Effects of load histories on reliability analyses based on nonlinear finite element analyses of reinforced concrete structures

Abstract

The effects of load histories on reliability analysis using nonlinear finite element analysis (NLFEA) of reinforced concrete (RC) structures was studied in this thesis. Using a finite element software, several NLFEA on an undetermined RC frame was performed with various combinations of a vertical and horizontal load. The global failure mode of the frame for all analyses was concrete in bending. Ultimate design capacities was calculated according to three safety format methods, the partial safety factor method (PSFm), the global resistance factor method (GRFm) and the method of estimation of a coefficient of variation of resistance (ECOV).

A solution strategy for NLFEA was developed based on NLFEA guidelines provided by the Rijkswaterstaat Ministry of Infrastructure and the Environment. The solution strategy was verified by comparing NLFEA predictions to predictions from a calibrated NLFEA solution strategy.

Results show that the load histories influenced the estimated design capacities of the safety format methods, and that the initial loading condition was found to be the greatest source of influence. The degree of influence varied between methods, with GRFm being most affected and PSFm the least. Furthermore, initial loading had an inverse influence on the GRFm compared to the influence on ECOV and PSFm.

The results of the thesis represent only a small population and further analyses are necessary to map the effects. Such analyses should include other failure modes, such as shear or punching shear failure.

Key words: Nonlinear finite element analysis, NLFEA, safety format, reinforced concrete, load history, design capacity, structural reliability