2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference

Effect of cyclic loads on SMA-based component of cable-stayed bridge

Mr. shahin zareie, The University of British Columbia (Presenter)

The cable-stayed bridge is one of the most commons types of bridges. However, due to the lightweight and high flexibility of cable bridges, any external cyclic loading, such as traffic loads, earthquakes, and winds, may significantly affect the functionality and stability of the structure. Recent developments in materials and the construction technology, lead to enhance the integrity and performance of cable bridge under cyclic loadings. Therefore, in the last decades, the attraction to the cable-stayed bridge rises up again throughout the world.

In spite of improving the dynamic behavior and integrity of a cable bridge, their flexibility still remains a major issue of the modern cable-stayed bridge, which puts the stability at risk. Hence, the structural control systems are required to ensure the integrity and stability of the structure. Wide-ranging control systems, including passive, semi-active and active systems, are developed to install between the pier and the deck or added to the main structure.  As their weaknesses, these systems need a source of energy or are not effectively able to adjust the stability under different loading conditions.

The smart materials, particularly the shape memory alloy (SMA), are good candidates to alter with conventional materials in control systems; they increase the stability of that bridge without having disadvantages of conventional systems. SMA is a unique alloy with the ability to recover the initial shape after exposing the large deformation without requiring any source of energy. It is also able to absorb the remarkable energy of loads. Moreover, the wire (cable) is a shape suitable for cable bridge. These features make the SMA exceptional option to replace with some of the cables in the bridge to increase the integrity and enhance the performance. Therefore, SMA wires are the ideal smart element with minimum changes required in the main structures.   

In order to develop the SMA-based element, its performance should be determined under the cyclic loads, as the most common applied loads to this bridge. In this study, two important characteristics: the energy absorption capacity and the recovery ability of the SMA are investigated under cyclic loads to find the differences before and after applied cyclic loads.