【作者】 牛犇；

【导师】 陈志华；

【作者基本信息】 天津大学 ， 结构工程， 2014， 博士

【摘要】 随着我国综合国力的提高和经济的发展,建筑形式呈现出多样化的发展趋势。现代钢结构正朝着高、大、复的方向发展,复杂钢结构的大跨、高层建筑愈来愈多,它们在施工过程中的力学问题也越来越受到广泛的关注。针对弦支穹顶叠合拱结构,就预应力张拉过程中空间钢拱是否与下部网壳结构协同受力,制定了两种施工方案。对此两种施工方案,分别进行了弦支穹项叠合拱结构施工全过程分析,对预应力张拉施工过程中索力、杆件内力和结构变形进行了全过程分析。为满足预应力施工过程的需要、保证工程顺利进行,对结构进行施工监测,从监测结果来看,实测结果很好地验证了理论计算结果,同时说明了通过有限元计算软件进行施工仿真计算的可行性。对大跨度大悬挑吊挂结构施工过程中的关键技术问题进行研究,并进行了施工过程力学模拟分析。针对本工程的结构特点,确定了临时支撑的设置原则和卸载方案,采用等效杆端位移法进行临时支撑的卸载数值模拟。对大悬挑结构卸载进行了数值模拟及施工监测。针对钢框架-支撑与空间交叉桁架复合结构施工中的重点难点,对结构施工变形控制措施及结构整体卸载进行了施工过程有限元分析模拟,考察荷载转换过程中结构的强度与刚度变化,为施工方案的确定提供理论支持,保证施工过程的顺利进行。采用电阻应变片静态有线应力监测、电阻应变片静态无线应力监测和钢弦式应变传感器应力监测三种监测手段,对天津图书馆钢框架-支撑与空间交叉桁架复合结构关键节点的应力状态进行施工全过程监测。三种手段监测结果相互对照,可以及时发现问题,保证了监测结果的准确性和有效性,以及现场施工的顺利进行。将向心关节轴承引入弦支穹顶结构的撑杆上节点,形成了向心关节撑杆上节点,配合不可滑动撑杆下节点以及撑杆形成了向心关节索杆体系。选取工程实际向心关节轴承撑杆上节点进行了足尺试验,并进行了有限元模拟。提出了基于非线性有限元技术的反分析方法,分析了向心关节索杆体系弦支穹顶结构的施工张拉过程,确定了其施工放样状态。对向心关节索杆体系弦支穹顶结构张拉过程进行施工监测,通过监测各张拉阶段上部结构位移、支座位移,确保张拉过程中结构安全可靠,同时验证了施工张拉数值模拟方法的可行性。对切割加长大跨度结构滑移施工技术的总体思路和实际关键控制点进行了研究,通过对腹杆加强、支撑架搭设、滑移顶推点设计、滑移过程中的同步控制等技术措施进行研究,保证了工程的顺利实施。为了评定其滑移过程中桁架结构的安全性,使结构在滑移过程中保持同步且不因应力过大产生过大的变形,实现桁架整体滑移施工,并且满足其后续施工和使用的要求,对该桁架结构整体滑移过程中的部分关键杆件应力应变进行了现场监测。针对以上几种不同形式的大跨度空间钢结构,根据其结构受力特点、结构布置形式和现场工作条件等因素,确定相应的测点布设方式,力争达到“监测完整、性能稳定兼顾性价比最优”的布设原则,为今后相关结构工程的施工监测方案确定提供参考和理论依据。更多还原

【Abstract】 Considering whether space steel arch and lower reticulated shells work together in the process of tension, two kinds of construction programs about suspen-dome with stacked arch structure is made. Based on those programs, analyses of the whole construction process are conducted about the entire structure and cable force, member forces and structural deformation in the period of tension. Construction monitoring was done in order to guarantee the construction carrying on smoothly. Monitor results verify the theoretical results well and prove the feasibility of the construction simulation by finite element software.Research and mechanical simulation on key technical problems and in construction process of large span overhanging structure was done. Design principles of temporary supporting and unloading plan for this program was determined focusing on the its characteristics. Numerical simulation of temporary supporting was done by equivalent displacement method. Optimal way for casting concrete of suspension floor was determined by comparison and selection of different schemes and numerical calculation, which guaranteed the construction going on smoothly.Aiming at key problems in the period of construction of a complex steel structure system which combines steel frame-supporting system and intersected trusses, deformation control measures in construction and uninstall of the whole structure are simulated by the finite element. Meanwhile changes of strength and stiffness of the structure in loads conversion process are studied. All of those analyses can provide theoretical support to the determination of construction programs and can ensure the construction process running on smoothly. Three methods, electric resistance static strain testing system, electric resistance dynamic strain testing system and vibrating wire strain gauge system were used for monitoring. The stress of key joints of Tianjin library which combines steel frame-supporting system and intersected trusses is monitored in the whole constructing process. Results of these 3 ways are in accordance with each other, which guaranteed the smoothness of construction procedure and the accuracy and validity of monitoring results.Radial spherical plain bearing is brought into the cable-member systems of Suspended-dome as the rigid rotational core of strut up-joint, which forms the radial spherical plain cable-member system alongside the non-sliding cable strut joint. Full Scale axial loading tests as well as FEM calculation were carried out. Analysis method based on non-linear FEM is proposed. The tensioning process of cable dome with radial spherical plain cable-member system was analysed, its lofting state was also determined. Construction monitoring of tensioning process was carried out. Displacement of upper structure and bearing as well as the pre-tress of cables were monitored, which not only guaranteed the safety and reliability of structure but verified the numerical simulation method of tensioning process.Research on the general idea and key points in actual process of sliding construction method for cutting and lengthening long span structure was done. By the study of strengthening web members, erection of supporting frame, designation of pushing point and synchronization controlling etc., the program carried successfully.In this paper, arrangement of measuring points about mentioned different forms of large span steel structure is determined by mechanical characteristics, structure arrangement working conditions on site and so on. Meanwhile those measuring points are laid in the principle of striving to achieve “integrity monitoring, taking both stable performance and excellent value for money into consideration”. All of those studies can provide a reference for future related projects on construction monitoring.更多还原