共查询到20条相似文献，搜索用时 31 毫秒
1.
针对上海市超限高层建筑工程实例,收集整理了相关设计信息,构建了能够表征这些设计信息的数据表并形成了数据库。鉴于传统的管理信息系统不能够空间表示,提出了一种新型的基于Arc-GIS的信息系统,同时引入了贝叶斯网络,以数据库样本为基础进行结构选型。实践证明,该系统充分利用了计算机的存贮、计算、统计、共享以及空间显示功能,贝叶斯网络为超限高层建筑结构体型优选提供了一种新的方法,对超限高层建筑工程的设计改进和规范的完善都具有一定的实际意义。 相似文献
2.
从20世纪90年代起,研究人员就开始探索活动断层探察数据的制作、存储与管理。迄今为止,已经获得了大量的活动断层探察数据,建成了一套系统的数据组织体系,为减轻地震灾害的相关研究提供了数据和技术支撑。近年来,随着活动断层数据库信息的扩充,初期设计的部分属性信息编码已不适用。为了形成适应当前工作的属性信息编码体系,本文以活动断层数据库建设体系为基础,对数据库属性值代码进行信息分类和编码优化。文章将数据库属性值代码分为字符型单一含义值、数值型单一含义值及复合含义值,分别进行编码规则设计,最终优化了数据库属性信息编码体系,提高了从建库到数据应用的数据录入、检测、制图自动化、数据分析等环节的效率。 相似文献
3.
4.
L. Sanchez-Ricart 《Bulletin of Earthquake Engineering》2011,9(5):1579-1592
A computer program is developed to test the influence of the structural overstrength to calibrate seismic codes. The program
automatically performs an iterative design-evaluation process to calibrate the seismic code. A numerical example is performed
in order to test the different approaches. The virtual simulation shows that the force reduction factor cannot be directly
deduced from building performance in past earthquakes. This custom of deducing the force reduction factor from the building
performance under past earthquakes artificially increases the ratios elastic spectrum to design spectrum due to the design
structural overstrength. The similitude of the simulation with the historical calibration of the design spectrum in the seismic
codes in the United States of America (USA) is evident. 相似文献
5.
CT图象重建的算法优化和代码优化 总被引：4，自引：1，他引：3
卷积反投影是CT图象重建的最重要算法作为一种线性处理,其基本算法并不复杂,但由于CT的数据量庞大,使得图象重建的计算十分耗时.国外CT大都采用基于64位CPU的工作站并配以专门为CT建象设计的阵列处理板,这种昂贵的造价数十万元的计算机系统对一般医院用户来说是很大的经济负担.相反我们一直采用通用PC工作站,不仅降低了成本,而且计算机可以得到迅速的升级.这样,为满足医院临床诊断和治疗对建象速度的需要,我们就必须对该算法进行优化,优化的效果也成为CT软件能否适应市场需要,能否最终产品化的关键.本文总结了针对CT图象重建分别在算法层次和代码层次上所做的优化工作.第一,在算法实现的层次上,(1)在反投影算法中,进行内外循环交换,将最内层循环的计算量最大限度地减少,(2)利用反投影算法的对称性,只计算出部分图象数据并对称得到其它图象数据,(3)根据不同的视野范围自动调整反投影的计算量,(4)充分利用FFT的特点,提高实数线性卷积的效率.(5)数据的行列交换,用于提高CPU对数据的存取速度.第二,在代码编程的层次上,充分利用新一代微机CPU--Pentium III提供的新资源、新指令和相应的代码优化工具软件,重新编写算法关键部分的程序代码,以提高程序的实际执行效率.在东大阿尔派全身CT扫描机CT-C2000上的实际测试表明,通过上述算法优化和代码优化,CT图象重建软件的运行速度提高了8倍以上,己达到了医院实际使用的要求. 相似文献
6.
In this paper a probabilistic approach has been adopted to study both the effects of uncertainty in earthquake frequency content and the correlation between earthquake frequency content and ground motion intensity on the response of a single-storey torsionally coupled elastic structure. The earthquake ground motion has been assumed to be a Gaussian, zero mean, stationary random process which is fully characterized by a power spectrum. The ground acceleration power spectrum is idealized as a probabilistic normalized power spectrum computed from actual earthquake records. The advantage of such an idealization is that it enables the effect of the natural frequency as a controlling structural parameter in torsional coupling to be assessed. Comparisons of the dynamic amplifications of eccentricity with those obtained from modern codes of practice and conventional response spectrum analyses have been made. The results of this study have shown that the variation in the frequency content has a significant effect on the response of low frequency structures, while the correlation between the frequency content and the intensity of seismic ground motion is insignificant for the wide range of structures considered. The structure natural frequency has been shown to be an important controlling parameter in the torsionally coupled response of structures subject to seismic loading. The frequency dependence of the dynamic amplification of eccentricity was found not to be reflected in the response spectrum analysis and the torsional provisions of modern building codes. 相似文献
7.
随着重力和重力梯度测量技术的日趋成熟,基于重力和重力梯度数据的反演技术得到了广泛关注.针对反演多解性严重、计算效率低和内存消耗大等难点问题,本文开展了三维重力和重力梯度数据的联合反演研究,该方法结合重力和重力梯度两种数据,将L0范数正则化项加入到目标函数中,并在数据空间下采用改进的共轭梯度算法求解反演最优化问题.同时,本文摒弃了依赖先验信息的深度加权函数,引入了自适应模型积分灵敏度矩阵,用来克服因重力和重力梯度数据核函数随深度增加而衰减引起的趋肤效应问题.为了提高反演计算效率,本文又推导出基于规则网格化的重力和重力梯度快速正演计算方法.模拟试算表明,改进的共轭梯度法可以降低反演的迭代次数,提高反演的收敛速度;自适应模型积分灵敏度矩阵,可以有效解决趋肤效应,提高反演纵向分辨能力;数据空间和改进的共轭梯度算法结合,可以更好地降低反演求解方程的维度,避免存储灵敏度矩阵,有效地降低反演计算时间和内存消耗量.野外实例表明,该算法可以在普通计算机下快速地获得地下密度分布模型,表现出较强的稳定性和适用性. 相似文献
8.
9.
抗震设计规范中的场地设计反应谱是一般工程抗震设计的依据,各国的抗震设计规范对场地设计反应谱的规定不尽相同。主要表现在反应谱的形状和谱参数的差异。本文收集了若干国家的抗震设计规范;在总结各国抗震设计规范中关于场地设计反应谱规定的基础上,对中国、美国、日本、欧洲、土耳其和智利等有代表性的国家和地区的抗震设计规范进行分析和对比研究;总结了我国抗震设计规范场地设计反应谱的演化历史和发展过程;提出了进一步开展这一领域研究工作的若干建议,本文的工作对从事场地设计反应谱研究的科技人员有重要的参考价值。 相似文献
10.
抗震规范应用强度折减系数的现状及分析 总被引：5，自引：1，他引：4
世界上大多数的抗震规范都采用了基于强度的设计方法,强度折减系数是基于强度的抗震设计中确定设计地震力的关键因素,提高强度折减系数的可靠性已经被认为是提高现有抗震规范可靠性的有效途径。本文主要介绍了抗震研究处于世界先进水平的美国(UBC97)、欧洲(EC8)、日本、墨西哥、加拿大、中国等国家抗震规范中强度折减系数取值的有关规定,然后给出了各国学者关于规范规定的强度折减系数的一些重要讨论和分析,最后指出了世界各国应用强度折减系数过程中存在的不足,指出了需进一步研究的问题。 相似文献
11.
To simplify the analysis of soil–structure interaction systems, various fixed-base models have recently been proposed by the author to efficiently represent the SSI system and have been shown to have good accuracy. However, the modified mass and damping matrices of these models do not hold the properties of symmetry and orthogonality. Difficulties may consequently be induced for these models in applying conventional computer codes to carry out dynamic analysis. In the present paper, this problem is further explored to establish a fixed-base model possessing classical normal modes. Formulated in the modal space, this fixed-base model is constructed through applying an iteration algorithm to incorporate the Gram–Schmidt orthogonalization process. The convergent real orthogonal mode vectors, natural frequencies, and modal damping ratios are directly determined for this model. It is demonstrated with a numerical example that this new fixed-base model retains excellent accuracy. Accordingly, the complicated SSI systems can be directly analyzed using conventional computer codes for structural dynamics with the fixed-base model developed in this study. 相似文献
12.
F. Pergalani R. Romeo L. Luzi V. Petrini A. Pugliese T. San 《Soil Dynamics and Earthquake Engineering》1999,18(4):978
The earthquake of 26 September 1997 in Central Italy is one of the largest seismic events of the last 20 years in Italy. Two main events that caused significant damage in a large area of Umbria and Marche regions and site amplification phenomena were recorded even at large distances from the epicenter. After the emergency period, a detailed study of the surface effects was necessary for the post-earthquake reconstruction, but in a way it should be carried out rapidly enough to allow urban planners to give instructions and codes to public administrators. A team of surveyors were trained to collect field information such as geologic and geomorphologic features and, where possible, pre-existing geotechnic or geophysic information. Information was collected and analyzed with the aid of dynamic codes to calculate the possible local site effects. A one-dimensional code, analyzing single soil columns,
[Schabel PB, Lysmer J, Seed HB.
, a computer program for earthquake response analysis of horizontally layered sites. College of Engineering, University of California, Berkeley, Report PB-220. 1972, p. 207], as well as the two-dimensional codes working with finite or boundary elements,
[Idriss IM, Lysmer J, Hwang R, Seed HB.
, a computer program for evaluating the seismic response of the soil structure by variable damping finite element procedures. UCB EERC Report No. 73-16. 1973.] and
[Sanò T.
, un programma per il calcolo della propagazione delle onde sismiche. Technical Report SSN/RT/96/9. 1996, pp. 51.], were used and the results are presented as response spectra or amplification coefficients. 相似文献
13.
14.
按新旧规范设计的多层住宅砖房地震易损性的对比 总被引：1，自引：0，他引：1
本文采用概率方法借助于拉丁超立方采样技术和非线性地震反应时程分析对按现行规范设计的多层住宅砖房的地震易损性进行分析,并与按上一代规范设计的多层住宅砖房的地震易损性分析结果[1]进行了比较,为进一步研究这类结构的地震安全性、未来地震的损失预测以及防震减灾对策奠定基础。 相似文献
15.
量子遗传算法（QGA）以量子理论为基础,通过利用量子位编码代替经典遗传算法的二进制位编码,利用量子旋转门定向更新种群来代替传统方法中种群的选择、交叉和变异过程,使得算法具有一定的内在并行运算能力和量子的隧道效应,从而加快了搜索速度,改善了收敛速度,并具有更强的全局寻优能力.本文针对地球物理反演问题的非线性、多极值特点提出一套实现方案,通过理论模型和实测数据试验对比研究,表明量子遗传方法在大地电磁反演中的寻优质量和效果明显优于传统遗传算法. 相似文献
16.
17.
18.
The use of certain codes for the Vibroseis system of exploration has been investigated. The codes considered are well-known in communication theory. The effect of coding the Vibroseis input signal is the suppression of correlation noise and therefore an improvement of the signal to noise ratio. It is believed that, during the course of research, a new property of one of the codes used has been discovered. 相似文献
19.
在地震来临时,一般假设建筑结构同时受到两个正交水平方向分量与一个竖向分量的地震动作用。双向水平地震效应组合方法用于估计两个正交水平分量地震动同时作用时结构的内力效应。本文主要对我国与美国抗震设计规范中规定使用的平方和开平方根（SRSS）方法与百分比组合方法的有效性进行了评估。首先,对比了我国与美国规范在考虑双向水平地震效应时的适用情况及相关规定上的异同。以一4层中心支撑-框架结构为工程案例,考虑两国规范在适用情况上的规定,设置了三个结构布置方案。对三个结构布置方案建立有限元模型,选取22组地震动,开展了动力时程分析。提出了针对SRSS方法与百分比组合方法的评估指标,基于时程分析结果,发展了双向水平地震效应组合的概率性评估方法。评估结果表明:SRSS方法与百分比组合方法用于平面扭转不规则结构的设计较为保守。在简化组合规则的适用条件上,美国规范对平面扭转不规则结构不进行考虑有一定的合理性。建议我国规范对中心支撑-框架结构中含双向受压柱的设计要求考虑双向水平地震效应组合。 相似文献
20.
Displacement capacity of masonry piers: parametric numerical analyses versus international building codes 总被引：1，自引：1，他引：0
Maurizio Orlando Luca Salvatori Paolo Spinelli Mario De Stefano 《Bulletin of Earthquake Engineering》2016,14(8):2259-2271
The nonlinear behaviour of masonry piers loaded in their plane is investigated by parametric numerical simulations. Each pier has a cantilever scheme, is loaded by a constant axial load and is subjected to an increasing horizontal displacement at the top. The macro-modelling approach is used to perform numerical analyses, adopting two different constitutive laws: a total strain crack model and a plastic model. The numerical model is calibrated on a block-masonry type for which experimental tests are available in literature. Parametric numerical simulations are performed by varying the aspect-ratio and the compression level, in order to assess the influence of such parameters on both shear strength and displacement capacity. By comparing numerical results with formulas of international codes, a good agreement for the shear strength is obtained, while significant differences are observed for the displacement capacity, which is influenced by both parameters. The authors propose a simple empirical formula for the displacement capacity, obtained by fitting the numerical results. The expression can be useful in the practical design for considering the influence of aspect-ratio and compression level, currently neglected by building codes. 相似文献