预应力型钢混凝土框架试验研究和设计理论

基于两榀预应力型钢混凝土框架的竖向静力试验,对其破坏形态、裂缝的开展与分布、刚度变化、弯矩调幅等特征进行研究.试验结果表明:预应力型钢混凝土框架梁发生类似于钢筋混凝土适筋梁的正截面受弯破坏,属延性破坏,框架梁端形成塑性铰实现了塑性内力重分布,位移延性比大于3,弯矩调幅值为30%左右,弯矩调幅值高于普通预应力混凝土结构.最后分析了次内力产生的本质,提出考虑次内力包括次弯矩、次轴力的预应力型钢混凝土结构的抗弯极限承载力、抗裂度、刚度及最大裂缝宽度计算公式,计算结果与试验数据较吻合.本文计算理论反映了现代预应力设计理论的新思想,为《预应力混凝土结构设计规范》的编制提供依据.

Experimental Investigation and Design Theories on Prestressed Steel Reinforced Concrete Frame

Based on the vertical static test of two prestressed steel reinforced concrete frames,their characters,including failure pattern,crack development,rigidity change and moment redistribution,were investigated.The test results have shown that prestressed steel reinforced concrete frame beams,similar to under-reinforced concrete beams,are ductile failure;plastic hinges appear and plastic redistribution of internal forces is achieved on the frame beam end;and the ductility ratio of displacement is greater than 3.Moment redistribution values are about 30%,which is higher than ordinary prestressed concrete structures.The generation nature of secondary forces was analyzed and the calculation formula of ultimate flexural load-carrying capacity,crack resistance,stiffness and maximum crack width were presented,which consider secondary internal forces,including secondary moment and secondary axial force.The calculation results agree well with the test values.The calculation theory in this paper reflects new ideas of modern prestressed design and can provide reference for the establishment of "Prestressed Concrete Structure Design Code".