基于梁铰机制的柱端弯矩增强措施研究

发布时间：2018-04-09 18:17

本文选题：钢筋混凝土　切入点：框架结构　出处：《土木工程学报》2014年04期

【摘要】：汶川地震中钢筋混凝土框架结构塑性铰普遍出现在柱端,该震害现象促使我国抗震规范在2010版提高了"强柱弱梁"措施。新的柱端弯矩增大系数取值对一、二抗震等级而言与已有研究结果相近,但低烈度区、三级抗震的取值仍缺乏依据。该文按现行中国规范设计5个位于Ⅱ类场地的不同设防烈度分区、不同抗震等级的规则钢筋混凝土平面框架,讨论现浇板钢筋、梁下部纵筋等对"强柱弱梁"措施的影响规律。以强震下除底层柱下端外其他柱截面纵筋不屈服的梁铰机制为原则建立非线性计算模型,对每个框架分别输入30条符合要求的地震波,在OpenSees平台上对5个框架进行罕遇地震下的非线性反应分析,并对柱端弯矩增大系数需求进行统计分析。结果表明,对于7度区三级抗震框架的柱端弯矩增大系数,抗震规范取1.3明显不足,建议提高其取值,并同时附加将中间节点处绝对值较小的梁端负弯矩取为零的计算原则;8度区二级框架、9度区一级框架的柱端弯矩增大系数需求的统计结果较规范取值偏大得相对较少。基于梁端实际配筋和材料强度标准值的柱端弯矩增大系数需求的统计特征值离散性更小、沿楼层变化不大,同时其已包含板钢筋的贡献,是相对更好的"强柱弱梁"措施形式,此时抗震规范的一、二抗震等级的弯矩增大系数仍有待提高。
[Abstract]:In Wenchuan earthquake, plastic hinge of reinforced concrete frame structure is commonly found at the end of column. The earthquake damage phenomenon causes the seismic code of our country to improve the measure of "strong column and weak beam" in 2010 edition.The new value of the increasing coefficient of moment at the end of column is similar to the results of the previous studies for the first and second seismic grades, but the value of the three-stage earthquake resistance in the low intensity region is still lack of basis.In this paper, five regular reinforced concrete plane frames with different fortification intensity and different earthquake resistance grade are designed according to the current Chinese codes. The influences of cast-in-place slab reinforcement and longitudinal reinforcement on the measures of "strong column and weak beam" are discussed.Based on the beam hinge mechanism of column section without yielding under strong earthquake except for the bottom column, the nonlinear calculation model is established, and 30 seismic waves are input to each frame separately.The nonlinear response analysis of five frames under rare earthquake is carried out on the OpenSees platform, and the demand for increasing coefficient of bending moment at the end of column is analyzed statistically.The results show that the seismic code is obviously insufficient to increase the coefficient of bending moment at the column end of the three-level seismic frame in the 7 degree region. It is suggested that the value of the code should be improved.At the same time, the calculation principle of the negative moment at the end of the beam with small absolute value at the intermediate node is taken to be zero. The statistical results of increasing coefficient of column moment in the second grade frame in the range of 8 degrees and in the zone of 9 degrees are relatively small compared with the standard values.Based on the actual reinforcement at the end of the beam and the standard value of the material strength, the statistical eigenvalue of the increasing coefficient of the moment at the end of the column is less discrete and has little change along the floor. At the same time, it already includes the contribution of the steel bar of the slab, so it is a better measure form of "strong column and weak beam".At this time, the moment increasing coefficient of the first and second seismic grade of the seismic code still needs to be improved.
【作者单位】：重庆大学;重庆大学山地城镇建设与新技术教育部重点实验室;中冶建筑研究总院有限公司;
【基金】：国家自然科学基金(51178487)
【分类号】：TU311.3;TU375.4

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