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951.
现代无金属地磁观测室研究的若干观点和建议 总被引:3,自引:3,他引:0
对现代无金属纤维混凝土结构和纤维砌块结构地磁观测室设计与建造研究,进行了回顾介绍和发展前景展望,介绍了这两种新型建筑结构的特点及其关键技术要点,提出了进一步发展复合碳纤维或玄武岩纤维替代金属材料的若干观点和建议,对地震监测台站的建设具有重要参考价值。 相似文献
952.
采用淤背方式加固黄河大堤时,河南、山东一期工程堤身多处出现裂缝。目前尚无淤背对堤身影响的定量研究成果,因而放淤固堤的合理施工速率难以确定。淤背体及堤防土体的水分消散过程实际上是非饱和流固耦合问题;淤背分级施工的变水头边界问题,可等效成多级常水头边界问题。采用非饱和渗流分析方法,计算出每级施工后堤防及淤背体的浸润线;将其作为已知边界条件,考虑堤防土体力学特性、排水条件等影响,进行非饱和流固耦合分析,据此提出相应的淤背施工合理速率。研究表明,该模型计算结果与实际情况相符,因而可为黄河标准化堤防工程设计与施工提供理论依据,并可供其它河流治理时参考。 相似文献
953.
包裹式土工格栅加筋土挡墙在工程中的设计分析仍采用基于极限平衡理论的锚固楔体法,而没有考虑在达到极限平衡之前加筋土挡墙所发生的变形发展和积累过程。加筋土挡墙面板的水平位移是墙体内外部稳定的重要体现。通过采用有限元数值方法,分析了不同工程因素对包裹式土工格栅加筋土挡墙面板处工后水平位移的影响,分析结果表明,FEM计算值和实测值接近,说明了有限元计算分析的适用性;包裹式土工格栅加筋土挡墙面板处的工后水平位移呈由下向上增大趋势;拉筋刚度、长度、竖向间距对水平位移具有明显的影响并应选择适宜数值,以实现加筋土挡墙的良好工程性能;挡墙墙顶处外荷载大小及位置对水平位移具有相应影响,位于加筋区外的外荷载对墙面水平位移影响不明显。 相似文献
954.
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956.
为了分析型钢混凝土异形柱的耐火极限及火灾后的力学性能,为试验研究做好充分的前期准备,本文采用有限元分析软件ANSYS对型钢混凝土异形柱截面温度场进行数值模拟,得出了柱截面在不均匀受火情况下的温度场分布规律。结果表明,在两面受火的情况下,L形柱的凹角处的温升低于其它部位;由于型钢的存在,加快了柱截面内部温度的热传导;距离受火面相同的深度处的混凝土与型钢的温度不同,因此有必要研究损伤差异对承载力和两者粘结滑移造成的影响。 相似文献
957.
Minarets are very slender structures with an old existence. The historical ones are made of cut‐stone‐block masonry assembled in peripheral cylindrical wall with an interior helicoidal stair supported on a central core and on the wall. They are spread throughout the Islamic world and constitute an important heritage not only of religious value, but also of great cultural interest. Throughout the times, these structures as part of a mosque, have suffered significant damage during the earthquakes. Istanbul presents interesting characteristics to evaluate their dynamic behavior, as they are in great number, in an area where a large event in the next 30 years has been predicted. In this paper, we performed a series of in situ ambient vibration tests to old minarets of various sizes and compared results of frequencies with numerical modeling of the same structures. For the low‐amplitude motion, the frequency values of the first modes can be obtained from an empirical formulae function of the inertia of the cross‐section and of the height of the main ‘body.’ Damping ratios for these amplitudes are of the order of 0.5–1.0%. Dynamic linear analyses of these structures indicate that for most cases very high stresses develop for PGA above 0.5 g, an input with a reasonable chance of occurring in the next 30 years. These high stresses are expected to cause the toppling of the minarets in the form that has been observed in the recent past events. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
958.
The evaluation of the out‐of‐plane behaviour of unreinforced walls is one of the most debated topics in the seismic assessment of existing masonry buildings. The discontinuous nature of masonry and its interaction with the remainder of the building make the dynamic modelling of out‐of‐plane response troublesome. In this paper, the results of a shaking table laboratory campaign on a tuff masonry, natural scale, U‐shaped assemblage (façade adjacent to transverse walls) are presented. The tests, excited by scaled natural accelerograms, replicate the behaviour of external walls in existing masonry buildings, from the beginning of rocking motion to overturning. Two approaches have been developed for modelling the out‐of‐plane seismic behaviour: the discrete element method and an SDOF analytic model. Both approaches are shown to be capable of reproducing the experimental behaviour in terms of maximum rotation and time history dynamic response. Finally, test results and numerical time history simulations have been compared with the Italian seismic code assessment procedures. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
959.
讨论生石灰深层搅拌强度形成机理,加固处理软基的有效性和应用条件。该方法具有设备简单、施工方便、工期短、经济效益好等特点。 相似文献
960.
Hossein Agha Beigi Constantin Christopoulos Timothy Sullivan Michele Calvi 《地震工程与结构动力学》2015,44(7):997-1014
This paper presents results from a numerical investigation into the seismic retrofit of a soft story frame using a novel gapped‐inclined brace (GIB) system. The GIB system consists of a pinned brace and a gap element that is added to the first story columns of the frame. The inclusion of GIB elements in addition to increasing the lateral capacity of columns at the first story increases the post‐yield stiffness ratio of the system and reduces the P‐delta effects on the columns, while not increasing the first story lateral resistance or stiffness. This allows for the isolating benefits of the soft story to protect the upper floors of the structure from damage while avoiding excessive deformations and reducing the propensity for collapse. A six‐story RC frame with masonry infills on all floors except for the first floor is studied. The dynamic response of the retrofitted building using the GIB system is investigated numerically and is compared with the response of the original un‐retrofitted building and the same building in which masonry infills are added to the first story to mitigate the soft story response. Results from the nonlinear time‐history analyses indicate that the GIB system could provide a reliable seismic retrofit mechanism for soft story buildings, which greatly reduces the likelihood of collapse by increasing the displacement capacity of the soft storey and by reducing P‐delta effects, while minimizing the overall damage and losses in the building by taking advantages of the isolation that is provided by the soft story to the rest of the structure located above. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献