be 4.+ may & = specified yield strength of spiral reinforcement be reduced by the ratio A. 4.4 large. shear cent.5.-----j I 4.4 Beam and column bars passing through the joint- height of the connection.5. Slip of reinforcing bars is not usually accounted for reinforcement will be greater than specified in Section in normal design. 4.3.7-Bond stress on straight bar passing through the joint terminating at a connection will be anchored using a stan- dard hook as defined by ACI 318. (4.5-For multiple layers of reinforcement.8.5. To reduce the bond stresses to a value low 4. as given in Eq. 12. In most cases.h = specified yield strength of hoop and crosstie rein- vided in excess of that required for flexural strength forcement and anchorage for fY is not specifically required.1-Straight bars should be No. However.2(a). limit slippage of the beam and column bars through the con- verse reinforcement. = area of column core measured from outside edge to (4. = design width of beam Eq.3-Straight bars terminating in Type 1 joints considered.. all straight beam and column bars pass- done by A CI Committee 408. Sections 12. beam and column bars may slip within the beam-column tored into the equation to reflect the detrimental effects of joint during a series of large moment reversals. The differences between Eq. 11 or smaller and enough to prevent bar slippage under large load reversals the development length for a straight bar terminating in the would require very large connections.. Section 4. As shown in load reversals.(column bars) 2 20 several factors including: (I) the hook in a Type 2 joint must be enclosed.3. ture for inelastic dynamic analysis.5. 4. afr (MPW. = gross area of column section but not less than Ash = total cross-sectional area of all legs of hoop rein- forcement.( in. = area of individual bar A.O58d. the bars in each layer must satisfy the given criteria.(mm)&(MPa)] b.8) reflect h(beam)/d. db = nominal diameter of bar a) If the depth of concrete cast in one lift beneath the bar f.2. l.22.2.5.3.2.5. = width of column transverse to the direction of shear the column. the mid- 4. is to reflects the beneficial effects of very closely spaced trans.7) and (4.9) outside edge of either spiral or hoop reinforcements A. the spacing of transverse nection.AIf transverse joint reinforcement is provided at a spacing less than or equal to three times the diameter of the bar being developed l.2. (4. Sections 4.2.5.4 of AC1 318. (2) an increase in length is fac.8).5. ing through the joint should be selected such that Eq. (b). The required development length is For Type 1 joints.2(a) is included.8). (4. may be multi- plied by 0. For most Type 1 and all Type 2 exterior connections. . the bond stresses on these straight bars may be very deformations is included with the fator 01. crossing a section having a core dimension h” OLMBkfd.3.7 factor of Sec.. when modeling a frame struc- 4.7) and (4. Any portion of the straight embedment length b) = effective width of joint transverse to the direction of not within the confined core should be increased by 30 per. = specified yield strength of reinforcement b) Where reinforcement in the flexural member is pro.7.3.2 and 12.2.5.7) is a combination of the provision in ACZ 318.3. and(c) h(column)/d&ieam bars) 2 20 are identical to Section 12. (4. and 12. h = full deoth of column or full deuth of beam .*) d CHAPTER r--NOTATION 25 &(psi) A.2fl(MPa) h (co1 1 . The tail extension of the hooks should project toward.8) ‘dh = 6. no recommendations are made.” and (3) the increase in stress under large Fig. I. bars Fig.(provided).(psi) [O.(required)/A.. (4.2.9) assumes the bar is contained within the core of b. should be increased by 30 joint percent. Various researchers14~19~3~33*~~s1@ have shown that straight tion 4. given by Eq. including crossties. pp. 1971. Place Beam-Column Joints. ACI-ASCE Committee 352.” No. J. N. forced Concrete Column Sections in Seismic DesTgn. S. “Failing Behaviors of Re. A... 79. “The Elastic Be- terior Beam-Column Joint Under Seismic Loading.” Publication No. M. M. 1967... Park.353 pp. crete Beam-Column Assemblies under Simulated Seismic ume of core (out-to-out of spirals) Loading. Aug. and Connor. Christchurch. SRS 403. J. V. Nov. 533-560. V... 585- 7. 5. “Behavior of Rein- ld = development length for a straight bar forced Concrete Beam-Column Joints Subjected to Slow ldh = development length for a hooked bar. Wight.. “Reinforced Beam-Column Joints under Cyclic Loading.. Urbana-Champaign. 19. Oct. Department of Civil 1979. and Hanson. and Sozen.. New Zealand Ministry of 4 = strength reduction factor Works and Development. University of Canterbury. Sept.” Report No. 6. and Priestly. 1978. De- sh = center-to-center spacing of hoops or hoops plus partment of Civil Engineering. University of California. Y . Christchurch. 74-9. rures in Seismic Zones.. and Jirsa. V. “Seismic crete Beam-Column Joints for Seismic Loading. T. 9. Seattle. “Ductility JOURNAL. of Reinforced Concrete Beam-Column Joints. 11. 1977. Hanson. and Park R. 17. Tokyo Metropolitan University. S..” AC1 21. 1978. R. of Rectangular Reinforced Concrete Columns With Axial 8. Park. No. . ceedings. 129-144. “Testing of Two Reinforced Con- PS = ratio of volume of spiral reinforcement to total vol. Higashi. 73. Department of Civil Engineering. ert D. M. 78-13.” Proceedings. Proceedings V. Joints. 75.. P. S.114 pp. Norman W. American Concrete Institute. Harold W.84 pp. T. “Reinforced Con- 1. Mar.. 293. M. Cited references 15. J. and Ohwada. “Seismic Resistance of Concrete Loads. Paulay. C. forcement area A. 1968. outside to outside Engineering. pp.350. Uzumeri. pp. R. “Ductility of Rein. Structures and Mechanics Report No. 1977. 91.” ME thesis. 103. Norman W. C.” AC1 JOURNAL. 13.‘* Report Resistance of Reinforced Concrete Beam-Column Joints. “Recommendations for CHAPTER 6-REFERENCE!3 Design of Beam-Column Joints in Monolithic Reinforced Concrete Structures.h t. Detroit. by lateral members 12. R. Priestly. Nov... “Building Code Requirements for 14. and Park. K. “Behavior of Pre- WI = nominal moment capacity of section stressed. Duane L. A. 74-05.” Reinforced Concrete Srruc- kodate College by the Tokachioki Earthquake..W. University of Canterbury. and Fourney. Hawkins.” Repot7 No. University of Texas at Austin. E. “Strength and Ductility of Cast-In- 3. 1975. perpendicular to the transverse rein. Rob- 2. Department of Civil En- in Reinforced Concrete Columns Subjected to Large Deflec.. ASCE V. July 1976. ‘The Shear Strength Reinforced Concrete (AC1 3 18-89). Structures Research Laboratory. Vii = nominal shear strength of joint 11. Paulay. Park. Referenced standard 7. Proceedings.” Research Report No. K. Partially Prestressed..290 pp. Y. Richard A. R... University of Toronto. neering Research Center. V.. Feb.” New havior of Earthquake Resistant R. No. Earthquake Engi- Frames with Grade 60 Reinforcement. 0. 1977. Park.” Report No. 11.. 1975. Fenwick.* being designed 9.. Gill. H. G. M. University of Illinois.. 97. M. edge of bar. T. Concrete Beam-Column Joints Under Seismic bActions.42 pp. Lateral Loads.” Pro. “On the Damage to the Ha.. N. ~ AC1 JOURNAL. 142. University of Washington.101. 1977. 26.-Japan Seminar of Earthquake Engineering Detroit. D. U. ‘RC Beam-Column Joints under Large Load Rever- inforced Concrete Beam-Column Connections Subjected to sals. M. VU = design shear force in joint E. Dee... R. University of Auckland. pp. D. 593.. and Priestly. pp. 19. Renton. Sendai. Wellington. “Revetsed Cyclic Loading Bond Deterioration Tests. 1972. pp. 16.1. N. pp. hook 10.” Report No. 1685-1700. Feb. J. Department of Civil Engineering. 1989.” Memoirs No.. No.. gineering. M. Department member interface of Civil Engineering. and Sampson. Bertero. 18. pp. Wight. 136 pp. Mar. Jan. and Se&in M. = core dimension of tied column. Vallenas. F. and Reinforced Concrete In- 4’ = increased moment capacity of section when using a terior Beam-Column Assemblies under Cyclic Loading: > 1.” Report No. ‘The Behavior of Reinforced Concrete 20. J. Ohno..” American Concrete In. June 1971. SM 75-5. STJ. crete Confined by Rectangular Hoops Subjected to Axial 4. No. 15. UCB/EERC-77/13. 1%9. crossties Christchurch. 1970. “Shear Strength Decay Load. and Shibata. 543-55 1. Kobayashi. Lee. SP-53.” University of Canterbury. AC1 Committee 318. Aug. “Con- Sept. Proceedings V. Uzumeri... ST12. Interior Beam-Column Zeulund Engineering (Wellington).. Faculty of Technology. Y = shear strength factor reflecting confinement of joint Nov. R. and Thompson. 77. J. pp.. 1977. 1973. with Emphasis on the Safety of School Buildings. ASCE. Megget.. R. Hanson. tion Reversals. and Popov. G. 341-353.. Berkeley. 69. 1972. stitute. 93. 1974.1. Meinheit.. N... M. 375-393.S.0 Test Results of Units 1 to 7. Department of from the critical section to the outside end of the Civil Engineering. Briss. 5-7511. 1974. pp..” Proceedings. W. measured Load Reversals.” a = stress multiplier for flexural reinforcement at joint. L. V. Proceedings V. K. M.. J. ST6. University of Canterbury.” Research Report No. “Reinforced Concrete Ex. 2337-2350. N. Christchurch. ASCE. and Irvine. James K. Aoyama. 23.. “Effect of Joint ings. “Seismic Behavior of Lightweight Concrete Col. 13-27. 106 pp. Part 1:1982). 1982.. July 30-Aug. Monterey. Bullefin d’lnfortnution No. Murry.. “Overview of the Japanese Building Code 24. the Building. Robert. R. Feb.. 6. neering. Wellington. “Seismic Requirements for Reinforced Concrete Beam-Column Joints Behavior of Lightweight Concrete Beam-Column Subas. and Jirsa. Christchurch. V. 82. T. 82. T. J. K. Aoyama. Reinforced Concrete Beam to Column Connections Subject. Bond Deterioration in Reinforced Concrete Beam-Column sium on Structural Concrete Under Seismic Actions (Rome. ACI-ASCE Committee 352. SP-84. 929-950. 53-60. O. 1979. March-April 1985. Meinheit. 1984. 2. Scott. “Experimental Ana. 1. 38. 106. “Behavior of Exterior crete Institute. 46. Popov. California. Texas. N. and Priestly. James 0. Durrani.. “Stress... No. pp. 36. No. J. Jan. 5. M.~~. “Code of Practice for the Design of Concrete Struc. and Park.” Report No.. ST5. 188. pp.. “Effect of a Slab on jected to Reversed Cyclic Loadings. San Francisco.” Research Re.” Journal of Zealand. 445-452. May 1980. Paris. V. pp. Shear Reinforcement on Behaviors of Exterior Beam-Col- 27.” (NZS 3101. University of Mich. D. July 1986.. search.” PMF. University of Canterbury. 25. S. H. V.” Re- 82R3. No. Liande. “‘Earthquake Load (NZS 3101. J. and Jirsa..” Earthquake Ef- Department of Civil Engineering. “A Study of Shear Be.. J.” Transaction of the Japan 26.. H. 30. ST& Aug. J.” Truns- Tension. and Design Examples. U.” AC1 JOURNAL. 1079-1102. 3. 80-6.. R. ternational du Deton. 8th World Conference on Earthquake Engi- 1982.. “Problems Associated with ‘Weak- of Canterbury.” PCA Construction Technology Laboratory/National Beam-to-Column Connections. 1982.. “Suggested Development. G. K. fects on Reinforced Concrete Structures. .) 49. J.. 1984. Park. “The Effect of Floor Member Size on the havior of Reinforced Concrete Beam-Column Joints. Hoops at Low and High Strain Rates. S.” Journul of 28. pp.. H. Martin. pp. Science Foundation. gineering. M. port No. University of Michigan.. Beam and Slab on the Behavior of Reinforced Concrete umns.” Re- Strain Behavior of Concrete Confined by Overlapping search Report 84-9. Wayne D. James O. Daniel. (Avail. ASCE..-Ja- semblages. 316. and Priestly. 1979. 31... B. Kanada.. Zhang. AC1 Committee 408. Ehsani. M.” Proceedings. 1982. Selna. 77. M. and Jirsa.. and Kurose. port No. University 42. S. Comite Euro-In. Sheikh. J. 266-283. pp. ASCE. Y. American Concrete Institute. J. 34. Joints. and Wight. Zerbe. pp.1R-79). July 1982. and Wight. S. and Durrani. Nigel. UMEE 82R5. R.. K. 1980. 38. R. “Re- and Ductility of Tied Concrete Columns. and Morita. V. “Joints in Reinforced Con- 29.. and Standard Hook Provisions for Deformed Bars in Width of Slabs in Reinforced Concrete Structures. and Uzumeri. B. M.. B. and Aoyama. ST1 1. I.-N.. Washington. “Properties of Con. L. 127 pp. J. 433440. Sosngchao. 559-566. V. V.. Ann Arbor. 83. 163-201. Jan-Feb. Kondo. R. Structures. 1984. Ehsani. and Gill. 30. and Wyllie. 33. pp. Proceedings V. No.” Transaction Strain Relationships for Confined Concrete. BEAM-COLUMN JOINTS 352i?-11 22. University of Texas at Austin. umn Joints under Reversed Cyclic Loadings. Column Joints.. pp. I. B. “Commentary on The Design of Concrete Structures. 1985. 44. Paulay. Joglekar. 43... 1982. Department of Civil Engineering. 1980. pan Seminar on the Design of Reinforced Concrete Beam- Feb. able as PB83-204 891 from NTIS. M. 37. Priestly.. No. 1985. and Tough Concrete Columns for Seismic Forces. Department of Civil Engineering. American Con- 32. “Full Scale Tests of Beam-Column Joints. New Zealand. Apr. 7. ASCE. July 1983.1. 1983. ASCE.... action of the Japan Concrete Institute. D. W. A.. 1. lation Between Beam Bar Anchorage and Shear Resistance ASCE. pp. M. N. A. Scott.3 pp.. Yoshimura. NO. S. V. V. 1982. sity. 156 pp.” PMFSEL Report No. S. March 1985. Nov. 79. 1..” Report No. 1982. 1985. G. M..S. A.” AC1 JOURNAL. Christchurch. Wellington. T.. Standards Association of New on R/C Beams: Building Versus Single Beam. J.” SEL Report No. Sattary-Javid.” Proceedings. R. “Stress. ST4. Standards Association of Concrete Structures. V.... 41. K.. of the Japan Concrete Institute. 112. E. J. M.. Beam’ Design of Reinforced Concrete Frames. 271-304.. Park. N. 44-52. and Wight. Apr. V. Department of Civil En- May 1979). pp. and Klingner. pp. 45.C. Houston. Fujii. K. D. 132. UMEE the Behavior of Exterior Beam to Column Connections. University of Texas at Austin. Weinmaun. S.” AICAP-CEB Sympo. July 1984. pp.” Paper prepared for the U. Fujii... Kanada. Rice Univer- igan.” AC1 JOURNAL. R. and Wight. 106. Pro. Park.” 50. Proceedings. Department of Civil Engineering. Rabbat. She&h. K. Suzuki. and Forzani. V. “Strength 40. 7. J. S.-Japan Research. U. and Han. V.-Japan Re- AM Arbor. L. and Uzumeri.S. Jirsa.Z. 2. pp. Strength of R/C Beam-Column Connections. pp.243 pp. 2227-2244. 48. “Strong Concrete Institute. 1982. 108.. L. ed to Earthquake Type Loading.. 39.” Pro. Leon. “A Study of crete Confined by Rectangular Ties. (AC1 408. “Effect of Transverse son. P. H.” Earthquake Effects on Reinforced Concrete ceedings. Detroit.S. Donald F. crete Frames Designed for Earthquake Resistance. “Inelastic Behavior of “Ductility of Square-Confined Concrete Columns.. pp. 309- Detroit. and Morita. The University of Tokyo (B). at Exterior Beam-Column Joints. 1985. Part 2:1982).. “Shear the Faculty of Engineering.” AC1 JOURNAL. 1980..195. Design of Beam-Column Joints in Monolithic Reinforced tures. “Recommendations for 35. Structurull Engineering. Detroit 1985.. Zhu. E. 1717-1734. P. June ceedings V. Department of Civil Engineering. Bertero. 47. lytical Study of Internal Beam to Column Connections Sub. Behavior of Reinforced Concrete Beam-Column Joints. Shamim A. 75-105.” Proceed. SP-84.” American Concrete Institute. Park. V.275 pp. Sept. Otani. 107. 82-1. May-June New Zealand. M. V. R. “The Effective Splice. This allows all of the beam longitudinal 56. nections where beams are wider than columns and beam lon- Oct. 1298-1308. K. mic Response of RC Buildings Loaded to Failure. and Vallenilla. than the beam width. No. and Zerbe. Abdel-Fattah. Sept.C. No.” AC1 JOURNAL.. A. J.. Sept. ASCE. Concrete Frame Subassemblages . pp. pp. Sept. H.” joint. V. W. frame into columns such that the outside faces of beams and bution in Earthquake Resistant Design of Ductile Reinforced columns are flush. Kitayama. 1988. w effects of floor slabs. Jan. It is not clear to what extent the presence Concrete Frames. Yokohama 227. 581-588. and Wight. No. 1986.. pp. Limited resultsS2 are available for the capacity of joints 63. No.S. 84. A. S. B. Nanjing Institute of Technology. V... “Behavior of of the items listed is arbitrary. V. 16. 1092-l 108. for small columns the loss of section due to comer spalling “Elastic and Plastic Behavior of Reinforced Concrete Beam combined with the loss of bond and slip of the highest in Consideration of Axial Restriction Effect of Deforma. Aktan. opinion of the committee members and designers. 9.-Feb.” Paper Prepared for the U.. 1987. No. and Sakata.Z..*’ ACI Structural Journal. ASCE. different beam geometries.. 13.. ASCE. Otani. This research indicates that 61.” Transaction of the Japan Concrete Insti. ASCE. 5. Durrani. The order 55. Aug. column axis are also common. Leon. S. and Durrani. and Aoyama. A. V. R/C Floor Slab in Resisting Lateral Loads. biaxial loading on joint behavior.. C. needed research topics. V. S. gatsuta.. longitudinal reinforcement. 1989. “R/C Beam.J.. 1987.” Journal ofStructural Engineering. University of Canterbury. E. New Zealand. “Evaluation of Seis. 9. S.” Canadian Journal of Civil Engineering. the com- Japan-China Seminar on the Design of R.12 MANUAL OF CONCRETE PRACTICE 14. H. Jan. Bond Requirements for Interior Beam-Column Connec. H. 115. V.” A&-Biaxially loaded joints Journal of Structural Engineering.-N. Kokusho.. Hayashi. 1987. 64. the capacity of these connections. No... No. 84. Nov. and French.. Otani. 65. 1. and Shahrooz.“Seismic Response of Reinforced 53. H. AZ-Effect of eccentric beams pp. J. 84. 5. R. H. pp. E. K. Moehle.. “Seismic Response of 52. 1507-1523. and Aoyama. 5 1.E.” Report of the Research Laboratory of Engineering is needed to clarify biaxial joint behavior. AJ-Connections with beams wider than columns inar on the Design of R. 2261-2275. Christchurch. V. “Behavior of Exterior Rein.. The following list is based on the Christchurch. Li. Ammerman. K. K. 627-649. “Simple Analytical Model for T-Beam in Flexure. Wada.352~. Guidelines are needed for proper detailing to move . of connections where the column width is equal to or greater New Zealand. pp. of torsion and the increase of associated stresses will affect tute. P. and Wight. V. ASCE.” ACI Structural Journal.” Paper Prepared for the U. E.. “Seismic Resistance beams where the axes of the cohunn and beams are coinci- of R/C Exterior Connections with Floor Slab. S. 113. J. V. 2829-2844. M. A. 115.. V.. reference to larger column sizes.A Canadian Perspec- “Comparison of Inelastic Behavior of Reinforced Grdinary.. Beam-Column Joints for Earth.. A. All connections tested to date have included concentric 58. 0. 400-406. Tokyo Institute of Technology. 1. “Beam Bar June 1989. R. Moussa. 1850-1864. S. “Study of Moving Connections in Two-Bay R/C Frame Subassemblies. J. ASCE. et al. 113. J. Durrani. Na.. 3 l-39.. V. Aug. reinforcement to be located within the column longitudinal tance of Reinforced Concrete Interior Connections Including reinforcement.. Japan..-Japan-China Sem. H. S. Aug. tive. APPENDIX A-AREAS NJIEDING RESEARCH forced Concrete Beam-Column-Slab Subassemblages under Bi-Directional Loading. 5. 66. May 1987.. pp. C. V. 1987. China. particularly with Materials... Kitayama. S. S... V. No. A. 60.” Journal of dent.13-1508. pp.. French. pp... March-April 1987. ‘%ontribution of both beam and column bars. damental Theory of Reinforced and Prestressed Concrete. nal of Structural Engineering. 115. quently used in exterior frames of buildings where beams 59. “‘Moment-Red&i. Ehsani. Beam-Column mittee contacted some 60 design firms asking their views on Joints for Earthquake Resistance. pp. Length. gitudinal reinforcement cannot be placed within column 57. C. Research tion. W.T. and Morita. Reinforced Concrete Beam-Column Connections with Slabs.Z.. The current recommendations are based on results of tests quake Resistance. Information is needed on the behavior of con- a Floor Slab. This type of connection is fre- pp... and Aoyama. pp. ‘Earthquake Resis. Pantazopoulou. No. 1989. M. ASCE.” Jdumal of Structural Engineering. Only limited research44*46J3 is available on the effects of July 1988. 11. Otani. Zerbe. R. Pat&e. 114. P. 115. and High-Strength Concrete Frames. where the hinging region has been moved away from the Column-Slab Subassemblages Subjected to Lateral Loads. V. and Bertero.S. V. 1987. 2. 8. Journal of Structural Engineering. No. No. Connections in which beam axes are eccentric to the Structural Engineering. 198’7. 54. 253-270. University of Canterbury.” Journal of Structural Engineering.&Relocation of plastic hinges away from the joint 1-18. B. strained bars can lead to premature column failure. 7. “Interior Joints with Variable Anchorage tions. sign of R/C Buildings. J. No. To help identify areas where research is needed.” Proceedings of the International Symposium on Fun. pp. and Boroojerdi.-N. 6. 1989. 161-169. A. 1989. A. Fujii.C.” Jour- Beam Plastic Hinging Zones for Earthquake-Resistant De. and different anchorage lengths for 62. 37.47. Guidelines are needed to identify “Type 2” joints AS-Fiber reinforcement in the joint within a structure without having to do a comprehensive in- Using fiber reinforcement may be an effective way to re. A. Current limitations on allowable joint shear stresses are More experimental studies are needed to determine if these based on tests of normal weight and typical strength con. crete.7-Knee joints The majority of beam-column joint studies reported are Four design examples are presented. Knee joints. to those used in the first committee report. the joints are part of the primary structural system for resist- minate at that point and usually are anchored in the joint. Ol”X26” connections has been investigated in a number of recent with 4 No.000 psi (130 MPa).13-Limit on joint shear joint. size of members. I3 A short discus- sion of how the changes in the committees recommendations A. wind loads for Type 1 joints and perimental data are particularly needed for cyclically loaded earthquake loads for Type 2 joints. require special attention because recommendations. DESIGN EXAMPLE l-EXTERIOR TYPE 1 JOINT distribution and joint deformation on the behavior of statical- ly indeterminate structural systems.l&Effect of slabs with 3 No. cretes. In all of the examples. high seismicity will experience significant inelastic defor- mations. which are usually present at strates the application of the committee’s joint design the roof level of a building. thus making the construction process very difficult.+” spondfel Bmm. top stUdies. has rent design guidelines do not conform to the cumnt require- been used in construction of columns.48~5*~~~62. IS” x 30” A.14-Joints in existing structures 5500 psi (38 MPa).13 plastic hinges away from the face of the column and for eval. These joints need to be studied in detail to establish mendations were not developed for such high-strength con.ll-Steei congestion OF CONNECTION Type 2 connections in many structures require a signifi- cant amount of steel. Each example pre- limited to connections in which the column continues above sents given member sizes and reinforcement and demon- and below the joint. no definitive con- clusions have been developed on how the presence of a slab affects the requirements for confinement and the moment ca- Nomol Bwm pacities of the beams. material strengths. Means to reduce steel congestion need to be studied and recommendations need to be made. that is. ing lateral loads.53 APPENDIX B-DESIGN EXAMPLES A. it is assumed that both column and beam longitudinal reinforcement may ter.65 A. t I bon. The compressive strength of the concrete used in test specimens varied from 3500 psi (24 MPa) to approximately A. primarily obtained from tests of statically determinate joint assemblies. 24”X 24” with 12 No. Experimental data are needed to quantify these effects. Joints in structures built prior to the development of cur- with compressive strengths up to 19. duce the required confinement steel in the joint or to increase the maximum allowable shear capacity of the beam-column A. 10 bon. these recom. limits can be raised. . There is a need to establish the effect of force re.63~~ However.9-Lightweight aggregate concrete Additional studies are needed to evaluate all aspects of joint behavior where various types of lightweight aggregate umn. The contribution of the slab to stiffness and strength of I \Normol Boom. ments. Ex. The examples are similar specimens.&High strength concrete in the joint configurations. The current limits on joint shear are overly conservative in the opinion of many designers for certain combinations of A. etc. tl ban concrete is used.g-Behavior of indeterminate systems affected the design of these joints is given at the end of this Experimental results for beam-column joints have been appendix.4244. Clearly. top. elastic analysis. BEAM-COLUMN JOINTS 332~. PLAN VIEW A. In recent years high-strength concrete.12-Distribution of plastic hinges uating the capacity of the connection when such details are Not all the joints within a structure located in an area with used. Research is needed to evaluate the behavior and capacity of high-strength concrete joints. their adequacy. 24 in. (Sec. between sets of ties should be less than or equal to 6 in. typical transverse reinforcement is required. use y = 20 from Ta- ble 1. the max- Hooked bar anchorage (Section 4.)(0. battun 0. Spacing bi = (24 in. 12” X 24* a = A. 9 tars. 11 bars is accept.0.*)( 1.85f. 4 ties is shown.afy= 4 1.2.352~. + 21 in. DESIGN EXAMPLE 2-INTERIOR TYPE 1 JOINT .85 (4 ksi) (21 in.2(a) applies.56 in. Tu = A.) Joint shear force (Section 43.1.1) V” = 683.2. (OK) 1. so mod I& = (26. T -mi -- The reduction factor of Section 4.2.3). vrl = 20 &%&i (22. . ’ 4000 ps’ ham.‘b 0.1) imum possible joint shear is a function of the flexural capac- ity of the beam normal to the connection.1.5. Transverse reinforcement (Section 4. This is an exterior Type 1 joint which meets the geometry able.8 in.7 in. = 20 8 bj h(c01) vri tion 4.5 in.2. Spacing be- tween sets of ties should be less than or equal to 6 in.14 MANUAL OF CONCRETE PRACTICE Column longitudinal reinforcement (Section 41.2.3.C&unn.2) The arrangement of eight No. Therefore.5 in.2.O)‘ (60 ksi) fy*eo ksl with 3 No. IO bars.3). and 3 No. 12’ Available space = 24 in. 14 bars shown above is ac- ceptable.85 (683 kips) = 581 kips > 315 kips (OK) tion because large unbalanced moments are not anticipated in this direction.1) Neither beam covers three-quarters of the column width.(ioint) = T. restrictions of Section 4.56 in.5 in-)(24 in. 24” X 24” dth 8 Ma I4 bofs r. (tie diameter) = 22 in.7) = 18. Transverse reinforcement (Section 4.Vcor = 3 15 kips moments are not anticipated in either direction.000 lb = 683 kips Shear is not a problem in the transverse (spandrel) direc. . (Sec- tion 4. 4( 1.)/2 = 21. . top. Therefore. (back cover) . For shear in the normal direction. A Vu (joint) permissible arrangement of No.5 in.5.* ( I .0)(60 ksi) Iu. 4 ties is shown. = 708 k-ft v co1 = M&eam)/l2 ft = 59.1.) 5..1) A permissible arrangement of No.1.2) Joint shear strength The indicated arrangement of twelve No.0 kips PLAN VIEW Joint shear OF CONNECTION Longitudinal &am Column longitudinal reinforcement (Section 4. a& = 374 kips Shea+-Shear is not a problem because large unbalanced V. = 8490 k-in. cbvn = 0.2. \ fjatisfks oil of tha raquimmanfs of comes from two times the clear cover (typically lYz in. (i) (2) (3) spacing > 3db. in.4 f yh 11 1. joints based on size of longitudinal reinforcement 60ksi [(21 in. 10 bars.20 in?/leg) No.2.1 from Eq. 1. and 3 No. 10 bon. 9 to satisfy Se& Table B.0 from Eq.2).8 10 1. 8 ban. 6 0 750 15.2. For column hoops at a For column hoops at a Ash = 4 legs (0.9 Shear (Section 4.1.27 20.69 33. in. reinforcement.2 14 1.3.4). BEAM-COLUMN JOINTS 352R-15 Anchorage-Top beam bars should be continuous through Column. f. (4.2 (OK) based on size of column longitudinal Bar size.3 25. The 20 percent reduc- tion factor for close spacing of transverse reinforcement is included in Column 5 of Table B.) (21in. These tables should be useful for select.) (4ksi) (24in. Wider ond 3 No.og. dt.8) using 01= 1.2) 9 1.h”f.13 17.6 19. It is recommended that bottom bars also be contin.2. in most loca- DESIGN EXAMPLE ?-EXTERIOR TYPE 2 JOINT tions.2-IMmhnum column or beam depth for ‘Qpe 2 A .2 (OK) 10 I .5. THE JOINT Values for Cd.2 < 0.750 11. tion 4.2 is based on re- quirements for the ratio of joint dimensions (actually beam and column dimensions) to the diameter of beam and column i-+Spondd f3aam bars (Section 4.756 in? < 0. PLAN VIEW OF ing main reinforcing bar diameters and joint dimensions. spandrel beam from three No.7 in.3 14. an extra 3$ in.1Minhnum column depth for ‘Qpe 2 joints based on anchorage of terminating beam longitudinal reinforcement Transverse reinforcement (Section 4.5 8 1. assume d Preliminary design = h . minating in a joint (Section 4. Table B.7 in. bottom Before starting the examples for Type 2 joints.41 22. top system for resisting lateral loads. In Table B. ~=6* has been added to Idh to determine the minimum column di- mension required to anchor a given bar. 10 bars. in.3 sr=03(6in.2).2. bottom beam sections will be necessary to cover the column faces Anticipated change-Change the top reinforcement in the and thus allow the use of higher shear stress values.771 in.’ = 4ooo psi uous through the joint because the joint is part of the primary fy = 60 ksi Spandrel Beam. 18” X 30” with 3 No... 1.3 and back) plus one tie-bar diameter. top column sections than have previously been required.4 (Table B.25.’ 9 1.2) Provided h(min) for column syz db in. (4) spacing 5 3db in.8 21. 24” X 24” with 12 No. ignore the effect of compression reinforcement and assume. (4..3) 7 0:875 17.8 19.0 s.8 17.875 13.27 25.80 in.2) The arrangement of twelve No. were calculated from Eq. No.2 (each direction) 6 0.3 16. Column longitudinal reinforcement (Section 4. In locations where there is interference between bars from the normal and spandrel beams. Table B.5. = 0.80 in.41 28.1 23. The quantity 3$ in. (4. front saetion 4. I I &S the joint. in the spandrel beam. 21” X 28” quirement. (5) A sh = 0.00 20. 1 is based on anchorage requirements for bars ter. &. 4 tias fY = 60 ksi and& = 4000 psi.9 15.6 11 A sh 1. . saonl No.j2-‘l h(min) for column based on size of heam longitudinal reinforcement of h(min) for heam Ash = 0.5. in.00 15.0 7 0.8 21. \Normol Beam.3 17.4 13. it is impor- tant to point out that to satisfy the anchorage and shear re. d = h . 10 to four No.6 8 1.3) For the bending analysis which follows.80 in.& a designer will probably have to use larger with 5 No.6 A sh = o. 11 bars acceptable..)2 ‘lhble B.13 22. )/2 = 22. = (0. c$.Vco.85 (4 ksi) (21 in. 2 5 ) ( 6 0 k s i ) aI = 0.4) Aslafy 4 1.*)( 1.‘(beam) = (6. .25)(60 ksi) = 178 kips V.25)(60 ksi) (25..67 inA) Ki = 7 160 k-in.‘b= 0. V.)(24 in.Vco.* ( 1. (gov- V. = Y &m bj h(COl) ems). 0.25) (60 ksi) = 5Asort. .*)( 1. 2 7 in.= 0.‘b . = 383 k-ft Then 0 “col.00 in.) 41 = 4..5 in.0 in.‘(beam)ll2 ft = 72.(joint> = T. + Cu2 . = 596 k-ft M.25)(60 ksi) = 300 kips 15 (Table 1).3 in./=(M”./12ft=81.352R-16 MANUAL OF CONCRETE PRACTICE Normal direction Spandrel direction 1 \ Assumed ~kE:c% 1 rlc t2 Points in the Cobmn %i = As.500 k-in.3 in.‘(beam) = 10.* ( 1 . = A.‘(beam) = Asa&( d .6 kips Similarly Joint shear Mni = 4590 k-in.)/2 = 21. = 3% kips bj = (bb + bc)/2 < bb + 2[h(CO1)/21 = (21 in. c u2 = Tl42 = (2.afy M.35 in... + 24 in. .90 in. = 404 kips Joint shear strength-The spandrel beam dimensions are sufficient for classifying this as an exterior joint.000 lb = 512 kips $V.6.00 in. +M.(joint) = T.)(24 in.6kips Joint shear Vu (joint) F Vu (joint) T.*)( 1. = 872 k-ft VCO1 = M.85)( 15) Am(21 in.67 in.*)( 1.5 in. 1 . bj = (18 in.‘T M.85f. Ki a = (4.25)(60 ksi) 26. = 476 kips V. and = 15 dm (22. = 6.) +V.. (governs) In this direction.) a OMf. so use y = TUl = (4.85 (5 12 kips) = 435 kips > 404 kips (OK) = 406 kips > 396 kips (OK) .37 in.) ab = 512. + 24 in.85 (4 ksi) ( 18 in.00 in. 41 in. the axial load was assumed to be zero (conservative for this check). < 24 in.= 2.2 in. tOP No.2. 11 bars is accept- able.20 in. (OK) Transverse reinforcement (Section 4.13 in.5.3) may be reduced by 50 percent in the joint. (b-) = 477+306 Tlormu” 6ooq 21-x 25 PLAN VIEW OF with 3 No. 10 bars for the normal beam need to be checked.6 in. Referring to Table B. 10 hors. 3. Ii bars. and use the same I.80 in. Using these assumptions. the required column dimen- NO.2.6 in. IO ban. The depth of the transverse beams is set differently than the depth Spandrel direction of the longitudinal beams to avoid reinforcing bar interfer- CM. h(beams) > 20 (1. M. (say OK) Because beam dimensions satisfy Section 4. 9 bars.4. The width is increased to help satisfy con- = .5.1. 2rx30- 5 No. 10 bars. = 848 k-ft. (4..5. Change transverse beams to 21 x 28 in. bottom a = 1.25 to obtain an approximate value for the beam flexural strength if Beam.2. with 4 No. = 2. I 872 k-ft/l. h(co1) > 20 (1.5 = 477 k-ft No. (col) 2(848) reinforcement.17 > 1. 14 hors Also.. DESIGN EXAMPLE 4-INTERIOR TYPE 2 JOINT From EZq. Change column to 28 x 28 in.2) and (4. IO bars.5. The beam bar diameters are decreased to satisfy Section Strength ratio check 4. = 28 in.3 Beam and column bars passing through the joint (Sec- tion 4. 11 bars.2) The total beam depths are governed by the column bars Provided A. and use twelve No. bottc4n Hooked bars terminating in a joint (Section 4. the val- ue for Ash obtained from Eq.25. t6” X 26” a = 1. IO bms. 2.25 = 306 k-ft creased to help satisfy confinement and shear requirements. bona mqulmmonl of wcWm 4. 10 bars as top reinforcement. 9 bon.4) The No. The beam width is in- Mn2 z 383 k-ft/l. top a more accurate determination of the beam flexural strength 4 No.*/leg) = 0.) = 28. Transverse Beam. Change longitudinal beams to 21 x 30 in.. Anticipated changes Normal direction 1. The dimension increase is required to satisfy shear and M. 24*X 24” with 6 No. z 596 k-ft/1.2.5.O could be made. 1. top ond 3 No.2.4 and the beam depth is increased to satisfy Section 4. bottom for a = 1 .4 for the column bars. If the strength ratio is close to the allowable value.O for this calculation.2) size The indicated arrangement of twelve No.4 (OK) q 0-d 698 finement and shear requirements and the beam depth is in- creased to satisfy Section 4. 12” X 24” The beam flexural strengths have been found earlier using with 3 No.2) Preliminary design When determining the column flexural strength.0.4 (OK) =f. (4. 9 bars in the spandrel beam govern the column Column longitudinal reinforcement (Section 4.25 = 698 k-ft bar development requirements.4 Normal direction for the column bars. = 4 legs (0..* (each di- rection). (col) 2(848) ence. c’ udiml born.2) .43 > 1. and use five M... IDO !j&fi.din all the and 4 No.2) REVISED JOINT Only the No.5. Those beam strengths will be divided by 1. a was set equal to 1 . BEAM-COLUMN JOINTS 352R-17 Flexural strength ratio (Section 4. Column.2. 4 sion is 23.) = 22. which is less than the provided dimension of 4’6 24 in.M. The increase in the number of longitudinal bars is required to give a more uniform distri- Spandrel direction bution of longitudinal steel. = 951 k-ft M.3) bi = (28 + 21 in. Other significant changes were the increases in beam widths to better confine the joint and decreases in A Vu (joint) beam bar sizes to reduce the tendency of bars to slip through the joint during earthquake-type loading. quired amount of transverse reinforcement in the joint. I 28 in. 1 (metric) and B.27 in?)( 1.25)(60 ksi) 27.. (OK) M.*)( 1.q) h(beam) > 20 (1.90 in?) = 0.&’ bj h(COl) selection of joint dimensions when using standard metric . TIll = 5 (1.2) Thus.= 761 + 626 = 1.2 (metric) are given to aid in the Vn = Y .352%18 MANUAL OF CONCRETE PRACTICE A sh = 03(6”) - (25”) (4bi) (28)* 60ksi (25)* -[ -1 1 = 0763in2 * * The beams have been made wide enough to classify this as an interior joint. use of the new committee design recom- mendations led to no changes from the prior committee “co1 reportI for these design examples.) = 28.4.. =782 k-ft Comparison to the results of the previous committee re- Vco1 = (Mn{ + M.2 c 0.5 inJ(28 in.5 (0.27 in?)( 1.5 > 1.4 (OK) Beam and column bars passing through the joint (Sec- tion 43. = 9380 k-in.0 am approximated as Shear (Section 4. (col) 2 (1070) Flexural strength ratio = “M. + C.. (bei.2 in.z .. = 1070 k/ft.400 k-in.41 in.3 in. and for Examples 3 and 4 there was a large decrease in the re- cu27 “” STTU.25)(60 ksi) = 476 kips c = Tu* = 4 (1. = 4( 1.. < 28 in.. Only the longitudinal beams need to Clearly the longitudinal direction is critical because of the be considered because they are stronger than the transverse larger beam steel area and the larger beam depth.3 .27 in. the col- and the minimum tie size for a No.4 in. For the Type 2 joint ex- / amples there were some significant differences.)sb * 60ksi = 738 kips > 713 kips (OK) Required As.25 = 626 k-ft ZM.) = 25.) Using the same assumptions used in Example 3... &I. .9 > Beam depths are controlled by the column bars A4.45 in.2)( 1.25 = 761 k-ft Mn* z 782 k-ftD..25)(60 ksi)( 27. = 5( 1.4) The column dimension is governed by the largest beam bar h(co1) > 20 (1.5 in.. Beam flexural strengths for a = 1. (say OK) lu./m (24.Vcol = 713 kips Tables B. 11 bar govern the design.25)(60 ksi) = 38 1 kips SI METRIC TABLES AND EXAMPLE V$oint) = T..80 in2 (OK) Flexural strength ratio (Section 4. c bb + 2[h(col)L?] A sh = 009(6”) (25”) (4W = 0900in2 wfl = (0.3) was done in Example 3.)/2 = 24.85)(20) ..27 in. These changes clearly reflect the committee’s current philos- ophy of requiring larger columns (joints) and less transverse reinforcement. = 11. umn flexural strength is M. 5951 k-ftA.i )/12 ft = 144 kips pod For Type 1 joints. = 0.27 in. so y = 20 (Table 1) From Eq.. (4.. Changes were required in the column (joint) size for Example 4. for this joint the maximum allowable spacing (6 in. Using the beams same assumptions for the flexural analysis as were made in the previous example. Column. No. fofcement in the spandrel beams satisfies the requirements of umn 5 of*Table B. The rein- resents two times the clear cover (typically 40 mm) plus one forcement in the normal beam satisfies the requirements of tie bar diameter ( 15 mm). (4.5 390 25 25. (4. 30 bars.2 (metric)-Minimum column or beam depth A sh = 03(150) * (520) (30) (600)2 1 =582=2 400 for ‘Qpe 2 joints based on size of longitudinal (520) * reinforcement < 800 mm2 (OK) h(min) for column based on size of beam longitudinal reinforcement or h(min) for From JZq. allow this joint to be classified as an exterior joint.0 236 331 320 20 19.l (metric).3) beam based on size of column longitudinal Bar size.1. In Column 4 of Table B. an extra 95 mm has Notes on joint geometry--Dimensions of the spandrel and been added to 1. mm mm For column hoops at a For column hoops at a (2) (3) swing > 34. joints based on anchorage of terminating beam bars I Column longitudinal reinforcement (Section 4..3) metric dimensions and units for beam-column joint design.3 [Column 4 of Table B. 450mm X 750mm. The 20 percent reduction factor for Section 4. (mm) (5) Ash = 4 legs (200 mm2ileg) (1) Ash = 800 mm2 15 16.mm reinforcement. 35 bars is acceptable. db. For the bending analysis. Section 4.0 320 20 19.5. reinforcement and in most locations assume d = h . (mm) (4) spacing 5 3db. w i t h 6 No.7 874 = 527 mm2 < 800 mm2 (OK) Design example 3 (metric) is included to show the use of Shear (Section 4. 25 bars.-1 35 35.7 714 45 43. with 8 Normal Direction* f:=3ohlPa I/ “co1 No. 30 bars. top \ T and 3 No.. (5 at 150 1 I Inflection Point “col (Assumed) l 1 MPa = 1 N/mm’ . 30 hors.2) 25 25. mm 15 16.5 287 382 325 From Eq. d. dimension required to anchor a given bar.2 (metric)]. bottom Normal beom. bottom 3.7 526 621 516 Table B. 5OOmm X 750mm. 1 (metric).2) Bar h(min) for column size. top o n d 4 No.2.2.100 mm in TYPE 2 JOINT the spandrel beam.9 598 35 35. BEAM-COLUMN JOINTS 3!52&19 bars. 35 bors Inflection Spandrel beam. Point with 4 No. when determining the minimum column normal beams.4 [Table B. In locations where there is interference between bars from DESIGN EXAMPLE 3 (METRIC)-EXTERIOR the normal and spandrel beams.9 440 535 447 [ . This quantity rep. & Provided No. ignore the effect of compression This example is very similar to Example 3. Transverse reinforcement (Section 4.70 mm.5 m 1 MA PLAN VIEW O F JOINT No. when compared to the column dimensions.2) Table B. 600mm X 6OOmm.l (metric)-Minimum column depth for ‘Qpe 2 The arrangement of twelve No. The rein- close spacing of transverse reinforcement is included in Col.l (metric)].2 504 30 29.2 371 466 392 30 29.5. assume d = h . and Point \ T $V. = (0..0 for this calculation.85 (30 MPa) (450 mm) = 122mm VTu = (2800 mm2)( 1. bj = (450 IIUII + 600 mm)/2 = 525 IYUII Inflection (governs).25 to 1 obtain an approximate value for the beam flexural strengths when a = 1 .Vcor = 1740 kN Joint shear srrengrh-As previously determined.=A. Ql 0 =0. and a was set equal to 1.5m load was assumed to be zero (conservative for this check).25)(400 MPa) = 1400 kN C u2 = Tu2 = (1500 mm2)( 1.85f.85 (30 MPa) (500 mm) = 165mm M.rn/1. the axial 3. + Cu2 . lnf lectioh Normal direction Paint M.85f. Those beam strengths will be divided by 1. so use y = 15 (Table 1) 65. + M.afy (d-i) a Asafy 6 700 mm2 ( 1.=21OOkN a2 0. =O.O.5 m = 359 kN Joint shear bafy 4 700 mm2 (1.‘b= 0.. Using these assumptions. . m..43) When determining the column flexural strength.083 (15) &if%ii% (550 mm)(600 mm) TIll = (2800 mm2)( 1.25) (400 MPa) “col. this is an wli = (1500mm2)(1.mm=463kN.85 (2250 kN) = 1910 kN > 1743 kN (OK) Spandrel direction In this direction.‘b= 0.1125OkN..25) (400 MPa) =0. The beam flexural strengths have been found earlier using a = 1.25) exterior joint.‘(beam)=1.25)(400 MPa) = 750 kN =2250x 103N=2250kN V.af.(joint) = T..(joint) = T.4 mm (4OOMPa)(650mm-- 2 > bi = (bb + bJ2 < bb + 2[h(co1)/2] = (500 mm + 600 mm)/2 = 550 mm (governs) =463x106N.25x109N~mm=1250kN~m Vco1 = Mn’(beanQl3.O83 Y off bjh(COl) V CO1 = (M.- 2 Vu (joint) = 3 500mm2 (1..85 (30 MPa) (450 mm) * V.25= 1OOOkN~m . M.Vcor = 1780 kN W” = 0.m v. = 1075 kN .083)( 15) d%%l% (525 mm)(600 mm) =2150x 103N=2150kN> 1780kN(OK) Flexural strength ratio (section 4.25.25)(400 MPa) ( 680 mm-y) Vu (joint) M.25) 122 mm (400 MPa)( 650 mm .‘(beam) = (4200 mm2)( 1.85)(0... )/3.‘(bem)=A.5 m = 368 kN = 0..2!52R-20 MANUAL OF CONCRETE PRACTICE Joint shear M.25) (400MPa) =654mm T. .m/1.5. m CM. = 2 YE) = 2. z 867 kN .2 (metric). BEAM-COLUMN JOINTS 352R-21 Spandrel direction CM” (col) = .4 (OK) =f.99 > 1.5.8 = 1. m/l..gyy. (b=W This report was submitted to letter ballot of the committee and approved in accor- Spandrel direction dance with Institute procedures.2 and Strength ratio check 4.l (metric) and B. (col) Tables B.25 = 694 kN ..15 > 1.4 (OK) M.25=388kN..4) As mentioned previously.. the joint dimensions were se- Normal direction lected to satisfy these requirements which are summarized in CM. (t-4 Mn~~485~.m Hooked bars terminating in the joint and beam and col- umu bars passing through the joint (Sections 4. .
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