An automatic three-dimensional loading apparatus for static tests of truss joints

摘要

Static tests of truss joints are extremely important in investigating their mechanical behavior and collapse mechanisms. Traditional test apparatuses are especially designed to provide desired constraints and loading forces to specific joints, which leads to low testing efficiency and subsequently to high costs if tests of different joints are needed. This paper proposes a spherical three-dimensional loading apparatus which has wider universality and higher automaticity compared to the traditional ones. The apparatus consists of a hollow spherical frame, a spatial positioning mechanism, a hydraulic loading system and a control system. The loading actuators can be automatically positioned at the desired three-dimensional locations for different joints. This apparatus has been applied to test newly designed joints of the Shanghai World Expo and the Hangzhou East railway station in China successfully, and the only changes that required different tests are the repositioning of the loading actuators and applying of different forces to the joints automatically. Therefore, the proposed apparatus provides a large increase in universality over previous designs.