EXPERIMENTAL STUDY ON THE MECHANICAL PROPERTIES OF A NEW LONG-SPAN PREFABRICATED TRUSS COMPOSITE FLOOR SYSTEM

Abstract

Horizontal load is the main controlling factor of high-rise prefabricated structure and floor system is a fundamental part that ensures the effective transmission of horizontal load in the structural system. However, the mechanical properties of traditional prefabricated systems including wooden floor and concrete floor are poor. Thus, neither of them is suitable for long-span prefabricated structures. In order to improve the mechanical properties of floor systems, a new truss composite floor composed of four factory-made floor units and assembled by bolts on site that could be applied to the long-span prefabricated structure was proposed in this study. In-plane unidirectional loading tests were performed on 4 two-story frame structural models in order to study the response of the different parameters involved in the proposed floor system. Taking the second floor of each model as the analysis object, the in-plane failure characteristics, deformation, equivalent shear stiffness were analyzed. At last, the integrality and in-plane stiffness of the new floor were also evaluated further. Test results indicate that all of the cracking loads of concrete slab in the new floor system are greater than the equivalent horizontal force of floor that is stipulated by China code in case of 7-degree rare earthquake. In addition, the reinforcement measures (e.g. pouring structural adhesives into the major slab seam and setting a post-cast stripe between floor and frame beam) can improve the mechanical properties of the new floor system greatly. The distribution pattern of cracks on concrete slab evolves from irregular local dotted distribution into significant linear distribution, which indicates that the integrality of the floor system gets strengthened greatly. More specifically, the in-plane equivalent shear stiffness of the floor is 3.4-5.3 times that of the previous one in which the reinforcement measures are not taken, at the same time, the overall lateral stiffness of the floor system is increased by 2 times, which means that the in-plane rigidity is significantly enhanced after taking the reinforcement measures. That’s to say, the floor is transformed from a semi-rigid floor to a rigid floor. Therefore, the experimental study can provide the reference for the popularization and application of the proposed prefabricated truss composite floor system. Keywords: Prefabricated composite floor, Truss composite floor system , Assembling slab seam, In-plane stiffness, Integrality of floor, Rigid floor, Semi-rigid floor