填充墙与钢框架协同工作性能非线性分析   总被引：5，自引：2，他引：5  

戴绍斌  余欢  黄俊 《地震工程与工程振动》2005,25(3):24-28

在试验研究的基础上，运用ANSYS有限元中的接触单元建模，对加气混凝土填充墙钢框架的结构性能进行了研究，同时与纯钢框架结构在强度、刚度、以及延性等方面进行了对比分析，结果表明：填充墙与钢框架协同工作能够改善钢框架结构的受力性能和抗震能力，这为钢结构及其围护体系的研究与推广应用提供了一定的理论依据。  相似文献   

十八烷基三甲基铵改性蒙脱石的结构和凝胶性能关系研究   总被引：1，自引：2，他引：1  

邱俊  吕宪俊 《矿物岩石》2007,27(4):17-21

利用小角X射线衍射技术研究在不同的十八烷基三甲基铵盐用量下制备的有机蒙脱石的结构特征,将具有不同晶体结构特征的有机蒙脱石分别分散在二甲苯、乙醇混合相和0#柴油中,测定在相应溶剂体系中的凝胶性能,研究发现当十八烷基三甲基铵盐的用量小于0.9 CEC时,十八烷基三甲基铵盐阳离子在蒙脱石层间呈单层平卧排列,由于在有机溶剂中蒙脱石得不到充分的剥离而导致有机蒙脱石的凝胶性能较差,表现为有机凝胶的粘度和胶体率都较低;当十八烷基三甲基铵盐的用量在0.9 CEC~1.8 CEC时,十八烷基铵阳离子在蒙脱石层间呈单层倾斜排列,在有机相中蒙脱石不仅能得到充分的剥离,而且能形成稳定的"卡房式结构",使有机凝胶的黏度和胶体率分别最高达到23 000mPa.s和100%;而当十八烷基铵盐的用量大于1.8 CEC时,十八烷基铵有机物在蒙脱石层间呈胶束排列,尽管在有机相中能得到充分的剥离,但由于过量的有机阳离子中和了蒙脱石层面的负电荷,在体系中不能形成稳定的"卡房式结构",使有机蒙脱石的凝胶粘度较低,而胶体率较高。  相似文献   

Energy demands for seismic design against low‐cycle fatigue     

Amador Teran‐Gilmore  James O. Jirsa 《地震工程与结构动力学》2007,36(3):383-404

A seismic design procedure that does not take into account the maximum and cumulative plastic deformation demands that a structure is likely to undergo during severe ground motion could lead to unsatisfactory performance. In spite of this, current design procedures do not take into account explicitly the effect of low‐cycle fatigue. Based on the high correlation that exists between the strength reduction factor and the energy demand in earthquake‐resistant structures, simple procedures can be formulated to estimate the cumulative plastic deformation demands for design purposes. Several issues should be addressed during the use of plastic energy within a practical performance‐based seismic design methodology. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Expected loss‐based alarm threshold set for earthquake early warning systems     

Iunio Iervolino  Massimiliano Giorgio  Gaetano Manfredi 《地震工程与结构动力学》2007,36(9):1151-1168

Earthquake early warning systems (EEWS) seem to have potential as tools for real‐time seismic risk management and mitigation. In fact, although the evacuation of buildings requires warning time not available in many urbanized areas threatened by seismic hazard, they may still be used for the real‐time protection of critical facilities using automatic systems in order to reduce the losses subsequent to a catastrophic event. This is possible due to the real‐time seismology, which consists of methods and procedures for the rapid estimation of earthquake features, as magnitude and location, based on measurements made on the first seconds of the P‐waves. An earthquake engineering application of earthquake early warning (EEW) may be intended as a system able to issue the alarm, if some recorded parameter exceeds a given threshold, to activate risk mitigation actions before the quake strikes at a site of interest. Feasibility analysis and design of such EEWS require the assessment of the expected loss reduction due to the security action and set of the alarm threshold. In this paper a procedure to carry out these tasks in the performance‐based earthquake engineering probabilistic framework is proposed. A merely illustrative example refers to a simple structure assumed to be a classroom. Structural damage and non‐structural collapses are considered; the security action is to shelter occupants below the desks. The cost due to a false alarm is assumed to be related to the interruption of didactic activities. Results show how the comparison of the expected losses, for the alarm‐issuance and non‐issuance cases, allows setting the alarm threshold on a quantitative and consistent basis, and how it may be a tool for the design of engineering applications of EEW. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Effectiveness of simple approaches in mitigating residual deformations in buildings     

Didier Pettinga  Constantin Christopoulos  Stefano Pampanin  Nigel Priestley 《地震工程与结构动力学》2007,36(12):1763-1783

Developments in performance‐based seismic design and assessment approaches have emphasized the importance of considering residual deformations. Recent investigations have also led to a proposed direct displacement‐based design (DDBD) approach which includes an explicit consideration of the expected residual deformations as an integral part of the design process. Having estimated the expected residual deformations in a structure, engineers are faced with the problem of reducing them to meet the targeted performance levels under pre‐defined seismic hazard levels. Previous studies have identified the post‐yield stiffness as a primary factor influencing the magnitude of residual deformations in single degree of freedom and multiple degree of freedom structures. In this paper, a series of simple approaches to increase the post‐yield stiffness of traditional framed and braced systems for the purpose of reducing residual deformations are investigated. These methods do not utilize recentring post‐tensioned technology. This contribution addresses the feasibility of altering the lateral post‐yield stiffness of structural systems by: (i) using different reinforcement materials with beneficial features in their stress–strain behaviour; (ii) re‐designing the section geometry and properties of primary seismic‐resisting elements; and (iii) introducing a secondary elastic frame to act in parallel with the primary system. The efficiency of each of these techniques is investigated through monotonic and cyclic moment‐curvature and non‐linear time‐history analyses. Of these approaches the design and introduction of an elastic secondary system was found to be most effective and consistent in reducing residual deformations. A simplified design approach for achieving the desired increase of a system's post‐yield stiffness is also presented. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Improved seismic hazard model with application to probabilistic seismic demand analysis     

Brendon A. Bradley  Rajesh P. Dhakal  Misko Cubrinovski  John B. Mander  Greg A. MacRae 《地震工程与结构动力学》2007,36(14):2211-2225

An improved seismic hazard model for use in performance‐based earthquake engineering is presented. The model is an improved approximation from the so‐called ‘power law’ model, which is linear in log–log space. The mathematics of the model and uncertainty incorporation is briefly discussed. Various means of fitting the approximation to hazard data derived from probabilistic seismic hazard analysis are discussed, including the limitations of the model. Based on these ‘exact’ hazard data for major centres in New Zealand, the parameters for the proposed model are calibrated. To illustrate the significance of the proposed model, a performance‐based assessment is conducted on a typical bridge, via probabilistic seismic demand analysis. The new hazard model is compared to the current power law relationship to illustrate its effects on the risk assessment. The propagation of epistemic uncertainty in the seismic hazard is also considered. To allow further use of the model in conceptual calculations, a semi‐analytical method is proposed to calculate the demand hazard in closed form. For the case study shown, the resulting semi‐analytical closed form solution is shown to be significantly more accurate than the analytical closed‐form solution using the power law hazard model, capturing the ‘exact’ numerical integration solution to within 7% accuracy over the entire range of exceedance rate. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Prediction of the median IDA curve by employing a limited number of ground motion records     

Alireza Azarbakht  Matjaž Dolšek 《地震工程与结构动力学》2007,36(15):2401-2421

A methodology has been proposed which can be used to reduce the number of ground motion records needed for the reliable prediction of the median seismic response of structures by means of incremental dynamic analysis (IDA). This methodology is presently limited to predictions of the median IDA curve only. The reduction in the number of ground motion records needed to predict the median IDA curve is achieved by introducing a precedence list of ground motion records. The determination of such a list is an optimization problem, which is solved in the paper by means of (1) a genetic algorithm and (2) a proposed simple procedure. The seismic response of a simple, computationally non‐demanding structural model has been used as input data for the optimization problem. The presented example is a three‐storey‐reinforced concrete building, subjected to two sets of ground motion records, one a free‐field set and the other a near‐field set. It is shown that the median IDA curves can be predicted with acceptable accuracy by employing only four ground motion records instead of the 24 or 30 records, which are the total number of ground motion records for the free‐field and near‐field sets, respectively. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

超站仪HD-STGPS的检测及应用   总被引：1，自引：2，他引：1  

李军锋  朱贤元  刘进莆 《测绘信息与工程》2001,(2):43-44

简述了超站仪定位系统HD－STGPS的检测与应用，并得出了一些有益的结论与建议，供同行参考。  相似文献   

安全生产投入产出理论及模型研究   总被引：2，自引：0，他引：2  

黄盛仁  陆万雨等 《江苏地质》2001,25(2):122-125

系统地阐述了安全生产投入产出理论，并借助经济学知识建立了全国安全生产投入产出表，求出了一系列的方程和系数，这对于政府和企业制定其合理、科学的安全生产政策具有一定的指导意义。  相似文献   

活性白云粉生产工艺及其物化性能研究   总被引：1，自引：0，他引：1  

贾建业  汤艳杰  王辅亚  王杨传  宁平  王建成  魏俊峰 《矿物学报》2001,21(3):439-442

活性白云粉（ABP）是在白云岩经过破碎、细粉碎、表面改性的基础上得到的一种新型改性功能填料。本文利用河南辉县市的拍石头和张村两地产出的白云岩作为实验原料，对其表面改性的实验方法、改性剂选择及用量、改性条件及改性效果等方面进行了一定的探讨，并且对改性前后的白云石粉体的粒度、比表面积等性能及红外光谱特征做了对比研究。生产工艺和物性测试研究表明：活性白云粉代替轻质碳酸钙作橡胶填料前景广阔；与轻钙相比，活性白云粉的粒度不够均匀，经优化和改善生产工艺条件，可望进一步提高其应用价值。  相似文献