Due to the complexity and difficulty involved, the interfacial bond-slip relationship of externally bonded (EB) fiber-reinforced polymer (FRP)-to-concrete joints has been investigated, mainly through experimental testing. This work investigates the interfacial behavior using the finite-element method (FEM). Damage plasticity theory is employed to model concrete material and the pull-off test of EB-FRP-to-concrete joints is simulated by FEM to study the interfacial behavior. Debonding process, failure mechanism, local bond strength distribution, and characteristics of the local bond-slip relationship are examined. It is found that the local bond-slip relationship has a shape different from all existing bond-slip models. However, such change in shape does not make a significant difference to the global interfacial load-slip response.

High-performance concretes without steam curing have great potential to improve crack resistance in the hogging-moment regions of continuous steel–concrete composite beams. This paper conducts experiments to investigate the cracking resistance of hogging-moment regions of prefabricated composite beams consisting of steel–NSCs (normal-strength concretes), natural curing steel–UHPCs (ultrahigh performance concretes), or steel–UHTCCs (ultrahigh toughness cementitious composites). The tensile strengths of natural curing UHPCs and UHTCCs are first measured because the concretes are usually in the tensile state in hogging-moment regions. Flexural tests are then conducted to investigate several important parameters of steel–NSC/–UHPC/–UHTCC composite beams: deflections, initial cracking loads, crack propagation, interlayer slips, and flexural bearing capacity. It is demonstrated that relative to traditional composite beams, steel–UHPC composite beams without steam curing can effectively improve the hogging-moment bending performance such as increasing cracking load, reducing interfacial slips, and concrete slab crack width. Moreover, it is found that although the steel–UHTCC composite beams are not as good as the steel–UHPC composite beams in terms of initial cracking loads but have better performance in controlling crack widths and lengths. The effect of prestressing on steel–UHPC composite beams under hogging moment is also studied and demonstrated to be influential in further increasing the cracking performance in hogging-moment regions.

Owing to its light self-weight, low heat capacity and large thermal expansion coefficient, the application of the curved steel box girder bridge with small and medium spans has gained popularity for the construction of urban infrastructure. However, sun exposure could easily increase the maximum temperature difference at the bottom of steel box beam by 25°C. With the effect of nonuniform temperature field and overloaded vehicles, the edge inside the curved steel box girder bridge may be separated from the remaining structure, resulting in overturning. Thus, more attention needs to be paid in order to prevent the separation. In this paper, an overturning resistance analysis of a three-span curved steel box girder bridge located in Hangzhou, China was performed. A model was proposed based on the measurement of temperature field to the steel box girder. The separating displacement due to temperature variations was predicted and verified by the measurement results. As a result, changes in supporting r...