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301.
The paper investigates the influence of design procedures on the seismic response of multi-storey asymmetric buildings. To
this end, some structures are designed according to methods based on either static or modal analysis, with or without design
eccentricities. The seismic response of these systems is determined by means of inelastic dynamic analyses and the design
is thoroughly examined in order to explain the results of the dynamic analyses. Attention is basically focused on the ability
of design methods to prevent asymmetric buildings from experiencing ductility demands much larger than those of the corresponding
torsionally balanced systems. Numerical analyses underline that while design procedures based on either static or modal analysis
are suitable for the design of torsionally rigid structures only those based on modal analysis lead to the satisfactory performance
of torsionally flexible buildings. Furthermore, the study highlights the qualities of a design method proposed by the Authors.
Its application does not require any explicit calculation of design eccentricities and leads to proper seismic response of
both torsionally rigid and flexible asymmetric buildings. 相似文献
302.
Four real buildings with three to six stories, strong irregularities in plan and little engineered earthquake resistance are subjected to inelastic response‐history analyses under 56 bidirectional EC8‐spectra‐compatible motions. The average chord rotation demand at each member end over the 56 response‐history analyses is compared to the chord rotation from elastic static analysis with inverted triangular lateral forces or modal response spectrum analysis. The storey‐average inelastic‐to‐elastic‐chord‐rotation‐ratio was found fairly constant in all stories, except when static elastic analysis is applied to buildings with large higher mode effects. Except for such buildings, static elastic analysis gives more uniform ratios of inelastic chord rotations to elastic ones within and among stories than modal response spectrum analysis, but generally lower than 1.0. With increasing EPA the building‐average inelastic‐to‐elastic‐chord‐rotation‐ratio decreases but scatter in the results increases. Static elastic analysis tends to overestimate the inelastic torsional effects at the flexible or central part of the torsionally flexible buildings and underestimate them at their stiff side. Modal response spectrum analysis tends to overestimate the inelastic torsional effects at the stiff or central part of the torsionally stiff buildings and underestimate them at the flexible side. Overall, for multistorey RC buildings that typically have fundamental periods in the velocity‐sensitive part of the spectrum, elastic modal response spectrum analysis with 5% damping gives on average unbiased and fairly accurate estimates of member inelastic chord rotations. If higher modes are not significant, elastic static analysis in general overestimates inelastic chord rotations of such buildings, even when torsional effects are present. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
303.
针对道路化简产生的与建筑物空间关系不一致问题,以道路与建筑物要素的关联关系为出发点,构建道路的目标移位安全区,在此基础上对D-P化简算法进行改善,提出一种以道路目标移位安全区为约束的D-P化简优化算法,在化简道路曲线的同时保证化简后道路曲线不与邻近建筑物产生空间冲突。选取1:10 000的建筑物与道路数据对多种目标比例尺的化简操作进行实验,结果表明该方法可有效保持道路与建筑物间的空间关系。 相似文献
304.
305.
This paper introduces the eigenspace structural identification technique for tall buildings subjected to ambient excitations that are stationary and where only the response time histories are measured. Based on the forward innovation model of the Kalman filter sequence, the actual response can be constructed as a function of the measured response time history with contamination of either displacement or velocity. The response time history is decomposed into subspace matrices using QR decomposition and Quotient Singular Value Decomposition (QSVD) techniques. These are then substituted into the least-square formulation to obtain the solution which is non-unique. Similarity transformation is applied to arrive at the desired solution employing the fact that eigenvalues of self-similar systems are identical. The advantages of this eigenspace technique are that it is non-iterative, initial estimates of the parameters to the identified are not required, well-established numerical algorithm of the decomposition techniques employed are available, and the method can handle MDOF systems efficiently. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
306.
Makola M. Abdullah 《地震工程与结构动力学》1999,28(2):127-141
The dynamic responses of tall civil structures due to earthquakes are very important to the civil engineer. These dynamic responses can produce situations that can range from uncomfortable to unsafe for the building occupants. In recent years classical control theory has been used in civil engineering to reduce the dynamic responses of tall civil structures. Most optimal control algorithms for civil structures involve full state feedback control which requires good estimates of the velocity and displacements throughout the structure. However, there are several important advantages of output feedback control: it takes less computational effort and it has the robustness of passive systems. In this paper, optimal control algorithms are formulated for the optimization of feedback gains and controller placement for building structures. The fundamental basis for these algorithms is the calculation of the gradient of the performance function with respect to the gain matrix. The effectiveness of the algorithm is demonstrated for deterministic earthquake loads in the time domain. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
307.
The aseismic capacity of a typical Korean wooden house built using traditional construction methods is quantitatively estimated. Tenon joints were used in wooden frames. Two 1:4 scale models were tested for rock and soil foundation conditions. Scaled real earthquake time histories were input for the tests. The natural frequency and modal damping ratio of the wooden house in the elastic range were 1·66 Hz and 7 per cent, respectively. The Peak Ground Acceleration (PGA) at the collapse of the house at the soil site was 0·25g, whereas PGA for moderate damage at the rock site was 0·6g. A significant reduction in acceleration response and increase in displacement response was observed for rock and soil foundation conditions, respectively. The wooden house studied is much more vulnerable at soil sites than at rock sites due to the rich low-frequency contents of the input motion and the flexible characteristics of the wooden house. Non-linear dynamic analyses using the modified Double-Target model were compared with test results. The modified Double-Target model appropriately simulates the non-linear inelastic behaviour of a wooden house with tenon joints. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
308.
The optimum parameters of tuned mass dampers (TMD) that result in considerable reduction in the response of structures to seismic loading are presented. The criterion used to obtain the optimum parameters is to select, for a given mass ratio, the frequency (tuning) and damping ratios that would result in equal and large modal damping in the first two modes of vibration. The parameters are used to compute the response of several single and multi-degree-of-freedom structures with TMDs to different earthquake excitations. The results indicate that the use of the proposed parameters reduces the displacement and acceleration responses significantly. The method can also be used in vibration control of tall buildings using the so-called ‘mega-substructure configuration’, where substructures serve as vibration absorbers for the main structure. It is shown that by selecting the optimum TMD parameters as proposed in this paper, significant reduction in the response of tall buildings can be achieved. © 1997 John Wiley & Sons, Ltd. 相似文献
309.
310.