中英桥规关于钢筋混凝土简支T形梁的设计比较

以钢筋混凝土简支T形梁桥主梁设计为例,从设计方法、结构安全系数、材料设计强度、荷载作用效应、截面配筋设计、裂缝宽度和挠度以及构造规定等方面,对我国现行的公路桥梁设计规范与英国BS5400规范进行了全面比较。结果表明,与我国规范相比,英国BS5400规范规定的结构安全系数总体上相对较高;两国规范采用的材料分项系数基本相同,但英国BS5400规范采用的钢筋强度设计值明显高于我国规范取值;此外,按英国BS5400规范计算的主梁荷载作用效应也明显大于按我国规范计算的结果;我国规范对混凝土裂缝宽度及主梁跨中挠度的控制要求比英国BS5400规范的控制要求更为严格。     

津湾广场9#楼超限高层结构抗震性能设计

津湾广场9#楼建筑总高度299m,为框架-核心筒结构,属超限高层建筑。介绍了工程的特点和结构设计情况,针对结构高度超限和竖向抗侧力构件不连续,采用了基于性能的抗震设计;并对结构进行多模型、多软件及弹性和弹塑性分析以及局部的补充验算,在宏观上把握结构薄弱部位,有针对性地采取加强措施。计算结果表明,结构的工作状态和性能均能达到设计的预期性能目标和规范要求。     

浅谈城市钢质燃气管道气压试验方法

分析了《城镇燃气输配工程施工及验收规范》和《城镇燃气室内工程施工与质量验收规范》对气压试验规定的适用范围,归纳了按两种规范进行气压试验时需注意的一些问题,从而为城市钢质燃气管道气压试验积累相关经验。     

带状法图斑编号的实现

提出按带状法进行图斑编号,真正实现图斑编号的从上到下,从左到右,方便图斑的查找和使用。     

智慧城市云平台构建研究

分析了国内智慧城市建设存在的问题,提出了智慧城市云平台的构架,论述了智慧城市云平台建设目标、实施步骤及建设运营模式,剖析了智慧城市云平台的产业链。     

Methodology for development of live load models for refined analysis of short and medium-span highway bridges

Abstract

The accuracy of bridge system safety evaluations and reliability assessments obtained through refined structural and finite element analyses depends not only on the accuracy of the structural model itself but also on the proper modelling of the maximum traffic loads. While current code-specified live load models were calibrated to properly reflect the safety levels of bridge structures analysed using the simplified methods adopted in bridge design and evaluation manuals, these load models may not lead to accurate results when implemented during refined structural analysis procedures. This paper describes a method to calibrate appropriate live load models that can be used for advanced analyses of bridges. The calibration procedure is demonstrated using actual traffic data collected at a representative weigh-in-motion station in New York State. The proposed calibration methodology is applicable for developing live load models for different bridge service periods, bridge types and design/assessment codes or standards. Live load models obtained using the proposed calibration procedure are readily implementable for deterministic refined analyses of highway bridges to produce similar results to those of complex traffic load simulations. Examples are presented that describe how results of such calibrated live load models would be used in engineering practice.     

‘Baltimore does not condone profiteering in squalor’: the Baltimore Plan and the problem of housing-code enforcement in an American city

In 1941, the Baltimore City Council passed a law, the Ordinance on the Hygiene of Housing, declaring that all property in the city should be ‘maintained in good repair by the owner or agent, and fit for human habitation’. The campaign of housing-code enforcement that followed, known as the Baltimore Plan, made the city famous. When historians write about American housing-reform efforts during the mid-20th century, they tend to focus on big-ticket federal policies; by contrast, the Baltimore Plan seems too small to be significant. But it is more than a curiosity. First in Baltimore and then across the country, the neat cause-and-effect it posited between good stewardship and good housing crowded out more challenging ways of thinking about the problem. Eventually, the Baltimore Plan turned into a policy tool that reinforced the interests of the real estate industry at the expense of poor people. In that regard, the Baltimore Plan laid the foundations for federal disinvestment in the provision of decent housing and the midcentury tragedy of urban renewal.     

Seismic design requirements for reinforced concrete piers considering aftershock-induced seismic hazard

The main purpose of this study is to develop an estimation procedure of seismic design level setting for reinforced concrete (RC) piers considering aftershock-induced seismic hazards. This work develops an assessment method of the seismic hazards induced by aftershocks and takes an example of the Chi–Chi Earthquake in Taiwan. The number of aftershocks is assumed to follow the modified Gutenberg–Richter law with lower and upper bounds when analysing the cumulative density function of the magnitude of the aftershock within a specified post-mainshock period for the earthquake. Additionally, this work considers the spatial uncertainty in the hypocentres of aftershocks to assess the aftershock-induced seismic hazards. Fragility curves and residual factors of damaged RC piers are used in the transition probability matrix of Markov Chain model for considering the cumulative damage induced by aftershocks by incorporating uncertainty into aftershock events, as well as into structural capacity and residual factors corresponding to a specified damage state, the exceedance probabilities for various damage states can be estimated using Markov Chain model and Monte Carlo Simulation. Finally, in the case study, the proposed procedure is used to determine the important factor in the preliminary seismic design of typical RC piers for the Chi–Chi Earthquake in Taiwan.     

大直径钢管桩竖向承载力计算方法研究

随着海上油气资源的深度开发与海上风电工程的投资建设,大直径钢管桩基础以其结构简单、安装便利、承载性能优越的独特优势被广泛使用。随着钢管桩直径的增加,其承载模式有别于传统的小直径桩。分析了太沙基、梅耶霍夫、别列柴策夫深基础承载力理论公式与建筑桩基技术规范、港口工程桩基规范、API、DNV规范以及考虑土拱效应的计算方法之间的差异性,并应用上述方法计算了实际工程中大直径钢管桩的竖向承载力,将计算结果与动测结果进行对比。结果表明:理论算法中太沙基法与梅耶霍夫法计算值较大,别列柴策夫公式和考虑土拱效应计算法相对准确;建筑桩基技术规范、港口工程桩基规范相对于API、DNV规范更加保守。     

浅析大中型建筑防火规范的若干条文

近年来,大中型建筑迅速发展。规模庞大、分区复杂以及设备繁多等各种因素,使大中型建筑的防火设计遇到了许多新的难题。本文针对建筑设计防火规范防中的若干条款,提出了自己的一些看法及应对措施,希望能为提高防火规范的合理性和科学性提供思路。