PSI - Issue 70

Ajisha T T et al. / Procedia Structural Integrity 70 (2025) 27–34

30

Earthquake magnitude selected ranges from 6 to 8 Richter, Shear wave velocity ranges from 0 o180m/s for thes oft soil condition as shown in fig 3.

Fig. 3. Scaled ground motion according to design response spectra.

Table1.Nonlinear parameters considered in NLTH Aanalysis

TypesofFrames

1 st mode frequenacy

2 nd mode

Massc oefficient

Stiffness coefficient Mo

frequnacy

Model1 Model2 Model3

0.271 0.256 0.223

0.286 0.278 0.251

0.087 0.073 0.067

0.029 0.024 0.019

4.2. Nonlinear parameter

Toper form nonlinear dynamic analysis P delta and large displacements are considered. Gravity load, the load combination of 1.0(D. L+L.L) is to be applied to the structure before NLTHA. The expressions form as matrix and stiffness matrix multipliers are Mass coefficient = 2 ∗ ₁ ∗ ₂ ₁ + ₂ ∗ Stiffness coefficient = 2 ₁+ ₂* Where, ₁ and ₂ are the first and second mode frequencies of the structure e and is viscous damping considered 5% for all the models. 4.3 NLTHA Procedure It is a structural dynamic analysis procedure used to simulate and analyze the real-time seismic response of a structure under applied ground motions. Following procedure is adopted to perform the NLTHA in SAP2000 software. 1. Import the scaled and matched time history ground motion database obtained from Seismo Match 2016 software to SAP 2000 software as time history functions. 2. Time history load cases are defined under each selected ground motion functions seperately for load type acceleration (U1) keeping scale factor equal to 9.81 in order to convert unit of of (g) into m/s. 3. A total number of time steps and step size for each time history functions are mentioned as per the number acceleration values recorded at regular time intervals. For example, in fig..The time steps and time intervals for Loma Prieta time history data files are 2985 at a time interval of 0.01 seconds is mentioned in time step data. 4. Finally save and run the analysis. Extract the output data in term so lateral story displacement, IDR, plastic hinges, etc. and evaluate the seismic performance of the structure corresponding to the performance levels.