Experimental Research On The Joint Of New Assembled Cross-beam Hollow Floor

The new assembled cross-beam hollow floor is adapted to large space floor system.As one of the assembled floor,it also has advantages of high degree of pre-manufacturing,less wet operation,fast construction,short duration,economical and green.With lightweight foam concrete block replacing the concrete near the neutral axis,it also makes the floor thermal-insulated,light weight and large span,and these are unique advantages.But the new floor has joints,as the weak part of the system,they decrease the mechanical properties of the floor,including bearing capacity,stiffness and dynamic characteristics,so it is necessary and significant to do experimental study and theoretical analysis about joints of the new floor.The static load test of the new floor was carried out.Vertical static load was applied on the floor model with different joints,the results of flexural deformation,cracking load,stiffness change of the test floor and the stress or strain of each component were obtained.From the results,all models were bending failure and their mechanical properties were different due to different structure of joints.When 2 joints were not set in the middle,the floor' bearing capacity,cracking load,stiffness and other mechanical properties were closer to the floor which was overall casting.When 1 joint was arranged in the middle,floors' mechanical properties had weakened greatly.Besides,increasing roughness of the bonding surface between the old and new concrete and joint' width also improved floors'mechanical properties to some extent.Consequently,the location of joints was main factor to effect new floor' property,and joints should be arranged in someplace where internal force was smaller.The finite element analysis software ABAQUS was also used to simulate the test of the new floor,the results of simulation matched with testing results.In the elastic phase,both of them were coincide,the deviation appeared in elastic-plastic stage,but the integral development trend was same.So the method of the finite element analysis was reasonable and reliable.Combined with results of the test and finite element analysis,design recommendations for the new floor' joint were proposed,which were on the terms of increasing joints' width,concrete bonding and arrangements for the number and location of joints,then these suggestions will be applied to engineering.The new floor's internal force analysis method can be equivalent to the principle of solid plate,that is,according to the vertical bending stiffness of the new floor equivalent of a solid plate,and using the same internal force analytical method of ordinary solid plate.A new setting method of joints is put forward to applied to new assembled cross-beam hollow floor whose span is approximately 10m,it is called Anti-symmetric distribution.Combined with design recommendations,finite element analysis about the new floor with Anti-symmetric joints is carried out.When joints are set in floor by the new method,the floor's mechanical properties are much closer to the floor which is overall casting than the floor whose joints are set in 1/3 of floor.So Anti-symmetric distribution is more suitable for new assembled cross-beam hollow floor.