Topology Optimization For Gypsum Embedded Filler Cast-in-place Concrete Hollow Floor

Gypsum embedded filler cast-in-place concrete hollow floor, which uses precast gypsum embedded fillers as permanent formworks, is a monolithic cast-in-situ hollow concrete floor system. These floors have high social value and economic benefits. However,the waffle beamless floor,which has skilled construction technology and has been used successfully in the actual protects, is the only structure form. Therefore, the structure form of this floor is single. Besides, its structure weight is great and economic benefits are not outstanding. So, topology structures of beamless hollow roof, which have reasonable structures, excellent mechanical properties, simple construction processes, and which are based on gypsum embedded filler, are the main objective of this research.This study could increase the structure schemes for this floor system, and also provide the necessary preparations for the further research about reducing the weight and increasing the economic benefits.The topology optimization,provided by the ANSYS finite element software,for solid-slab-column structure and hidden-frame-beam girderless floor, has been made under the vertical loads. According to the topology results and engineering experiences, the hollows of solid plate can be made as follows. Firstly, the abdomen of the solid plate could be hollowed out and then the small ribs which are orthogonal could be retained. This kind of hollow girderless floor is usually called as waffle beamless roof and the distance between two ribs is not more than 1.5meters. Secondly, there still are redundant parts in the ribs of the above floor. These parts could be hollowed out and then solid ribs become hollow ribs. This kind of hollow girderless floor is named as composite open-web beamless roof. Thirdly, this kind of hollow girderless floors, which is composed of cross beams and hidden frame beams, is called as composite cross-beam and hidden-frame-beam beamless floor. The distance between two cross beams is between 2 meters and 3 meters. Fourthly, these kinds are other hollow girderless floors which are composed of hidden frame beams. Fifthly, this kind of hollow girderless floors is one of slab-column structures with prop caps. Its most important feature is that few short ribs extend from the prop caps. The above are five kinds of topology structures of gypsum embedded filler cast-in-place concrete hollow floor.Through five kinds of topology structures and existing research results, twelve structure models, which could be achieved in the actual projects, and whose volumetric void ratio is basically the same, and which are based on the gypsum embedded filler, have been designed. Three of them are T-section. They are waffle beamless floor, composite open-web beamless floor, composite cross-beam and open-web beamless floor. The rest are I-section. They are composite cross-beam and hidden-frame-beam girderless floor(this floor has two forms),composite cantilever-rib and hidden-frame-beam girderless floor, composite fore-quadrilateral-grid and hidden-frame-beam girderless floor, composite five-quadrilateral-grid and hidden-frame-beam girderless floor,composite nine-quadrilateral-grid and hidden-frame-beam girderless floor, composite hidden-prop-cap andcantilever-single-rib and slab-column-structure girderless floor, composite hidden-prop-cap and cantilever-two-ribs and slab-column-structure girderless floor, composite hidden-prop-cap and cantilever-three-ribs and slab-column-structure girderless floor.According to the static analysis under the same vertical loads by ANSYS, deflection and stress distribution of the above twelve structure models have been studied in detail.Through the static characteristic, six structure models which are the most typical and have most excellent mechanical properties have been selected. They are waffle beamless floor, composite open-web beamless floor, composite cross-beam and open-web beamless floor, composite cross-beam and hidden-frame-beam girderless floor, composite nine-quadrilateral-grid and hidden-frame-beam girderless floor, composite hidden-prop-cap and cantilever-three-ribs and slab-column-structure girderless floor. The results show that : waffle beamless floor, composite open-web beamless floor, composite cross-beam and open-web beamless floor are more suitable for conventional buildings which spans are small and whose floors under small loads because their stress distribution are uniform and simple,while composite nine-quadrilateral-grid and hidden-frame-beam girderless floor, composite hidden-prop-cap and cantilever-three-ribs and slab-column-structure girderless floor are more suitable for multilayer and tall buildings which spans are large and whose floors under big loads because of their good rigidity and small tensile stress.