The widely used orthotropic steel deck system is subject to several durability problems: fatigue cracking of the steel, wearing of the surfacing, and corrosion. Thus, the composite deck system composed of an orthotropic steel deck and an ultrathin reactive-powder concrete (RPC) layer was proposed. In a prefabricated composite deck system, joints formed between the prefabricated RPC layer and the cast-in-situ RPC layer are defined as wet joints. The experimental study was conducted on the tensile behavior of RPC wet joints to ensure the integrity of the prefabricated deck system and the serviceability and durability of the RPC layer. Two series of tests were conducted, including seven tensile tests on panels and four negative bending tests on beams. In these tests, five types of new wet joint details were designed in addition to the integral casting detail and the conventional wet joint with a vertical, plane interface. To study the mechanical properties and crack resistance performance of differen...

The steel–concrete–steel (SCS) sandwich composite structures with orthogonal longitudinal and transverse (bidirectional) steel webs exhibit superiorities in strength, ductility, impact resistance, blast resistance, and construction efficiency compared with the traditional engineering structures, offering a competitive alternative for applications such as submarine tunnels, nuclear shells, protective structures, offshore structures, etc. While there were several practices in engineering, the current design method is an application of the concrete code and there are few experiments that could support the design theory especially for the shear resistance. Unlike RC beams or steel beams, the SCS composite structures with bidirectional steel webs have multiple shear force transferring mechanisms, and it is of importance to investigate the contributions of the different mechanisms and how they work together as a composite structure. To address this problem, 16 shear tests of SCS composite structures with bidirectional steel webs were carried out and theoretical analysis was conducted. The shear resistance is categorized into three mechanisms: the composite truss, the pure shear of the axial web, and the dowel action of the flange. Then the theoretical method to predict the shear resistance considering the coworking of different mechanisms is proposed and compared with existing methods. It is proved that the proposed method reveals the antishear mechanism and is of satisfactory accuracy.

This paper presents an experimental program designed to examine the long-term behavior of composite steel-concrete beams under sustained loads. The test program consisted of two simply supported beams under positive bending moments and two cantilever beams under negative bending moments. Long-term deflections, strains, and the cracking behaviors of the specimen beams were monitored over a period of 3 years. The primary observations are: (1) the deflection of the simply supported beam under positive bending moment increased quite significantly over the time due to creep and shrinkage, with the midspan deflections after 3 years of loading reached 2.5 times of the initial deflections, and (2) the cracking of concrete occurred in hogging moment regions for cantilever beams due to the combined effects of concrete shrinkage and sustained negative bending moments. Current design codes were evaluated through a comparison between the calculations and testing results. It was found that the effective modulus method ...

Because a large longitudinal force exists in hybrid girder cable-stayed bridges due to the cable tension, its transfer mechanisms on the steel-concrete combination segment would be an important issue. In this study, experiments and theoretical analysis were conducted to characterize the longitudinal force transfer mechanisms of the steel-concrete combination segment in hybrid girder cable-stayed bridges. Five full-scale local structure specimens were designed and manufactured based on the original design of the steel-to-concrete transition zone according to a completed cable-stayed bridge in China. The specimens were subjected to monotonic loading and tested up to complete failure. The load-slip curves; stress distribution and failure modes, which varied with the thickness of the bearing plate; and the shear connector distribution were obtained. To simulate the test properly, calculation methods for predicting the shear connector capacity and corresponding load-slip curves were proposed based on t...

Steel plate reinforced concrete (SPRC) composite shear walls, which are composed of steel columns embedded in boundary elements and an embedded steel plate in the wall web, have been used in super-high-rise buildings. When subjected to rare earthquake loads, combined tension-bending-shear actions are often generated in the shear walls of super-high-rise buildings because of the increasing demand for a greater height–width ratio. Based on quasistatic tests on seven SPRC shear walls under tension-bending loads, the seismic behavior of SPRC shear walls with various steel-content ratios and axial tension ratios was investigated. The failure mode, strength and displacement capacity, stiffness degradation, shear deformation, damping coefficient, strain, and cracking of each test specimen are presented in detail. The failure mode is divided into tension-bending failure, anchorage failure, and torsional buckling failure according to the test results. The strength, stiffness, and ductility of the SPRC shear walls were significantly reduced with an increase in the axial tension ratio. The fiber beam-column finite-element (FE) model was simulated using MSC.MARC software. A comparison showed that the FE model predicted the load-displacement relationship, stiffness degradation, and ultimate capacity with a reasonable level of accuracy. Based on the test results, a design method is proposed for predicting the ultimate strength of the SPRC shear walls under tension-bending combined loads, and recommendations for improved anchorage design are proposed.

The creep, shrinkage, and cracking of concrete may induce time-dependent changes in the stresses, internal forces, and deflections of steel-concrete composite beams. This paper presents an analytical model to consider these effects in analyzing the long-term behavior of composite beams under service loads using the step-by-step procedure. Under negative moments, the model accounts for the cracking, stress relaxing, tension stiffening, creep, and shrinkage of concrete. Meanwhile, a method is proposed to calculate the maximum crack width of the concrete slab by considering the shrinkage and creep effects. Four composite beams continuously loaded for about 3 years were analyzed using the proposed model. A good agreement is observed between the experimental results and the calculations by the proposed model. A discussion is also made about the aging coefficients in the age-adjusted effective modulus method under different loading conditions.