Although most structural systems are designed as a series of individual elements, they will in fact respond to load as a rather complex integration of these elements. the load is transmitted through acombination of members which resist loads in proportion to their relative stiffness. these types of structures are said to have multiple load paths. redundant load paths have not been normally consideredin the design of structures. however, the consideration of secondary load paths can be a major factor in the assessment of the load carrying capacity of a damaged structure. this paper takes a further look at the reserve strength present in a multi-girder bridge system, and investigates the behavior of a damaged superstructure, the redistribution of loads, and the secondary load paths along which the load is transmitted when a damage occurs in the structure. limit analysis was used to predict the overload behavior of a simply supported concrete slab-steel girder highway bridge system. the bridge superstructure was modeled as grid and grid framework elements. the experimental results from tests to failure on four large scale bridge modelswere used to verify the computer approach. in order to study the response of a distressed bridge, a mathematical model consistng of four girders was analyzed. three different finite element models were used to investigate the following conditions: (1) no damage in the superstructure; (2) localized flange losses in a girder; and (3) crackin a girder. results are given in terms of load deflection curves for the three models. this paper appears in transportation research record no. 1290, third bridge engineering conference, march 10-13, 1991, denver, colorado, volume 1.
Samenvatting