Global Probabilistic Seismic Demand Analysis Of Reinforced Concrete Frame Structures

Earthquake motion, seismic demand and seismic capacity are three cornerstones of Performance-Based Earthquake Engineering (PBEE) theory. The relationships between seismic demand parameters of engineering structures and earthquake motion intensity measures are called seismic semand models. Since the seismic activity is random in nature, and the earthquake motion is a stochastic process; what's more, the structural model and its parameters are random due to both aletory and epistemic uncertainities, therefore, the structural seismic semand model is also random in nature. Probabilistic Seismic Demand Analysis (PSDA) is the subject which sets up the probabilistic relationships of seismic demand parameters and earthquake motion intensity measures, and the results of PSDA is named Probabilistic Seismic Demand Models (PSDM).Probabilistic seismic demand analysis of engineering structures is the foundation of structural seismic reliability analysis, structural seismic fragility analysis and structural seismic risk analysis; meanwhile, it also is an important part of probabilistic performance-based seismic design and assessment of structures by using the full probability (level-3) method. On the other hand, the results of PSDA can also provide scientific basis for earthquake loss estimation and earthquake disaster mitigation decision-making. Therefore, it is very important to apply PSDA in civil engineering structures and infrastructure systems.Under the probabilistic decision-making framework of the new generation of PBEE proposed by Pacific Earthquake Engineering Research Center (PEER), this study uses the peak value parameters (PGA, PGV and PGD) and spectrum parameters (Sa, Sv and Sd) of earthquake motion intensity measures as the input variables of PSDA, and takes the Inter-Storey Displacement Angle (ISDA), Roof Displacement Angle (RDA) and equivalent single-degree of freedom displacement ductile coefficient (μd) as the global seismic demand parameters of structures. 100 actual seismic motion records are selected according to different epicentral distances and magnitudes, and then the dynamic time history analysis based on nonlinear fibre beam-column elements is used as the computational tool for PSDA. From the two viepoints of only considering earthquake motion variations and simultaneously considering structural parameter variations as well as earthquake motion variations, two PSDMs of the reinforced concrete frame structures, namely logarithm linear regression model and response surface model, are set up. Combined with Probabilistic Seismic Hazard Analysis (PSHA) results of the site, the hazard and fragility of the global seismic demand are analyzed thoroughly and systematically.The main conclusions of this thesis are as follows:1. Compared with the case of simultaneously considering structural parameter variations and earthquake motion variations, the case of only considering earthquake motion variations is more conservative than the former.2. Compared with the results of PSDA based on peak value parameters of earthquake motion, the results PSDA based on spectrum parameters is better.3. It is found that threre is a certain difference in PSDMs based on logarithm linear regression model and response surface model. It is indicated by the hazard curves and the fragility curves that PSDA depends on PSDMs.