超高性能混凝土-充填式窄幅钢箱组合梁刚度计算
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中图分类号：U448.38 文献标志码：A
Abstract：Toresearch mechanical properties of ultra-highperformance concrete-filld narrow steelbox composite beams under negative bending moments，reverse static loading tests were conducted on six test beams taking volume fraction of steelfiber inultra-high performance concrete，thicknessof ultra-high performanceconcretelayerin flange，and heightof flled normalconcrete innarowstel boxbeams asvariables.Action mechanismoffillednormal concrete wasanalyzed by using ABAQUS software.An analytical formula for deflection curve of composite beams was derived considering slip efct，anda simplifiedreduction stiffesscoefficient wasproposed.Theresults showthatfailure modesof thecomposite beams are bending failure.There is slip effect between theflange and thenarow steel box girder，andbothof them conform to plane section assumption.Comparedwith normalconcrete flanges，introducing ultra-high performanceconcrete layerintotheflanges canreduce main through cracks.Diferent volume fractionsof steelfiberinultra-high performance concrete increase cracking load of composite beams by 74.7% to 231.5% ，and post-cracking stiffness by 10.75% to 19.9% ： Thefilled normal concretecan effctively prevent local buckling of thenarrowsteelbox girderatloading points，and efctive compression height of the filled normal concrete is1/5 to1/7of web plate height.Considering impactsof slip efctand flange crackingon stifnessofcomposite beams，when the proposed simplified reduction stfnesscoefficientis adopted and mid-span deflection of composite beams is calculated in segments with a bilinear form，theaverage error between the calculated value and the test value of mid-span deflection under yield load is 5.85% . When flange cracking is ignoredandonlyslipeffectisconsidered，theaverageerorbetweenthecalculatedvalueandthetestvalueofmid-span deflection is 11.92% ：
Keywords：composite beam； stiffness；reverse static loading test；ultra-high performance concrete；slip effect
钢-混凝土组合梁具有自重轻、力学性能好、经济效益高等优点，广泛应用于桥梁、建筑等工程，但是组合梁在负弯矩的作用下，存在翼板受拉易开裂、钢梁受压易局部失稳等问题，对组合梁的刚度及耐久性等产生不利影响[]。（剩余13211字）
