Thermo-Mechanical Analysis Of Assembly Steel-Truss Waffle Slabs

In order to adapt to the industrial development trend of building industrialization and housing industrialization,A new type of assembly steel-truss waffle slabs has been introduced,in this kind of slab,foam blocks is filling with ribbed beams and the steel frames is truss structure,it is necessary to study its structural and heat behavior for a wide applicaton.An experimental investigation and numerical analysis for this kind of waffle slab has been carried out.A strength prediction method has been recommended.According to the experimental results,because of weakening effects of the bolt hole for the connection between steel trusses in two-way slab specimen,insufficient local bearing capacity of two-way slab led to punching failure,the crack pattern of ribbed beams is flexure-controlled and the applied load has been transferred along tow directions of slab;for one-way slab specimen,8 concrete block was put on the surface of slab to simulate the uniform load distribution,and there is no punching shear failure is seen,the final failure happened in the short ribbed beam,the final failure is also looked as a flexture one,load transfering model is one-way type along the short span ribbed beams;when two different type of floor damaged,the maximum deflection deformation are more than 50 mm;In the whole loading process,the entire foam blocks did not fall from slabs,it shows that bonding performance between foam pieces and ribbed beams is pretty well.The temperature field characteristic of the new type of steel-truss ribbed floor under ISO834 temperature curve was analyzed by ABAQUS finite element simulation.Simulation results show: because excellent heat insulation performance of foam pieces,while fire effected on the bottom of the plate,top surface temperature kept at room temperature,and along the vertical and horizontal section of the floors between ribbed beam and foam blocks,temperature gradient changed obviously.The ultimate bearing capacity of two different kind of slabs was determined by static performance simulation under different boundary conditions.Through the thermal-mechanical coupling simulation,when distributed load is 3 kN/m2,some steels in several middle sections of short span and edge support have been yielded at that time of temperature under 2 hours' effect of ISO834 temperature curve.Due to the thin reinforcement protection layer,the steel temperature is so high under high temperature,the bearing capacity declined sharply.Several practical calculation methods about the design theory of ribbed floor was recommended,By contrast,results shows that solving results of pseudo-plate method based on elastic mechanics algorithm anastomoses closely with simulation value.Flange enhancement effectes is not considered in other practical calculation methodes,so internal force calculation results is larger.Through the above research,the mechanical performance characteristics of the ribbed floor was obtained.Valuable reference for the design and construction of ribbed floor was able to provide by this research.