Theoretical And Experimental Research On The Waffle Hollow-core Composited Floor

Waffle hollow-core composited floor, composed of cast-in-place beams and prefabricated concrete box fillers, has the advantages of large span, lightness, convenience in construction, various adaptation and lower cost,suitable to the large column span and bay width floor structure. Waffle hollow-core composited floor is being applied in engineering practice more and more. However, up to now, the research on waffle hollow-core composited floor is rather limited home and abroad. In this paper some structural properties of this kind floor system were studied by the experimental research and theoretical analysis. At the same time, according to the structure performance characteristic, it also provides practical and concise computational method for engineering application. The main contents are as follows:1. The waffle hollow-core composited floor's working performance under vertical load has been studied by static destructive testing of two hollow floor's components and a ribbed component. The test results proved that both roof and wall of the prefabricated concrete box fillers were in good bond with cast-in-place concrete dense rib. The ledger wall also has obvious contribution to the floor's stiffness. Joint parts of ribbed beam is the structure's weak point,special attention should be paid when design. In all, waffle hollow-core composited floor is similar to ribbed floor in the structure performance characteristic.2. A finite element model of a 9m×9m waffle hollow-core composited floor was established by the software-ANSYS to analyze the behavior of rib and boards with the simple support and the fixed support, respectively. At the same time, analysis on both waffle floor and solid floor which are in the same condition is also done to compare with the former one, supplying a certain theory gist for such floor system's design and calculation.3. According to principle of the equivalent flexural rigidity,waffle hollow-core composited floor was analogized to solid two-way slab,then the analytical solution of the slab's internal force and deflection was proposed based on the theory of elastic thin rectangular plate. In order to make the calculation convenient, both deformation and internal force of the waffle hollow-core composited floor can be calculated by using tables' coefficient of two-way solid slab, which has been modified. When concrete cracking, flexural rigidity will reduces,then tables'coefficient was modified accordingly. Compared with the ANSYS results, it found the modified coefficient is feasible.4. The method for calculating bearing capacity of waffle hollow-core composited floor has been researched in the paper. Yield-Line method according to Johansen's yield theory can be adopted to calculate bearing capacity of waffle hollow-core composited floor. Because of dome effect caused by lateral supports, the test value of bearing capacity of hollow floor was remarkable higher than the value of calculation. A preliminary analysis has also been done to study the factors influencing dome effect in this paper.