Study Of Fire Resistance Of The Lightweight Composite Slabs With Embedded Thin-walled Steel

The composite slabs consisting of lightweight aggregate concrete with encapsulation of thinwalled steel is a newly-designed assembled structure,the respective advantages of thin wall steel and lightweight aggregate concrete may be effectively brought into play.Compared with the ordinary floors,the composite floor is lighter and has the advantages of larger size precast,assembly construction,the least wet work,shorter construction period and being smooth of the upper and lower surface of the floor.For the main beams and secondary beams are wrapped in concrete,so the overall fire resistance and corrosion resistance of the composite floor are improved.At present,the research on the performance of the composite floor is still blank.Therefore,sudy of fire resistance of the composite slabs consisting of lightweight aggregate concrete with encapsulation of thin-walled steel has an important theoretical significance and application value.Based on experiments and finite element methods,the fire response and the post-fire mechanical behavior of 9 composite slabs consisting of lightweight aggregate concrete with encapsulation of thin-walled steel were experimentally studied and numerically analyzed,and the effect of the section parameters,loading,the form of fire,the form of cooling and the size of the floor on fire response and the post-fire mechanical behavior of the composite slabs were discussed.The results showed that the main characteristics parameters,including the steel bar,steel wire mesh,the change of cement mortar and the size of the floor,can significantly affect displacement of the composite slabs under fire and the post-fire performance of the composite slabs.The loading properties,including the distribution of loads and the change of load value,had no effect on the maximum displacement of the composite slabs under fire,but a great influence on displacemental change rule of the composite slabs under fire and post-fire behaviour of the composite slabs.The form of fire and the thickness of steel beam had no obvious effect on displacement of composite slabs under fire,but had obvious effect on mechanical properties of the post-fire behaviour of the composite slabs.It was seen that the way of spray cooling will make severe damage to the composite slabs during cooling.