【作者】 岳欣宇；

【导师】 白绍良； 傅剑平；

【作者基本信息】 重庆大学 ， 结构工程， 2008， 硕士

【摘要】 本文通过5个按照《混凝土结构设计规范》(GB50010-2002)设计的配置HRB335纵筋的框架顶层端节点循环加载试验,验证了现行规范中框架顶层端节点采用柱内搭接方案时的抗震性能,分析了若林实搭接方案在框架顶层端节点应用中可能存在的问题,通过在节点中上部配置附加水平箍筋,提高了节点斜截面的抗弯能力,对若林实搭接方案进行了改进。本文所针对的具体问题以及主要结论如下:①框架顶层端节点梁、柱负弯矩钢筋的构造做法:本次试验第1个试件梁、柱负弯矩钢筋搭接方案采取《混凝土结构设计规范》(GB50010-2002)中框架顶层端节点柱内搭接方案,钢筋搭接长度等于1.7laE,柱外侧纵向钢筋伸至柱顶后向节点内水平弯折,弯折段水平投影长度为12倍纵筋直径,钢筋弯弧内直径等于6倍纵筋直径,试验结果显示此构造方案没有出现节点内穿过主弯弧柱侧端点附近及柱负弯矩筋顶点的薄弱面,验证了《混凝土结构设计规范》(GB50010-2002)规定的节点负弯矩钢筋柱内搭接方案的有效性;其余4个试件梁、柱负弯矩钢筋均采用若林实搭接方案,通过在节点中上部配置附加水平箍筋加强斜截面的抗弯能力,有效防止了节点内穿过主弯弧柱侧端点附近及柱负弯矩筋顶点的薄弱面的出现,对若林实搭接方案进行了有效的改进,并对附加箍筋的设置位置及数量进行了分析。②框架顶层端节点梁下部钢筋锚固:《混凝土结构设计规范》(GB50010-2002)中对顶层端节点梁下部钢筋采用和中间层端节点相同的锚固措施,90°弯折锚固的要求是水平段长度不小于0.4laE,外加15d的竖直尾段。已有试验结果和本次试验结果都显示此锚固措施的效果不是很理想。本次试验第5个试件把梁下部钢筋90°弯折锚固改为末端焊接锚板锚固,试验结果显示锚固效果有所改善。更多还原

【Abstract】 Five specimens of knee joints in reinforced concrete frames under cyclic reversed loading with HRB335 longitudinal steel designed basing on“Code for Design of Concrete Structures”(GB50010-2002) are tested, which verifies the efficiency of seismic measures in knee joints with the negative moment reinforcement and linear lapped splice joint located at outer side of column top. Meanwhile, relevant issues the application of Wakabajashi lapped method on knee joints are discussed. By disposing the horizontal stirrups in upside of knee joint, the bending resistance of oblique section in knee joint has been improved, and the Wakabajashi lapped method has been developed. The main points and conclusions are summarized as following:①Construction measures of knee joints in reinforced concrete frames in which the steel bears beam and column negative moment: The first specimen is tested through the method of locating the negative moment reinforcement linear lapped splice joint at outer side of column top according to“Code for Design of Concrete Structures”(GB50010-2002), in which the column flank longitudinal reinforcement horizontally bends to knee joint after its extending to the top of column, the bend length is 12 times of longitudinal steel diameters, the overlapping length in the knee joints is 1.7laE and the inner diameter is equal to 6d. The results of the test illustrate that the weak surface through the ratius of main bar and the apex of the negative moment reinforcement has not appeared. It also proves the efficiency of seismic measures in knee joints which designed basing on“Code for Design of Concrete Structures”(GB50010-2002). Other four specimens adopt Wakabajashi lapped method. And by disposing the horizontal stirrups in upside of knee joint, the bending resistance of oblique section in knee joint has been improved, and the Wakabajashi lapped method has been developed. Moreover, the located position and quantity of the additional horizontal stirrups has been analyzed.②The anchorage of bottom beam bars of knee joints in reinforced concrete frames: according to“Code for Design of Concrete Structures”(GB50010-2002), the anchorage measures of bottom beam bars in exterior joints is the same with that of knee joints in reinforced concrete frames. Meanwhile, the horizontal length of 90°hooked anchorage should be no less than 0.4laE and the length of end piece should be no less than 15 times of longitudinal steel diameters. The current test shows that the anchorage measure is not effective enough. But the anchorage measure has been improved when the bottom beam bars of the fifth specimen anchored with anchor plate.更多还原