【作者】 何文辉；

【导师】 肖岩；

【作者基本信息】 湖南大学 ， 结构工程， 2009， 博士

【摘要】 钢管混凝土钢梁体系是钢-混凝土组合结构的一种形式,当使用在弯矩抵抗框架中,因为由钢管混凝土柱的刚度控制结构侧移,故可充分发挥其轻质、延性好等优点;钢梁则具有自重轻、强度高、工期短和易于开孔以穿越建筑管道等方面的优势。钢管混凝土-钢梁组合体系是一种具有巨大开发与应用前景的新型房屋结构体系,但由于钢管混凝土柱-钢梁节点的多样性及其受力状态的复杂性,国内外对采用这类节点的框架结构的深入研究显得相对滞后,在一定程度上制约了这类组合结构体系的推广。国内外钢管混凝土柱-钢梁组合结构中研究和应用较多的梁柱刚性节点形式包括环梁连接、内外隔板连接、穿梁节点和T型件螺栓连接等多种方式,对框架整体性能进行的试验研究也基本上采取以上节点连接方式。其中,带环梁或隔板的节点连接方式所需现场施工作业较多,抗震性能也还需进一步深入探讨;穿心连续梁节点和T型件螺栓连接则在我国研究应用较少。高强螺栓端板连接是钢结构中常用的连接方式,在轻钢结构门式刚架中被普遍采用,国内外也有相应的设计规程。近几年已有研究者对其在钢筋混凝土结构和钢骨混凝土结构中的应用开展了试验研究,研究结果表明该类节点在钢-混凝土组合结构中具有良好的抗震性能,但其在钢管混凝土结构中的研究还较少。对于采用这种节点形式的H钢混凝土组合梁-钢管混凝土柱的框架试验研究,尤其是大比例模型试验,则相对更少,因此有必要开展这方面的研究。有鉴于此,本文基于现行美国规范并结合现中国规范,及以往研究者的相关成果,采用螺栓端板连接钢管混凝土-钢梁组合框架对一榀10层3跨平面框架进行了设计、分析与试验研究。设计理念着眼于采用基于性能的设计方法,建立了针对不同程度烈度水准地震灾害中结构需满足的性能目标。设计要求结构在多遇烈度水准(FOE)下的性能目标为不发生任何破坏;在基本设计烈度水准下(DBE)的性能目标为允许发生可以修复的破坏,但不允许形成强度退化;在罕遇烈度水准(MCE)下的性能目标为防止倒塌。针对钢管混凝土组合框架中各部分构件定义了一系列极限状态,并将之与各烈度水准的性能目标对应起来,作为评估构件在相应地震灾害中性能的依据。采用有限元程序OPENSEES对平面框架进行了建模模拟。对梁、柱及节点,参考相关研究进行建模;而对于端板螺栓连接钢管混凝土柱-钢梁节点域,则采用一种6结点非线性弹簧模型来进行模拟。建立的模型考虑了材料非线性和几何非线性等特征。在进行原型结构分析之前,采用建议的节点域模型对以往相似研究进行了对比,吻合程度较好。之后对模型进行了静力推覆分析和非线性时程分析,考察了原型结构在地震作用下的抗震性能。在时程分析中,采用一系列经过调整至FOE、DBE和MCE烈度水准要求的地震加速度记录对原型结构进行加载。调整之后的地震加速度记录反应谱分别满足规范目标反应谱的要求。有限元分析结果用来考察原型结构抗震性能并验证其是否满足设计需求。由于实际工程中地震作用存在不确定性,因此采用统计的方法对原型结构时程分析响应进行了评估。分析结果表明,原型结构满足给定的各项性能目标。综合考虑构件截面的强度、刚度、非弹性性能等因素,结合试验室场地情况与加载条件,采用相似比4/7对原型结构进行缩尺,作为抗震试验研究的测试结构。采用与原型结构建模相同的方法,建立了测试结构模型。对测试结构进行的静力推覆分析和时程分析结果表明,测试结构与原型结构在构件变形、层间位移及层间剪力等指标上与原型结构相近,可以对之进行试验以考察原型结构抗震性能。选取测试结构底二层一跨半作为试验子结构,而其上八层作为计算子结构,基于远程协同试验平台NetSLab,对测试结构进行了一系列抗震试验研究。包括对应于FOE、DBE和MCE烈度水准的子结构拟动力试验、对应于能安全使用试验室最大加载能力的超罕遇(MCE-After)烈度水准的子结构拟动力试验、采用美国钢结构抗震设计规范建议的加载制度进行的低周往复加载试验及采用单调加载方式进行的静力推覆试验。根据试验结果对原型结构性能目标进行了评估,并将之与有限元预测结果加以对比。对比分析显示,测试结果与预测结果吻合程度较好,测试结构在各次试验中均能达到预期的响应水准,验证了原型结构能满足给定的不同水准的性能目标,同时也验证了所建模型的合理性。结合理论分析与试验验证,采用端板螺栓节点连接形式的钢管混凝土-钢梁组合框架具有良好的抗震性能,适用于抗震地区的多高层框架结构;对于该类结构体系,可以采用本文建模方法对其性能进行预测与评估。更多还原

【Abstract】 Composite steel-concrete structures can make use of the attributes of each material, combining the speed of construction, strength, long-span capability, and light weight of steel with the inherent stiffness, damping, and economy of concrete. In the case of concrete filled tubular (CFT) columns, the tube replaces the formwork during construction, and confines the concrete infill during service, while the concrete infill restrains the local buckling of the steel tube, reducing the construction costs as well as the amount of transverse and longitudinal reinforcement required. Composite concrete filled steel tubular column-steel beam structure has proved very efficient in load capacity and construction, while the complexity of its connection and lack of large scale frame experimental research limit its further application.Previous studies on rigid CFT column-steel beam connection details focused on exterior diaphragm and interior diaphragm connections, stiffening ring connections, beam through column connections and welded or bolted split-tee connections. However, most of those connections need lots of in-situ welding labor work and/or their seismic behaviors still need further study. Prestressed high strength through bolted end-plate connection is widely used in steel structures. Several studies on its application in composite structures, such as steel-reinforced concrete column-steel beam connections and RC column-steel beam connections, have validated its superiority in seismic design. Some but still limited large scale composite CFT frame experimental investigations have been performed, especially on those with through bolted connections.Analytical and experimental studies on the seismic behavior of a composite frame with concrete filled steel tubular columns and steel beams were conducted. A prototype building was designed using current seismic provisions and recommendations from previous related research. The expected performance of the building was related to three seismic hazard levels, namely, the maximum considered earthquake (MCE) level, having a 2% probability of exceedance in 50 years, the design basis earthquake (DBE) level, having a 10% probability of exceedance in 50 years, and the frequently occurring earthquake (FOE) level, having a 50% probability of exceedance in 50 years. The building was expected to remain undamaged for FOE level earthquakes, have repairable damage and exhibit no strength degradation for DBE level earthquakes, and avoid collapse for MCE level earthquakes. A set of limit states was defined representing the degree of damage on the components of the frame, namely the H-shape beams, CFT columns, connections, and panel zones, and the occurrence of these limit states was related to each performance objective.An analytical model for composite concrete filled tubular columns-steel beam frame was developed and used to evaluate the prototype building performance. Models for the individual components of the composite CFT frame developed both by previous research (CFT plastic hinge region model, H-shape beam model, connection model) and as part of this study (a six-node nonlinear spring panel zone model) were utilized. The model accounted for material nonlinearities, including yielding and local buckling of steel and concrete cracking and crushing, as well as geometric nonlinearities. Static pushover and time-history analyses were conducted using the prototype building model to study the response of the building when subjected to a series scaled ground acceleration records representing the FOE, DBE and MCE levels, respectively. The scaling process consisted of matching the response spectrum of each record to the corresponding FOE, DBE or MCE target response spectrum, as defined in related seismic provisions. These simulations were used to evaluate the performance of the prototype building and verify it against the design requirements. The evaluation was carried out in statistical terms due to the variability associated with the seismic excitations. The prototype building was found to perform adequately for all performance objects in the three different earthquake hazard levels.A test structure model was constructed and analyzed with the same consideration of the prototype building model at a four-sevenths scale factor determined from laboratory space and loading capacity and similarity of the strength, stiffness and inelastic behavior between the prototype building members and available members in the market. It was found that the test structure model closely reproduced the response of the prototype building model in terms of element deformations, story drift, and story shear. The overall test structure was divided into two substructures with the bottom two stories to be tested physically while the upper eight stories to be simulated by trilinear model with lumped mass in a test platform NetSLab (Network Structural Laboratories), in which interactions between these two parts were considered. Based on symmetry, a one and a half bay, two-story test frame was built for the physically experimental phase of the study. The test structure was subjected to simulated seismic excitations corresponding to different earthquake hazard levels using sub-structuring pseudo-dynamic hybrid testing methodology. Quasi-static test and pushover test were also conducted to investigate the seismic behavior of the test sub-structure. The test structure performed in accordance with the performance objectives, confirming the conclusions drawn from the results of the analytical studies.Based on the results from the analytical and experimental studies, CFT frame with bolted endplate connections has adequate seismic behavior suitable for seismic resistant design.更多还原