Reduced Stiffness Of Composite Beams Considering Slip And Shear Deformation Of Steel And Effective Breadth Of Slab With Crack In Hogging Moment

The steel section in a steel-concrete composite beam is small compared with a pure steel beam.And in a composite beam,only the web of the steel beam is counted on to resist shear.Thus the shear stress and the deformation in the web of I-steel section are much larger than those in pure steel beams under the same loads,which could have a non-ignorable effect on the deflection.In this paper,a theory is developed for analysis of steel-concrete composite beams with interfacial slip and shear deformation in steel considered.The main research work covered in this paper includes:(1)Closed-form solutions are derived for simply supported composite beam under uniform and mid-span concentrated load respectively.(2)Closed-form solutions are derived for composite beam without slip.They provide simple formula to calculate shear deflection.And rough equivalent bending stiffness is found;(3)Examples are given to compute various quantities of beams.Comparing the calculated results with those by ANSYS as well as Dai's test results,good agreements are found;(4)A precise formula for the equivalent bending stiffness of the composite beams is found by which the deflections of the composite beams can be calculated as if they were common Bernoulli beams.Another theory is derived for the effective breadth of concrete slab with crack in hogging moment,including:(1)Two close-form solutions are derived for concrete slabs which are entirely cracked as well as partially cracked in hogging moment.(2)Solutions are proposed to calculate a reduction factor to obtain the effective breadth.