【作者】 曲福来；

【导师】 黄承逵； 赵顺波；

【作者基本信息】 大连理工大学 ， 结构工程， 2008， 博士

【摘要】 近年来,异形柱框架结构在我国多层住宅结构中的应用越来越广泛。钢筋混凝土异形柱框架结构柱肢厚度与墙厚一致,避免了普通矩形柱在房间内棱角凸出的缺点,具有较好的建筑美观效果。但由于异形柱截面的不规则性,其受力性能与普通矩形柱有所差异。另外,在实际工程中经常会遇到异形柱两个柱肢长度不等的情况。不等肢异形柱的受力性能,特别是抗震性能好坏,是人们比较关心的一个问题。本文以不等肢异形柱为研究对象,主要做了以下几个方面的工作:1.对13根钢筋混凝土异形柱进行了低周反复荷载作用下正截面承载力试验研究,分析各因素(如轴压比、柱肢尺寸、配箍率及截面配筋形式等)对异形柱抗震性能的影响。结果表明:轴压比的大小对异形柱的抗震性能有较大的影响,当轴压比较小时,柱的滞回曲线较丰满,延性和耗能能力好,具有较好的抗震性能:箍筋量的增加可以有效约束受压区混凝土,提高构件的延性;当柱肢厚度不变,改变肢长时,柱的承载力提高,但变形性能有所降低;采用腹板端部加强配筋的方法来提高柱的抗震性能,效果不明显。2.采用数值积分法对异形柱构件进行了非线性分析,并编制了计算机程序。利用该程序对异形柱压弯构件的荷载-位移骨架曲线进行了模拟,通过与本文正截面承载力试验结果的比较验证了计算模型的可靠性。用该计算程序进一步分析了混凝土强度、轴压比及柱肢截面尺寸等因素对异形柱正截面承载力和变形性能的影响规律。另外,对不同荷载角作用下的不等肢L、T形柱轴压比限值进行计算,发现对不等肢L形柱,当中和轴平行截面边缘且短肢受压时轴压比最低,对不等肢T形柱,不管翼缘尺寸较大还是腹板尺寸较大,当中和轴平行翼缘且腹板受压时轴压比最低。分析了柱肢尺寸对不等肢L、T形柱的轴压比限值的影响规律,并与等肢情况相比较,给出了不等肢L、T形柱轴压比限值的工程设计参考。对箍筋约束混凝土提高轴压比进行了分析,给出了轴压比限值提高的具体数值。3.通过对12根钢筋混凝土不等肢异形柱低周反复荷载作用下抗剪性能试验研究,分析了柱肢尺寸、轴压比、水平荷载方向及配箍率等因素对异形柱承载力和抗震性能的影响。试验结果表明:翼缘柱肢尺寸增大可以提高异形柱的抗剪承载力;与等肢情况不同,单根斜向加载不等肢L形截面柱抗剪承载力不一定大于沿框架工程轴加载方向的承载力。4.采用桁架—拱模型对异形柱抗剪承载力进行了分析,通过与试验结果比较来检验该模型的适用性。结果表明,异形柱的翼缘部分参与抗剪作用,能够提高试件的抗剪承载力。结合本次试验及他人试验结果,给出了考虑翼缘影响的异形柱斜截面抗剪承载力计算公式。5.对4个钢筋混凝土不等肢异形柱框架边节点进行了抗震性能试验研究,对节点的延性、耗能能力、刚度退化等方面进行了分析。试验结果表明:异形柱框架节点的裂缝形态、破坏方式和节点抗剪承载力受柱肢长度的影响;发生梁铰破坏方式的节点,具有较好的抗震性能。6.通过对不等肢异形柱框架节点非线性有限元分析,得到轴压比、柱肢长度及柱截面形状对异形柱节点裂缝开展和应力分布的影响规律。结果表明,如果合理选择模型和参数,借助有限元程序研究异形柱框架节点的特性是有效的,可以了解不等肢异形柱形状、柱肢尺寸对节点应力的影响规律。在分析钢筋混凝土不等肢异形柱节点受力的基础上,提出了异形柱节点抗裂承载力计算公式,提出的计算公式与试验结果进行对比,吻合较好。在以上试验和理论分析的基础上,对规范矩形柱节点核心区受剪承载力进行修正,得到异形柱框架节点核心区受剪承载力设计公式。更多还原

【Abstract】 Frame structure with specially shaped RC columns has been increasing used in multi-storey dwelling buildings over recent decades in China.The thickness of specially shaped column leg is the same as a wall,so the edges of columns are invisible and the structure with specially shaped columns is beautiful in architecture.But the section of specially shaped column is irregular and its behavior is different from that of rectangular column.Sometimes,the specially shaped columns with different limb lengths may be adopted in actual engineering and the effect of limb length on mechanic behavior needed to be studied further.In this paper,the following work has been done.1.Based on the test results of 13 specially shaped columns under low reversed cyclic loading,the effects of several parameters(such as axial load ratio,limb length,stirrup ratio and arrangement of longitudinal bars,etc.) on seismic behavior are analyzed.It can be concluded that axial load ratio is one of the major factors that affect the seismic behavior.The specimen with low axial load ratio has better ductility and energy dissipation capacity for the hysteretic curve is fat.The ductility of column increases with the stirrup ratio for that the transverse reinforcements can confine the core concrete.The bearing capacity of column increases with the increase of limb length,but the deformation capacity was reduced. Increasing the longitudinal bars inthe web has little influence on seismic behavior.2.The force-displacement relationship of specially shaped column under axial compression and lateral force is calculated by numerical integral method.And a computer program is presented to simulate the skeleton curves of L,T-shaped columns.The model is proved valid by comparing the test results and calculating values,so the effects of concrete strength,axial load ratio and limb length on bearing capacity are analyzed by the computer program.Moreover,axial load ratio is calculated by numerical method for L,T-shaped columns with different limb lengths.It can be concluded that the value of axial load ratio is the minimum for L-shaped columns when the neutral axis is parallel to section edge and the shorter limb is compressed.While for T-shaped columns regardless of flange or web is larger, it is the minimum when the neutral axis is parallel to flange edge and the web limb is compressed.And some values of axial load ratio for L,T-shaped columns with different limb lengths are suggested.Also,the transverse reinforcements have effect on axial load ratio,and the values are given for reference. 3.Based on the experimental results of 12 specially shaped RC columns with different limb lengths subjected to combined action of shear and moment,a broad range of parameters that influence the shear capacity of columns were investigated.The parameters include limb length,axial load ratio,horizontal force direction and stirrup ratio.It can be concluded that the limb length can enhance the shear resistance of columns.The shear resistance of L-shaped column subjected to two directions is not always larger than that under frame direction.4.The truss-arch model is used to analyze the shear resistance of specially shaped columns.The calculated values are compared with test results and they agree well with each other.It can be concluded that the shear resistance is compressed of two parts contributed by truss model and arch model.Combining with test data of others,the formulas for shear resistance of specially shaped columns are presented by considering the flange.5.Four exterior joints with specially shaped columns which have different limb lengths are tested under low reversed cyclic loading.The ductility,energy dissipation capacity and stiffness degenerating of joints are studied systematically.Test results indicate that crack pattern,failure mode and shear resistance of joints are influenced by limb length.The joint occurring beam flexural failure has better seismic behavior.6.The nonlinear finite element models were used to analyze crack development and stress distribution of joints with specially shaped columns.The parameters include axial load ratio,limb length and section shape.And the analysis results indicate that the nonlinear finite element method is valid if the model and parameters are chosen suitably.The section shape and size have effect on crack pattern or stress distribution.On the basis of joint core’s mechanical properties,the formula of anti-crack capacity of joint with specially shaped column is proposed.The calculating results agree well with test data.According to the test and theory analysis,the specification formula is reversed to calculate the shear resistance of joint with different limb lengths.更多还原