Flexural Stiffness And Bending Capacity Of Simply-supported Composite Slim Beam With Deep Deck

The steel-concrete composite slim beams, with the steel beam encased inconcrete floor slabs, have the advantage of steel and concrete workingtogether by using the bond force between them, and in this way themechanical properties of the two material are efficiently developed. This newtype of composite beam has many advantages, such as low structural height,fast erection, efficient fire resistance and good serviceability, etc. Therefore,there is a promising application prospect in multi-storey steel buildings,especially in residential buildings.Currently, the composite slim beam with deep deck is much more popularin buildings than the other type of the beam, but researches on the flexuralstiffness and loading capacity of the beam are not adequate, as it is neededconsidering influence of such factors as the variable sections, development ofcracks, nonlinear characteristic of material, and so on. In Finland, UK,Sweden and other countries, some related design codes about simplysupported beams are proposed, but these codes depend mainly on experienceand need further demonstration. Moreover, less research has been carried outin China either experimentally or theoretically.In this thesis, the structural behavior of a simply supported compositeslim floor has been investigated by finite element method (FEM), whichindicates the effective width of the middle beam is no less than one quarter ofthe beam span in elastic stage. Then, two simply supported beams, withconcrete slab width about 1/8 span, have been designed and tested in order tostudy the flexural behavior of the beam, and FEM has also been used toanalyze the stress/strain distribution of sections additionally, which indicatesthat the sections of the specimens remain flat during the elastic stage and steelsections at mid span almost fully yield in limit stage condition. So, theclassical material mechanics theory could be used to analyze the flexuralstiffness of sections and average stiffness of the simply-supported beam. Aformula is derived to calculate the flexural stiffness of composite slim beamwith deep deck. The equivalent rectangular stress distribution is suggested tobe used in the calculation of the bending resistance, and related formulae havebeen derived corresponding to three common location of the plastic neutralaxis of sections.In this thesis, all specimens constitute of domestic materials intently,which aims at reducing the cost of future application for this new type ofcomposite beam in China. The effectiveness of the bond force between steeland concrete has been investigated, and accordingly, some constructiondetails suggested.