Abstract
Many in-service bridges with steel–concrete composite beams are currently aging and experiencing performance deterioration. Under long-term cyclic loads from traffic on bridges, headed shear studs in steel–concrete composite beams are vulnerable to fatigue damage. The comprehensive understanding of fatigue behaviors and the feasible detection of fatigue damage of headed shear studs is, thus, crucial for the accurate numerical simulation of the fatigue crack propagation process. The paper, thus, experimentally investigates the fatigue behaviors of headed shear studs through push-out tests of three specimens. The fatigue failure modes and cyclic strain evolution of specimens are analyzed. The fatigue lives of headed shear studs are compared with the S–N curves of the AASHTO, Eurocode 4 and BS5400 codes. The fatigue crack details of shear studs in push-out tests are then detected using the ultrasonic non-destructive testing. The results show that the root fracture is the main fatigue failure mode of shear studs under fatigue loading. The fatigue life estimations based on the three current codes (i.e., AASHTO, Eurocode 4 and BS5400) can be safely guaranteed only with different safety redundancies. The strain at the shear stud with fatigue damage shows a consistent increasing trend followed by decreasing behavior after reaching the peak value with the loading cycles. Moreover, the feasibility of the ultrasonic non-destructive testing with the combination of a strain measurement for fatigue crack details detection of headed shear studs in composite beams is proved.
Highlights
The study provides insights to assist in developing an accurate numerical simulation of fatigue crack propagation of headed shear studs in steel–concrete composite beams
The global failure pattern of all specimens was the fracture of headed shear studs without a large area crushing and cracking of the concrete slabs, leading to a separation between the concrete slab and the H-shaped steel column on one side (Figure 6a,d,g)
It can be found that the push-out test results were closer to the S–N curve of the BS5400 than the other two curves
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Okada et al [14] studied the failure mode and shear strength of grouped shear studs based on a push-out test of shear studs and numerically simulated the test results using the finite element analysis. Their numerical models provided a better understanding of the different failure modes observed during experimental testing and, the shear capacity of headed shear studs. There is no effective non-destructive detection method to monitor the fatigue crack details of shear studs, which limits the development of a numerical simulation of the fatigue crack propagation process In this case, a series of cyclic push-out tests are conducted to study the detailed fatigue behaviors and the feasible fatigue damage detection of headed shear studs in steel–concrete composite beams. The study provides insights to assist in developing an accurate numerical simulation of fatigue crack propagation of headed shear studs in steel–concrete composite beams
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