【作者】 尚晓江；

【导师】 张维嶽； 肖从真； 王翠坤；

【作者基本信息】 中国建筑科学研究院 ， 工程力学， 2008， 博士

【摘要】 本文围绕高层建筑混合结构的弹塑性工作性能这一中心主题,在高层建筑结构弹塑性分析方法以及框架-核心筒结构模型振动台实验两方面开展研究工作,主要研究内容及研究成果如下:1.在总结和比较现有各种混凝土单轴本构模型的基础上,提出一个混凝土的单轴本构模型。该模型可以考虑反复荷载作用下材料的损伤以及荷载反向时的裂面刚度恢复行为,且易于程序实现。通过ABAQUS的开发接口,基于上述本构关系编制了用户材料子程序UMAT和WMAT,可分别结合隐式以及显式求解程序,通过纤维模型对梁柱构件进行非线性分析。2.探讨了通过显式动力求解程序进行结构静力非线性分析的相关问题和技巧。利用ABAQUS程序提供的混凝土弹塑性损伤模型,结合使用本文所开发的用户材料子程序,对一个拟静力实验的模型结构进行了静力推覆分析。计算结果与实验加载过程吻合较好,验证了混凝土纤维材料子程序及ABAQUS损伤塑性模型在高层建筑混合结构体系弹塑性分析中应用的有效性。3.以30层型钢混凝土框架-核心筒结构为原型,按几何缩尺1:15设计制作了以砂浆为主要材料的振动台实验模型,并在中国建筑科学研究院抗震实验室进行了振动台实验。实验的加速度相似比为1:1,模型结构经历了相当于8度小震到9度大震的单向水平地震动输入。实验结果表明:型钢混凝土框架-核心筒结构表现出良好的承载能力,在8度中震作用下基本处于弹性工作阶段,最终破坏模式为整体倾覆破坏,核心筒在根部被拉断。基于实验结果,分析了结构的动力响应、自振特性、变形特征以及构件的受力特点,指出了当前设计方法存在的问题,并提出了相应的设计建议。4.按照振动台实验模型底层柱的尺寸和高度制作了一组构件,对其进行了不同轴压比条件下的低周反复加载实验,得到模型构件的滞回曲线和正截面承载力相关曲线。实验结果证实,模型构件的破坏也存在大小偏压之分,正截面相关曲线特征及破坏形状与原型构件类似,轴压、纯弯以及偏压屈服承载力基本符合相似条件。5.按照实验模型砂浆的力学性能指标,构造了抛物线和直线分段型的砂浆受压应力-应变曲线以及多折线受拉应力-应变曲线。对振动台实验的模型结构进行了弹性以及弹塑性时程分析,地震波采用实验中各工况实际输入的基底加速度时程。计算结果表明,用户材料子程序正确实现了反复荷载作用下的砂浆应力-应变关系,较好的模拟了反复荷载作用下的损伤以及裂面接触行为。在小震阶段,计算与实验吻合较好。由于分析中未考虑多波作用引起的损伤累积,在后续工况的计算变形值小于实验变形值,但是计算结果基本反映出了振动台实验的模型破坏过程及结构受力特点,且动力骨架线与实验动力骨架线吻合较好。6.对文献[37]拟静力实验和本文振动台实验进行了全面的比较,研究表明,两个实验的结构破坏形式和弹塑性受力、变形特点基本一致。经过换算的原型结构骨架线在小震和中震阶段基本保持线弹性并且基本重合,实验相似关系在此阶段得到了较好的满足。动力骨架线在弹塑性阶段高于静力骨架线,振动台实验模型破坏时的总体损伤程度和裂缝数量也不及拟静力实验。此外,振动台实验的顶部楼层框架破坏严重,这与拟静力实验显著不同。7.基于本文的弹塑性分析结果,讨论了在静力、动力荷载作用下基底剪力和倾覆力矩在底层框架以及核心筒之间分配的特点。研究表明,框架作为抵抗侧向作用的第二道防线,在弹性阶段分担基底剪力中很小的一部分,随着结构进入塑性阶段框架柱分担的基底剪力有所提高;但是在抵抗整体倾覆破坏方面,无论是弹性阶段还是弹塑性阶段框架和核心筒的作用都同等重要,框架并不是仅仅起到第二道防线的作用。更多还原

【Abstract】 Focusing on the seismic performance of hybrid tall building structures, two aspects of study, elasto-plastic analysis method and shaking table test of frame-core tube model, have been carried out in this dissertation. The main research contents and results are as follows:1. After summarizing and comparing the Existing uniaxial stress-strain models of concrete, a model which can calculate the damage and stiffness recovery effects during cyclic loading is presented, and based on which user material subroutines UMAT and VUMAT have been developed through the interface of ABAQUS program. These two subroutines can be used in conjunction with implicit and explicit solver respectively to analyze the nonlinear behavior of beam column members with fiber model.2. The related issues and techniques in static nonlinear analysis using explicit dynamic solver have been discussed. The push-over analysis of a pseudo-static test model structure has been carried out by using the ABAQUS damaged plasticity model for concrete and the user material subroutines developed. The analysis results agree well with the loading process of test, which shows the validity in the elasto-plastic analysis of hybrid tall buildings by using the ABAQUS damaged plasticity model and the user material subroutines.3. 1:15 scale model of a 30 storey frame-core wall hybrid structure with main material mortar was designed and built. The shaking table test of this model has been carried out in the seismic lab of CABR. The similarity ratio of acceleration is 1:1,and the model experienced the action of the single-direction seismic wave with the amplitude from 70gal to 620gal. The test results indicate that the frame-core wall hybrid structure model has performed almost with a elastic behavior under the action of seismic wave of moderate earthquake with the intensity of VIII. The final failure mode of the structure is overturn, the bottom of the core-tube is pulled out. The related issues, such as dynamic response, free vibration characteristics, structure deformation and stress in member sections have been studied through the experimental results. The problems of the existing design method have been pointed out and the corresponding suggestion for design have been put forward.4. A group of members with the same section and height of the columns in the first floor of the above shaking table test model have been tested under low cyclic reversed loading with different axial compression ratio, the hysteresis loops and the relation line of ultimate axial force and bending moment have been obtained. It can be indicated from the test that the failure modes of these members can also be divided into tensile failure and compressive failure. The shape of relation line is similar to that of the prototype members. The yielding axial compressive forces and yielding bending moments with and without axial force satisfy the similarity conditions approximately.5. A stress-strain curve has been fitted for the mortar in the shaking table test model based on the material properties data. Elastic and Elsto-plastic time history analysis of the above model in the shaking table test have been done. The calculated results show that the user material subroutines realize the stress-strain relationship of the mortar and the stiffness degradation and stiffness recovery effects during cyclic loading have been well simulated. The analysis results agree well with the test results during elastic phase. The analysis ignored the damage cumulation between different analysis cases, hence the calculated displacement of the subsequent cases is less than that of the test, but the analysis results reflect the main characteristics of the loading process of the test and the calculated dynamic skeleton curve agree well with that of test.6.An overall comparison between the pseudo static test in Ref. 37 and the shaking table test above is given. It is shown that the failure modes and the characteristics of structure stress and deformation of two tests are approximately the same. The static and dynamic skeleton curves of the prototype model remain linear elastic under the action of moderate earthquake, the experimental similarity conditions agree very well during the elastic phase in both tests. In the plastic phase, the dynamic skeleton curve is higher than the static skeleton curve, the overall damage of shaking table test is slighter than that of the pseudo test. There is serious damage in the frame columns at the top of the model in the shaking table test, which is obviously different from the pseudo test.7. The base shear and the overturning moment distribution between the bottom frame and core tube have been discussed based on the static and dynamic analysis results. It is indicated that the frame carries a very little portion of base shear during elastic phase and this portion increases during the plastic phase, the frame is the second line of defense to the shear. On the other hand, the overturning moment carried by the frame is comparable to that of the core tube, whether during elastic phase or plastic phase, the frame is not only the seconcd line of defense to the overturn failure.更多还原