Журнал стальных конструкций и строительства

The structure of hybrid girder cable-stayed bridges with single pylon and single cable plane is very complex, which leads to their complicated structural behavior and adds difficulties to their construction. Few studies have been conducted to investigate the structural performance of such bridges under rotation construction. In the present study, the structural performance of a hybrid girder cable-stayed bridge with single pylon and single cable plane during rotation construction is simulated with the Midas/Civil program. The deflection and the stress of the bridge girder and the deformation of the pylon at different construction stages during the rotation construction are investigated and are checked against the bridge design code. The camber for the bridge girder is also studied. The findings from this study provide useful reference for the design of such bridges for rotation construction and the control of the bridges during rotation construction.

Steel-concrete composite systems have seen widespread use in recent decades because of the benefits achieved by merging the two materials. Due to their high stiffness and lateral load resistance, reinforced-concrete shear walls (RCSW) and steel-plate shear walls (SPSW) are considered ideal for resisting earthquake lateral loads in moderate and high-rise buildings. Recently, various schemes of composite shear walls (CSW) have been the focus of recent research. The objective of this paper is to investigate analytically the behaviour of composite shear walls as a lateral-load resisting system in comparison to RCSW. The investigation is performed on buildings with variable heights provided with either (RCSW) or (CSW). Three dimensional models for the case-study buildings are assembled using ETABS, computer software based on the Finite Element Method. The buildings are analyzed for static lateral forces computed by the Equivalent Static Load Method. Response spectra dynamic analyses, and dynamic time-history linear analyses using IZMIT earthquake record. Results are compared and interpreted so as the major findings include: First, to highlight on the structural characteristics and behaviour of composite shear walls as a seismic resistant system. Second, to compare between the structural behaviour of RCSW and CSW concerning their drifts, base shear and strength.

Hybrid girder cable-stayed bridges have been widely used around the world due to its advantages including the large-span viability of the main span with steel girder and the counterweight effect of the side span with concrete girder. The steel-concrete composite joint in hybrid girder cable-stayed bridges plays an important role in connecting the steel girder with the concrete girder and transferring the internal forces between two segments of different materials. Therefore, the performance and reliability of the composite joint is of great importance to such bridges. In order to examine the performance of the steel-concrete composite joint of a hybrid girder cable-stayed bridge with single pylon, a 1/4 scaled joint model was fabricated in the laboratory and static test was conducted. The stress distribution and the relative slip between concrete and steel under the combined action of axial force and bending moment were investigated. The test results showed that the maximum stresses of the steel and concrete components are within the allowable limits and the internal forces can be transferred smoothly between the steel girder and the concrete girder via the composite joint. The findings from this study provide useful reference and guidance for the design and testing of steel-concrete composite joints in hybrid girder cable-stayed bridges.

Fatigue failure is major concern for infrastructure due to the increasing number of steel structures reaching the end of their design life each year. Increased loadings, deterioration due to weathering, climate change and human error also negatively impact the design life. Rehabilitating steel bridge girders rather than replacing the existing structure can provide an option for an economical and sustainable future. This paper presents the results of an experimental study which implements a simple retrofitting technique to combat fatigue failure. The retrofitting technique is applied to girders which have incurred fatigue cracking within the bottom flange. Experimental tests are performed on a riveted tapered 120-year-old girder and a new prefabricated hot rolled girder. The results from the experimental tests showed that fatigue cracking within the bottom flange of girders can be easily rehabilitated to increase the girder’s capacity to that of their original design. By utilising this simple designed retrofitting technique, existing structures do not need to be replaced. The technique shown herein is a viable method for increasing the service life of steel girders providing for a sustainable future.