Numerical analysis on the moment redistribution behavior of prestressed continuous beams considering the effect of construction method

Abstract

The design method for the prestressed continuous beams (PCBs) in the current design codes usually neglects the effect of construction method, which determines the distribution of initial internal forces caused by dead load in the PCBs. To fully investigate the moment redistribution behavior of the PCBs constructed by monolithic casting (MC), simply supported-continuous (SC), and cantilevered-continuous (CC) methods, a simplified but effective numerical analysis method was proposed by combining the modified force method and incremental method, in which the effect of initial internal forces and secondary moment were isolated and discussed. The proposed numerical method was first calibrated by the test results, and then used to predict the mechanical behavior of 27 PCBs during the whole loading process with the parameters of construction method, the effective prestressing stress in the prestressing tendons (fpe), the degree of prestressing (PPR), and the relative neutral axis depth (ξ). Based on the analysis results, it was observed that the initial negative and positive bending moment in the PCBs produced by different construction methods helps improving the moment redistribution ability of the sections with maximum negative and positive bending moment, respectively. Besides, the current design codes generally overestimate and underestimate the ultimate bearing capacity of the simply supported-continuous and cantilevered-continuous PCBs, respectively.