Advanced Materials Research Vols. 255-260

Abstract: The cracking control standard of water delivery structure is quite strict especially for middle-route of south-to-north water transfer project with long distance water transfer, large discharge, the crack prevention standard is extraordinary strict and must be reached. Early crack during construction period will affect safe operation of aqueduct, and diurnal variation of air temperature has significant effect on temperature field of thin-walled structure. Construction process simulation and temperature filed calculation during construction period about Caohe river landing rectangle aqueduct of Beijing-Shijiazhuang emergency water supply engineering of middle-route of south-to-north water transfer project are carried out by FEM , and compared with the monitoring temperature. The comparison result shows that temperature field during construction can be accurately simulated by calculation, which is helpful for guiding construction and choosing construction scheme, and worthy to popularize to other similar projects. From the calculation and monitoring, the maximum temperature difference is less than the standard, so there will be no serous cracks during construction in Caohe river aqueduct.

Abstract: Analysis of steel surface interfacial bond stress-relative slip constitutive relationship in simply supported steel reinforced concrete (SRC) beams tensile region and compressive zone, a simplified calculation model is presented. The interface slip and the effect of the slip on the deformation of steel reinforced concrete beam under uniformly distributed loads are studied. Using elastic deformation theory, a set of analytical expressions for interfacial slip and deformation of simply supported SRC beams are obtained. These expressions can not only describe the interface slip distribution, but also account for its effect on the deformation. The present theoretical analysis bench-mark finite element analysis of load bearing capacity and deformation of SRC beams.

Abstract: This paper studies the parameter effect of side retainers on seismic response of bridges with flexible rubber bearings. The pounding effect between girder and side retainers is analyzed by the nonlinear time-history analysis. The pounding and sliding of bearings are simulated by the nonlinear contact elements. Comparative analysis of seismic performance of bridge with/without retainers is carried out. Furthermore, the seismic performances of ordinary retainers and new retainers are compared. Finally, the effect of side retainer parameters on seismic response of bridge is analyzed. The results indicate that the sliding of elastomeric pad bearing should be considered in seismic design. It is shown that the retainers can effectively restrain the relative displacement between girder and piers, and the new type of retainers can greatly reduce the pounding force. It is also proved that both stiffness and gap of the retainer have significant influences on the pounding force.

Abstract: In this paper, the vehicle-bridge transverse vibration mechanism was analyzed; the vehicle-bridge vibration model was built and the transverse reinforcement schemes of open steel plate bridges were designed. Numbers of analysis were carried out for the transverse vibration of 40m deck steel plate bridges before and after reinforced, under input of random artificial hunting waves and track irregularity. The results show that when the hunting wavelength is 8.5m and the velocity of the train is around 50.4~75.6, the transverse amplitudes decrease differently after reinforcement. The effectiveness of various reinforcement types is evaluated by using the computer simulation programs.

Abstract: The analysis and mechanism of excessive long-term deflection of long-span prestressed concrete (PC) box girder bridges is concentrated recently. However, because of the lack of computing method, three dimensional (3D) analysis of PC continuous bridge especially including long-term shear lag effect is hard to analyze. According to this, a 3D creep analysis method for long-span PC bridges is illustrated in this paper first. The shear lag analysis of loads, prestress and their combination effect is carried out respectively. Based on this, the effect of shear lag to the long-term deflection of mid-span and whole-shape of the bridge is demonstrated. At the end, the different of computing between analysis with or without considering shear lag is discussed and some suggestion is proposed.

Abstract: Steel-concrete composite structure has been applied in bridge tower in recent years. In order to investigate the influence of different cross sections on the mechanical behaviors of composite bridge tower, two composite tower models with different cross sections, including rectangle and rectangle with chamfers, were designed and tested under axial compression. Through analysis of the local buckling modes and axial strain of the panels between the two models, it shows that in composite towers, compared with rectangle section, the section of rectangle with chamfers is more favorable in improving the capability of the tower to resist local buckling. For the panels in the chamfer have the smallest width-thickness ratio, so they can supply more advantageous support to their adjacent panels which are not in the chamfer and with the larger width-thickness ratio.

Abstract: In the past ten years, considerable increases in traffic volume and vehicle loads have caused obviously fatigue damage in existing highway reinforced concrete bridges in China. Some highway reinforced concrete bridges were damaged seriously, leading to the whole bridge collapse sometimes because of overloading and oversize trucks. In order to observe the highway load character in Shaanxi province, truck weigh device is set up in highway pavement to measure axle weights and axle spacing. Based on these data, it can be classified and generalized the different classes of vehicles, and drawn out the simplifying fatigue truck model in Shaanxi province. Furthermore, the fatigue truck model was used to evaluate the fatigue life and service safety of typical concrete bridges.

Abstract: Steel-concrete composite bridge towers have the advantages of steel and concrete, they have a good prospect in bridge engineering. However, the applications and related researches of composite bridge towers in China are rare. Therefore, in this article, two types of steel-high performance concrete composite bridge tower and pier models, which had none and one row of longitudinal stud connectors, were designed. The axial compression tests were practiced on the two specimens, in order to study the influence of connectors on the mechanical properties of the composite bridge towers and piers. From the tests, the ultimate bearing capacity and failure mode were obtained, and the regularities of strains and deformations were also analyzed. The results show that setting up stud connectors on the composite towers and piers can improve the ductility and the ultimate bearing capacity obviously.

Abstract: A new steel-concrete composite girder which is an I-shaped girder with concrete-filled rectangular tubular flange was proposed in this paper. The web depth of the new composite girder is reduced, and lateral torsion buckling stiffness is improved, which can increase the buckling capacity of the girder. In order to study the bending capacity of concrete-filled rectangular tubular flange composite girders (CFRTFCG), the static tests of CFRTFCG with flat and corrugated webs under concentrate lateral loads had been performed. Based on the test results, the bending limit load capacity and mechanical behavior of the specimens were obtained, the bending failure mechanisms of CFRTFCG were also summarized.

Abstract: This paper evaluates the shear resistance of hybrid I-beams fabricated by high performance steel and conventional steel. A number of hybrid I-beams are modeled and analyzed to determine their shear failure mechanism characteristics, considering parameters of web slenderness (hw/tw), frame action from end-stiffeners, ratio of flange width to web depth (bf/hw) and panel numbers. The analyses conclude that, in shear resistance calculation, plate beam with inter and slender webs often fail in inelastic or elastic shear buckling while ultimate shear resistance of compact webs is given by the shear strength of the material. What’s more, more rigid stiffeners provide more fixity to flange plates and increase the post-buckling resistance of plate beam. For plate beam with several panels, the shear stress at the ultimate load is similar. Finally, the I-beams with larger flange width to web depth ratio would develop larger shear strengths and then shear deformation cause formation of plastic hinges.