【作者】 汤序霖；

【导师】 蔡健；

【作者基本信息】 华南理工大学 ， 结构工程， 2014， 博士

【摘要】 钢管混凝土柱-混凝土梁的连接形式构造多样，存在节点区域梁纵筋与柱钢管空间上的不协调，处理较为复杂。目前关于钢管混凝土柱-混凝土梁节点的研究尚不系统，存在节点力学性能与施工便利性不能两全等问题。研究开发受力性能良好、构造简单、施工方便的节点形式是研究人员与设计者急待解决的课题。本文提出一种新型的柱钢管节点区全断开的矩形钢管混凝土柱-混凝土梁节点。该节点的特点：柱钢管在节点区域断开，保证楼层框架梁纵筋贯通节点；通过扩大节点截面及配置多层约束钢筋网以解决因柱钢管断开和采用低强度等级混凝土而导致承载力下降问题；在多层钢筋网外围竖向配置密集箍筋，改善节点区混凝土的抗裂性能；节点区可不配置柱箍筋，通过钢筋网与密集箍筋形成的新型钢筋笼整体承受节点剪力。该新型节点具有的优点：节点可与任意方向的楼盖梁连接，楼盖梁的布置灵活；节点的抗裂能力提高，有利于扩大结构的正常使用范围；现场钢结构的焊接工作减少，施工较为方便。本文对该新型节点的轴压、偏压静力性能以及抗震性能进行研究，主要包括以下几个方面的工作。（1）进行了48个节点区试件的轴压试验，研究节点核心区的截面系数、高度系数β、配筋系数ρ、混凝土强度fcu以及柱长宽比γ对新型钢筋网节点核心区轴压力学性能的影响。试验表明，通过新型钢筋网的约束与扩大节点截面的局压作用，节点具有较高的轴压承载力和较好的延性；钢筋网外围布置密集箍筋可提高节点区的抗裂能力。（2）在约束混凝土本构关系的基础上，采用等效侧向应力的概念，计算钢筋网约束混凝土抗压强度，同时考虑混凝土的局压作用，获取该类新型节点的核心混凝土峰值强度。借鉴Mander本构形式，提出可适用于该类节点分析的等效单轴本构关系。采用该本构关系对轴压试件的等效应力-应变关系进行全过程计算，并与试验结果比较，两者吻合良好。（3）进行了8个带上下柱的新型节点试件受压试验，研究节点截面系数、高度系数β、柱长宽比γ对试件破坏形态、峰值承载力、各裂缝宽度对应荷载等力学性能的影响。通过与工程上采用的常规钢管混凝土柱承载力计算对比，合理设计的节点在轴压、小偏压荷载下的峰值承载力可高于钢管混凝土柱，满足“强节点，弱构件”的设计理念。同时节点区配置外围箍筋能够限制节点核心区外混凝土的竖向膨胀变形，限制各个侧面水平裂缝的产生和发展，有效地改善节点的抗裂性能。（4）在局压承载力理论的基础上，对混凝土局压与横向钢筋网约束双重作用机理进行分析，通过引入节点高度系数对已有的规范计算公式进行修正，提出该节点的轴压承载力计算公式一；并在此基础上，考虑偏心对局部受压承载力的折减，建立了该新型节点的偏压承载力计算公式。在Mander约束混凝土公式的架构下，考虑混凝土局压对横向钢筋网约束的影响作用，确定本试验环境中有效约束系数ke的计算方法，提出该节点轴压承载力计算公式二。根据试验现象，提出该节点峰值状态下试件受压有效截面的概念，并确定试件受压有效截面的计算方法，建立该节点轴压承载力计算公式三。通过验证比对，上述公式均可较精确地预测试验结果。（5）进行了5个试件的低周反复荷载试验，研究该新型节点的抗震力学性能。试验结果表明，随着相对配筋系数（节点体积配筋率/梁配筋率）与节点面积增大系数（节点面积/柱面积）的增大，破坏区域由节点区向框架梁根部转移，说明通过合理设计的节点在低周反复荷载作用下的受力性能是安全可靠的，可实现“强柱弱梁，节点更强”的抗震设计原则。对静力反复荷载作用后的节点试件进行轴压试验，结果表明在经历低周反复荷载作用后，节点钢筋网仍能有效约束节点核心区混凝土，节点仍具有较高的承载力与延性，说明通过合理设计的新型节点在震后也能体现“强节点，弱构件”的抗震理念。（6）在MCFT理论的基础上，确定新型节点计算关键参数的取值方法，提出了该新型节点抗剪承载力的计算方法。节点峰值剪应力计算结果与试验吻合良好，表明上述抗剪计算方法较为合理。更多还原

【Abstract】 There are different constructions types of the joint of concrete filled steel tubular (CFST)columns connecting with reinforced concrete (RC) beam in which the longitudinalreinforcement bars in RC beam are interrupted by the continuous steel column tube, resultingin the construction of the joint is more complicated. The research results about the joint arenot systematic. In most cases, the mechanical behavior is incompatible with convenientconstruction. It is urgent for researchers and designers to develop a new joint type withexcellent mechanic behavior, convenient construction and significant commercial benefits.In this paper, a new type of joints between rectangular CFST column and RC beam withdisconnection column tube in joint zone is presented. The main features of this joint are asfollow: The steel tube is disconnected at the joint zone, and the column tube is separated ineach floor, so the longitudinal reinforcement bars in RC beam can be continued in the zone.Because the column disconnection and the lower strength concrete to be using in the jointzone leading to the decrease of compression capacity, the enlargement of the section of jointand mesh reinforcement are used to strengthen the joint zone. The stirrups are set along theouter mesh reinforcement to improve the capability of ant-crack. The column stirrups settingin the zone of normal joint do not need, because the mesh reinforcement and stirrups alongthe outer mesh reinforcement can resist the force of joint shear. The advantages of this newtype of joint include the following aspect: the joint can be used to connect to any directionbeams; The crack resistance of joint is effectively improved with stirrups along the outer meshreinforcement; It is more convenient to construction because the steel connection parts arereduced.The paper focuses on the mechanical behavior of this joint, and the innovation researchworks are as follow.(1) Experimental studies were carried out with48rectangular specimens to investigatethe axial compression behavior of this type of joint. The main parameters in the experimentare the relative section of joints (the edge length of the joint section/the edge length of thesection column), the relative height of joints β (the height of the joint/the edge length of thesection column), the mesh reinforcement ratio ρ, the strength of concrete fcuand the length towidth ratio of column γ. The results show that, under the confinement of the meshreinforcement and enlargement of the section of joints, this type of joint has high compressivecapacity and ductility. By setting the stirrups along the outer mesh reinforcement, thecapability of ant-crack can be improved. (2) Based on the local compression formulas and conception of equivalent lateralcompressive stress in confined concrete, the peak strength of the core concrete in the joint iscalculated. The constitutive relationship of confined concrete is adopted to build theequivalent stress-strain relationship for the core concrete of the joint. This stress-strainrelationship takes a similar form of the constitutive model of confined concrete while itsparameters are modified to fit this type of joint according to experimental results. Finally, acalculation of complete stress-strain relationship curves is conducted for experimentalspecimens using this constitutive relationship. The calculation results and the experiment onesare in good agreement with each other.(3) Experimental studies were carried out with8rectangular joint specimens havingupper and lower columns, to investigate the eccentric compression behavior of this type ofjoint. The main parameters in the experiment are the relative section of joints, the relativeheight of joints β and the length to width ratio of column γ. The influence of the parameters onthe eccentric compression capacity of the joint was discussed. Comparison between theexperimental eccentric compression capacity of the joint and the calculated compressioncapacity of the CFST column with the methods of standard formula shows that thecompression capacity of the joint zone is higher than the column with the reasonable design.The results indicate that this type of joint can meet the anti-seismic design principalrequirement of strong joint-weak member. By limiting the vertical expansion deformation ofconcrete with stirrups along the outer mesh reinforcement, the emergence and development ofeach side horizontal crack can be postponed, and the crack resistance of joint is effectivelyimproved.(4) Based on the theory of local compression of concrete, the confining effects of localcompression of concrete and steel reinforcement bars to the concrete were discussed. Byintroducing the joint height coefficient, the Chinese standard formula was modified toestablish the formula Ⅰ for the ultimate axial compression capacity of joint. Based on theformula Ⅰ, by introducing the eccentric bearing capacity reduction coefficient for localcompression, the formula for calculating the eccentric bearing capacity of joint wasestablished. Based on the Mander confined concrete theory, the effective restraint coefficientkeunder local compression was discussed. Then, the formula Ⅱ for the ultimate axialcompression capacity of the joint was established. On the basis of the experimentalobservations, the concept of effective compression section was submitted. The formula Ⅲwas put forward to predict the ultimate axial compression capacity of the joint. The results predicted by above formulas are in good agreement with the experimental ones.(5) Cyclic loading experimental studies were carried out with5interior joint specimensto investigate the seismic behavior of this new type of column-beam joint. The results showthat the failure region from the joint to the frame beam with the increase of relativereinforcement ratios (the ratio of joint mesh reinforcement/the ratio of beam reinforcement)and relative dimension of joints (the section area of the joint/the section area of the column).With the reasonable design, the new type joint has good seismic behaviors, and the seismicprinciple “weak beam strong column, stronger joint” can be satisfied. The axial compressionexperiment on four specimens after the cyclic loading was carried out. The results show thatthe concrete in the joints can be still confined by the mesh reinforcement after the cyclicloading. The joint has high compressive capacity and ductility. With the reasonable design,the capacity of the joint zone is higher than the concrete filled steel tubular column, meetingthe anti-seismic design principal requirement of strong joint-weak member.(6) Based on the modified compression filed theory (MCFT), the key parameters of shearcapacity calculation for the new type joint were studied. The calculation method for shearcapacity was set up. The calculation results are in accordance with the experimental ones. Itcan be thought suggested calculation method is reasonable.更多还原