Investigation Of Cable-Stayed Roof Structure For Low-Rise Stadium Bleachers

Abstract

The cable-stayed roof is structural technology that evolved from cable-stayed bridge construction in which cables are used to replace intermediate columns. Cable-stayed roofs are preferred over the other because of their lighter weight, effectively covering a wide space area and minimum time needed for construction. This paper presents an investigation of the cable-stayed roof structure for low-rise stadium bleachers. The main objective of this study is to study factors that affect the response and design of cable-stayed roofs for low-rise stadium bleachers. The research used multistage sampling method to generate its samples. Study of cable usage and a geometrical study were each conducted separately for the cable-stayed roofs. The geometrical study focused on achieving the best arrangements of the roof structure by changing the bay spacing and roof angle. Then a study of cable usage was conducted by evaluating various values of initial tension in cables and the number of cables used per truss. In both steps, the parameters used for comparison were: horizontal and vertical displacements of roof, bending moment of in pylons, final tension in the cables and the total weight of the roof structures. The design and analysis of the structures were performed using SAP2000 V24. The results of the geometrical study revealed that all the roof displacement, bending moment in pylons, the final tension in cables and weight of structure increased as the roof slope increased from 2.5°to 5°and 7.5° and as bay spacing increased from 3m to 4m and 6m. As a result, the cable stayed roof with a 2.5° slope and 3m bay spacing was selected to have the best structural geometry. However, in the study of cable usage, all the roof displacement, bending moment in pylons, the final tension in cables and weight of structure decreased as initial tension in cables increased from 2% to 60% of cable breaking force and as the number of cables increased from 1 cable per truss to 2 and 3 cables per truss. Due to these, the cable-stayed roof with 3 cables per truss and 60% of cable breaking force as its initial tension was chosen for an effective cable arrangement. This study also shows that using the proper cable arrangement on the roof with the best geometry improved the response of the cable-stayed roof to the wind load by minimizing the values of horizontal roof displacement, vertical roof displacement, bending moment in pylons, the final tension in cables and weight of structure by 33.5%, 13%, 29%, 24.7%, and 26.6%, respectively.