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