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జర్నల్ ఆఫ్ స్టీల్ స్ట్రక్చర్స్ & కన్స్ట్రక్షన్

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వాల్యూమ్ 4, సమస్య 1 (2018)

సమీక్షా వ్యాసం

Seismic Performance Improvement of Steel Moment Resisting Frame Using Shape Memory Alloy

Bajoria KM and Jadhav RV

Shape Memory Alloys have a wide range of applications due to their special properties. The properties like shape memory effect, super elasticity (SE) and high damping are useful to enhance structural behavior and seismic resistance. In this paper, super elasticity effect of two different alloys NiTi and Fe based SMA is used to enhance the structural properties of a steel Moment Resisting Frame and comparison of response of frame with connection of two different alloys is studied. The finite element analysis of moment resisting frames is done using Ansys-15. The geometry and loading conditions of frames are taken from previous research. For the comparison of structural behavior of the steel frame with Shape Memory Alloy at beam column connection are checked for lateral loading. Also, the response of the frame is checked for time history analysis using past earthquake data. Comparison of the time history analysis response of bare frame (Steel only connections) and frame with SMA at connection suggested excellent performance of frame equipped with SMA. The main aim of the study is reducing residual displacement of steel frames after earthquake loading. To check the performance of the frame for loading unloading cycle, incremental lateral loading is applied to the frame up to maximum load and then it is unloaded completely. The SMA equipped frame shows almost 85% recovery of the residual displacement. The reduction in residual displacement of the SMA equipped frame is also seen in case of time history analysis. Though Ni-Ti SMAs show a little more recovery in residual displacement, cost comparison shows using Fe based SMA in Civil Engineering industry will be beneficial for the maximum utilization of material with lesser cost.
పరిశోధన వ్యాసం

Structural Performance of a Hybrid Girder Cable-Stayed Bridge during Rotation Construction

Deng L

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.

సమీక్షా వ్యాసం

Composite Shear Walls an Efficient Seismic Resistant System for Multi-Story Buildings

Reslan N, Masri A and Machaka M

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.

పరిశోధన వ్యాసం

Experimental Study on the Steel-Concrete Composite Girder Joint of a Single Pylon Cable-Stayed Bridge

Deng L

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.

పరిశోధన వ్యాసం

Experimental Investigation of Retrofitting Techniques for Steel Bridge Girders Subject to Fatigue Failure

Mirza O, Milner L, Mashiri F

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.

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