CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWERPLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 “SPEPC” (Shapoorji Pallonji EPC) & the “Client” has come to an understanding that International Standards “ISO: 3010:2012 – Basis for Design of Structures- Seismic action on Structures” will be used for calculation of seismic action on Structures / Buildings. Accordingly following methodology is proposed for seismic force calculation and design The Seismic shear for the structure will be calculated manually by equivalent static analysis using Clause 8.0 of ISO 3010:2012 & will be applied as static load (joint load) in the structural “STAAD” model as follows. 1. Seismic Base shear will be calculated in the two orthogonal directions ( Global X & Z directions in STAAD) for ULS & SLS separately based on the following equations (Cl.8.0, ISO 3010:2012) a. ULS-ULTIMATE LIMIT STATE (Cl.8.1a, ISO 3010:2012) Eq. (1) Eq. (2) i Page 1 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 b. SLS-SERVICEBILITY LIMIT STATE Cl.8.1 b, ISO 3010:2012) Eq. (3) Eq. (4) i 2. The various seismic parameters defined in the above equations are considered as below:A. Load Factors related to reliability of Structure E,u & E,s (Annex – A 1.2) The degree of reliability depends upon the importance of the structure. All structures of plant facilities will be categorized under “High “degree of importance as per Annex A.1.2-a. The corresponding load factors for ULS & SLS as per Table A.1 & A.2 are E,u = 1.5 Page 2 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 E,s = 1.5 B. Seismic hazard zoning factor kz, (Annex – A.2) As per Annex A.2 of ISO 3010 for “highest seismic hazard” region in the world zone factor of unity is to be considered. For Rwanda this factor will be different and this has to be obtained from the client in particular, applicable for the proposed site location. kz = xxxx C. Representative values of earthquake ground motion intensity k E,u and kE,s (Annex – A.3) The representative values of earthquake ground motion intensity kE,u and kE,s are described in terms of the horizontal peak ground acceleration as a ratio to the acceleration due to gravity. These ground motion intensity are evaluated on a statistical basis in terms of return period of occurrence with the available historical data , previous engineering practice & acquired experience. For ULS kE,u xxxx to be obtained from the client for a return period of 500 years For SLS kE,s xxxx to be obtained from the client a return period of 20 years D. Structural Factor kD (Annex – B) Structural factor kD is used to reduce the design seismic force or the shear force taking into the account of the ductility, acceptable deformation, restoring force characteristics and over strength of the structure. Structural Factor kD 0.33 0.5 Structural System Lateral resistance is provided by steel or reinforced concrete moment-resisting frames with adequate connection details and ductility of structural element Lateral resistance is provided by steel braced frames or concrete shear walls E. Normalized design Response Spectrum kR (Annex – C) This factor kR is the ordinate of the normalized design response spectrum provided as function of fundamental natural time period of the structure Page 3 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 considering the effect of soil condition based on the soil investigation report & damping property of the structure. Page 4 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 F. Fundamental Natural Time Period T The fundamental natural time period T, will be calculated as per Cl. 4.3.3.2.2 of BS EN 1998 (Eurocode-8) T = Ct . H 3/4 Ct = 0.085 for moment resisting concrete frames = 0.075 for moment resisting steel frames & eccentrically braced frames =0.050 for all other structures H , height of building from foundation or from top of rigid foundation up to 40 m Alternatively T = 2.√ d d , is the lateral elastic displacement of the top of the building in m due to the application of gravity load in horizontal direction (arrived from the STAAD model). G. Seismic Force Distribution factor kf,I & Seismic shear distribution factor kV,i (Annex – D) Page 5 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 This factor will be calculated based on the geometry of the individual structure following the stipulations. a) Calculation of Force, FG,i For Buildings / Structures: The gravity load and the vertical imposed load (0.3 times the total imposed load) of the structure at particular level is arrived by considering pinned joint supports at each beam column joint location at that particular level in a separate STAAD model file . For Equipment foundations: The self-weight of the equipment provided from the vendor data will be taken directly for computation of the force. b) Computation of Height, hi For Buildings / Structures: The height, hi at ith level is calculated from the base of the structure to that particular level. For Equipment foundations: The height, hi for equipment corresponds to the CG of the equipment. The CG is be specified by the vendor or will be taken at 0.5 times height of the equipment. c) Seismic Force Distribution factor kf,i & Seismic Shear distribution factor kv,i The seismic force distribution factor kf,i can be determined by The seismic shear distribution factor kv,i can be determined by Page 6 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 i 3. Seismic force / shear thus calculated is distributed to individual storey as joint loads in STAAD model as equivalent static load. 4. Seismic Action in the three mutually perpendicular axis (X, Y, Z) will be considered in the appropriate load combinations in STAAD file for analysis & design in ULS (Refer Eq. (1 or 2)) & SLS (Refer Eq. (3 or 4)) conditions as per Annex-E of ISO 3010:2012. 1) E = Ex +Ey +Ez E = Ex + Ey +Ez E = Ex + Ey +Ez The value of is taken as 0.4. Page 7 CALCULATION OF SEISMIC LOAD FOR 2 X 35 MW PEAT FIRED POWER PLANT PROJECT AT RWANDA, AFRICA AS PER ISO 3010:2012 2) Vertical component Ey is calculated considering vertical peak ground acceleration as 0.5 times the horizontal peak ground acceleration. 5. The design of steel and concrete structures will be carried out using EN (European) codes in Limit state method (LSM) Page 8