Studies of the lifetime of cyclically loaded steel-concrete composite bridges

Abstract

In current German and international standards for composite structures of steel and concrete, the determination of the ultimate load capacity and the fatigue life of headed shear studs is carried out with separate and independent verifications at the ultimate, serviceability and fatigue limit states. The fatigue resistance is verified in a similar way to steel structures, based on a nominal stresses concept and linear damage accumulation according to Palmgren‐Miner. The effect of pre‐damage due to fatigue loading at both the ultimate and serviceability limit states is not considered. Because cyclic loading of headed shear studs leads to a decrease in the static strength of stud connectors, the assumptions for independent limit states are not given and the reliability index of steel‐concrete composite structures subjected to fatigue loading may fall below the target values in codes. This paper deals with the results of a comprehensive programme of experimental work with more than 90 standard EC4 push‐out test specimens and two full‐scale beam tests which consider the crack propagation through the stud foot and the local damage to the concrete surrounding the studs as relevant consequences of highcycle loading. Based on the results of the push‐out tests, new design methods were developed to predict the fatigue life and the residual strength of headed shear studs after high‐cycle loading. Considering the interaction between the local damage and the behaviour of the global structure, these research results were taken as the basis for simulating the cyclic behaviour of composite beams by means of a damage accumulation method.

Elastic behaviour of a tapered steel-concrete composite beam optimized for reuse

“…The experimental load-deflection curves that were obtained by Gogoi [28] are almost identical for all beams, whereas the relation between applied load and end-slip differs significantly. A similar observation is made by Leskelä [29] in the work of Hanswille et al [30]. These observations imply that no reliable prediction method for end-slip exists, and that it is unclear how the relatively large difference between the experimentally and theoretically obtained end-slip can be explained.…”

Probabilistic Design of Composite Girders Considering the Degradation of the Shear Connection and the Redistribution of Forces

“…Using cyclic stresses, cyclic stress intensity factors can also be determined, Figure 4 c). Equations ( 4) and (5) were derived in [12,13] for composite dowels based on numerical parameter studies [14,15], where nominal stresses were replaced by shear stresses, considering the amplitude of dowel forces ΔP, the dowel spacing ex, the web thickness tw and one function Y both for crack and component geometry. Possible values for Ym and Yb are given in chapter 3.…”

“…This information can be implemented in the lamella model. Approaches for shear studs can be found in [4,5].…”

“…Figure 1b) shows this development for shear studs. Due to the large notch effects of the weld collars of shear studs, recent research projects assume crack propagation almost from the first load cycle [4,5]. The lifetime prognosis shown is based on the consideration of the mean values and thus forms the 50% quantile.…”

Fatigue Experiment Study on Internal Force Redistribution in the Negative Moment Zone of Steel–Concrete Continuous Composite Box Beams

“…Therefore, the cumulative damage can significantly affect the fatigue behavior and structural safety of steel–concrete continuous composite box beams. Moreover, many experimental studies have shown that parameters such as the reinforcement ratio, stirrup ratio, and shear connection degree have a significant influence on the fatigue performance of such composite beams [ 12 , 13 , 14 , 15 , 16 ].…”