U-section steel sheet piles are widely used as support structures in bridge foundation pit excavation. Because of the reduced modulus action (RMA) effect of U-section steel sheet piles, it is difficult to balance structural safety and construction cost in engineering. In this paper, a case study of a foundation pit supported by U-section steel sheet piles in the middle and lower reaches of the Yangtze River was carried out. A three-dimensional FEM of the support structure was established and the RMA parameter analysis was conducted. According to the measured data, the RMA value was identified. Based on the RMA value, the support structure of the subsequent foundation pit was optimized and the deformation of the pile head was monitored during the excavation process. The measured deformation was in good agreement with the predicted value, verifying the feasibility of the inferred RMA value. Finally, to solve the uncertainty problem of the U-section steel sheet pile RMA in general situations, an optimization strategy for the design of the U-section steel sheet pile support structure was proposed.

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...

Push‐out tests were widely used to determine the shear bearing capacity and shear stiffness of shear connectors in steel‐concrete composite structures. The finite element method was one efficient alternative to push‐out testing. This paper focused on a simulation analysis of the interface between concrete slabs and steel girder flanges as well as the interface of the shear connectors and the surrounding concrete. A cohesive zone model was used to simulate the tangential sliding and normal separation of the interfaces. Then, a zero‐thickness cohesive element was implemented via the user‐defined element subroutine UEL in the software ABAQUS, and a multiple broken line mode was used to define the constitutive relations of the cohesive zone. A three‐dimensional numerical analysis model was established for push‐out testing to analyze the load‐displacement curves of the push‐out test process, interface relative displacement, and interface stress distribution. This method was found to accurately calculate the shear capacity and shear stiffness of shear connectors. The numerical results showed that the multiple broken lines mode cohesive zone model could describe the nonlinear mechanical behavior of the interface between steel and concrete and that a discontinuous deformation numerical simulation could be implemented.

To fulfill the navigation development plan of the Hu-Jia-Shen Channel located on the eastern coast of China, it is necessary to upgrade its width and clearance height. The Qifeng Bridge, an arch bridge over the channel, is required to be raised by 2.5 m using the integral lifting method. In this paper, the operation principles of the hydraulic jack system, the composition of the supporting structures, and the lifting process of the bridge are presented. To verify the proposed procedures adopted in this project, a 3-dimensional finite-element method (FEM) model, incorporating a bridge-capping beam of main span and a supporting girder, is established to analyze the contact behavior and stress distribution characteristics between the beam and supporting girder. The induced stresses in the superstructure and supporting structures are also monitored and analyzed.

The coupled effect of loading rate and temperature on the compressive behaviour of cement asphalt mortar (CA mortar) is investigated in this paper. The uniaxial compressive test is conducted with CA mortar subjected to three different temperatures from 5°C to 35°C and seven different loading rates in the range of 1–50 mm/min. The failure modes, experimental stress–strain relationship and compressive strength of CA mortar are obtained in this study. Based on the experimental results, it is found that CA mortar fails in a similar manner with varying temperature, while the higher loading rate leads to a more severe and quick failure of CA mortar. The shape of the stress–strain curve of CA mortar is shown to be similar at different temperatures and loading rates, but the compressive strength and peak strain varies with temperature and loading rate. According to the experimental results, the compressive strength increases with decreasing temperature and increasing loading rate up to 20 mm/min. An empirical equation to determine the compressive strength of CA mortar with respect to temperature and loading rate is proposed and verified by the experimental data.