薄壁箱体内模现浇空心筏板基础内力分析及设计方法研究

【作者】 王利平；

【导师】 刘立新；

【作者基本信息】 郑州大学 ， 结构工程， 2007， 硕士

【摘要】 现浇混凝土空心结构是顺应我国可持续发展基本国策，并随着新材料和施工新技术的出现而发展起来的新型结构形式。现浇混凝土空心筏板基础以埋入筒芯、箱体等轻质填充材料为手段，具有减少混凝土的用量、消解混凝土在凝固过程中的体积收缩及水化热、减少基础温度—收缩裂缝等优点，在多高层建筑中应用前景广阔。目前应用中最大的薄弱环节是进行现浇空心筏板基础设计时的受力分析。在总结前人已有的研究工作以后，本文主要完成了以下研究工作：1、对在实际工程中广泛应用的现浇空心楼盖结构和筏板基础体系进行总结，提出了平板式薄壁箱体内模现浇混凝土空心筏板基础体系，并分析比较其优越性。2、采用通用有限元软件ANSYS对同条件下的空心筏板基础和实心筏板基础的整体受力性能进行分析。分析结果表明：1)空心筏板基础和实心筏板基础的受力性能基本相同。空心板的应力、挠度及弹簧反力的分布均与实习筏板相似。空心筏板基础的内部空腔削弱了截面的抗弯刚度，在空心箱体与实心肋交界处存在应力集中现象，挠度较实心筏板基础略微增大。2)通过对中间区格、边区格和角区格的弯矩进行分析，得到空心筏板基础的截面弯矩及板带弯矩分布与实心筏板基础是相近的。弯矩向支座处“转移”。3)混凝土强度的提高能改善筏板的受力，减小差异沉降。混凝土强度等级为C30～C40之间为宜。4)地基基床系数的提高使地基刚度增大，对改善筏板的不均匀变形有利。3、依照我国相关规范、规程的规定，给出了平板式薄壁箱体内模现浇混凝土空心筏板基础的设计建议，并提出了一些施工中应采取的特殊措施。最后采用PKPM设计软件分析一简单筏板基础，将有限元分析结果与采用PKPM所得分析结果进行比较，并进行修正，从而为广大设计人员提供设计参考依据。更多还原

【Abstract】 The cast-in-situ reinforced concrete hollow structure is complied with our country’s basic national policy of sustainable development, and it is a kind of new-style structure that is developed with the advent of new building materials and new construction technology. The cast-in-situ concrete hollow raft foundation is a new type foundation system in which the lightweight filling materials such as tube fillers and box fillers are laid as internal mold. It has application prospect in multi-storey buildings for its advantages: reducing concrete amount, abating volume contraction and heat of hydration in solidification process of concrete, and decreasing temperature cracks and shrinkage cracks. At present the biggest weakness in application is the stress property analysis in design of the cast-in-situ concrete hollow raft foundation.After summarizing the researching works of earlier scholar, the thesis accomplished the main subjects as follows.1 The cast-in-situ concrete hollow floor system and raft foundation system used widely in the factual engineering are summarized comprehensively so as to put forward the plate type thin-wall core box cast-in-situ reinforced concrete hollow raft foundation system , and analyzes its superiority.2 The stress properties of solid and hollow raft foundation under the ideal constraint condition are studied in this thesis by using finite element method ANSYS. The result of analysis shows that:1) The stress performance of hollow and solid raft foundation is similar. The distribution of stresses, displacement, and reaction of spring on hollow raft foundation are similar to the solid raft foundation . The cavity in the hollow raft foundation leads to the decrease of flexural rigidity. It has the phenomenon of stress concentration at the intersection of hollow box and solid rib, and the deflection increases slightly.2) The moment distribution in interior panel, edge panel and comer panel are analyzed. The result shows that the distribution of section moment and strip moment of the hollow raft foundation is close to the solid raft foundation. And the moment shift to the support saddle.3) The enhancement of concrete intensity can improve the stress property of raft foundation , and reduce uneven settlement. The thesis proposed that the concrete intensity ranks between C30-C40 is suitable.4) The enhancement of coefficient of subgrade reaction can increase the stiffness of ground, and it has advantage of reducing uneven settlement.3 According to the specify of related code and specification in our country, this paper gives some suggestions about design of the plate type thin-wall core box cast-in-situ reinforced concrete hollow raft foundation, and proposes some special measures in construction. Finally, one simple raft foundation is analyzed by using PKPM which is an engineering design software, and the calculation results of PKPM are compared with the analysis results of ANSYS, and also revision is carried on. Thus it provides design reference to the common designers.更多还原