内撑式预应力撑杆柱的稳定承载能力试验研究

采用预应力撑杆柱是提高细长型钢柱稳定承载能力的有效方法。本文在分析预应力撑杆柱受力特点的基础上,结合南京图书馆新馆的工程实际,对5根内撑式预应力撑杆柱进行了稳定承载能力模型试验研究,并进行了2根细长形方钢管柱和3根方钢管混凝土柱的模型试验作为对比。重点研究了不同长细比、不同柱截面形式、不同支座约束条件的预应力撑杆柱的稳定承载力。本文的试验与分析结果表明,只要设计合理,内撑式预应力撑杆柱与同尺寸的钢管柱相比具有更高的稳定承载能力,是一种安全、可靠、美观的结构构件。文章还对背景工程内撑式预应力撑杆柱的设计和施工提出了参考建议。     

Behavior of prestressed stayed steel columns under fire conditions

Prestressed stayed steel columns experience loss of strength and stiffness when exposed to fire conditions. This paper presents results from experimental studies on the behavior of prestressed stayed circular steel columns under fire conditions. Two full scale prestressed stayed steel columns were tested by subjecting the columns to simultaneous gravity (mechanical) loading and fire conditions. In these fire tests, the varied parameters include load level and level of prestressing. Cross sectional temperatures, axial deformations, as well as fire resistance during the fire tests were recorded and measured. The results indicate that prestressed stayed steel columns undergo various failures modes under different combinations of load and prestress ratios. Specifically, load level significantly influence the fire response of prestressed stayed steel columns with higher load level leading to higher contraction and lower fire resistance.     

预应力轴压撑杆钢柱高温性能试验研究与数值分析

为研究预应力轴压撑杆钢柱的高温性能，进行了2根预应力撑杆钢柱高温试验。试验结果表明：拉索无防火措施时，其相对张力在初始升温阶段就迅速下降，直至完全松弛；预应力撑杆钢柱的轴向变形先由于热膨胀效应轴向伸长，而后在压力作用下轴向压缩；临界状态时，撑杆柱出现对称和反对称两种失稳形态。采用验证后的ANSYS有限元分析模型，考虑材料非线性、几何非线性和初始缺陷等，分析了荷载比、相对轴向刚度比和预应力比等3个关键参数对预应力撑杆柱高温性能的影响，得到了一系列拉索相对张力、侧向变形和轴向变形分别与时间的关系曲线。分析表明：预应力撑杆柱中拉索张力很快在高温下逐渐松弛，达到张力松弛所需时间主要受预应力比影响；预应力撑杆钢柱的侧向变形在升温初期缓慢增长，在失效前增长迅速；随着荷载比增大，预应力撑杆柱侧向变形和轴向变形越来越明显，且达到峰值所需时间不断缩短；预应力比对撑杆钢柱失效临界温度影响较小，但对预应力撑杆柱的破坏形态有较大影响。     

Experimental study of critical and post-buckling behaviour of prestressed stayed columns

A full scale experimental investigation into the strength and behaviour of prestressed steel stayed columns in compression has been conducted. Results, including full load versus end-shortening curves, for a total of 18 test specimens are presented. Two critical modes of buckling — symmetric and antisymmetric — with interactive post-buckling are demonstrated experimentally and the imperfection sensitivity of the stayed columns is investigated. Interactive buckling is observed primarily when the individual buckling loads of the antisymmetric and symmetric modes are close or when the antisymmetric mode is critical. Analysis of the results reveals that increased prestress leads to an increased load-carrying capacity when instability occurs in the symmetric mode, but the reverse trend is found when the antisymmetric mode is critical.     

广东现代国际展览中心结构设计

本文介绍了广东现代国际展览中心结构设计。重点论述该结构体系的计算模型处理、基础选型以及大跨度预应力空间网架和局部二层大跨度预应力钢筋混凝土楼盖结构体系的优化设计,得到一些有意义的结论。本结构设计的主要特点是:(1)上部预应力网架结构通过两侧的拉杆锚在桩上而形成一个自平衡体系,从而减小支承结构柱的弯矩和剪力;(2)钢柱柱脚铰接的选择对于优化结构受力非常关键;(3)通过在钢柱沿建筑长方向上设置预应力拉索来保证钢柱在该方向上的稳定性。     

绥芬河青云集团地下商场屋盖的合理选型与设计

介绍了绥芬河青云集团地下商场的基本概况,针对其柱网尺寸和所承受的荷载均较大这一客观事实,设计了无粘结预应力混凝土无梁楼盖和无粘结预应力混凝土井式梁板楼盖两种结构方案。介绍了这两种方案的设计要点及造价分析。可供设计建造同类工程时参考。     

Der Viadukt über das Tarntal bei Millau – Von den ersten Entwurfsgedanken bis zur Fertigstellung

The viaduct over the Tarn valley near Millau – from early design to completion. The erection of the viaduct over the Tarn valley near Millau in central France began in October 2001 and was completed in December 2004. The viaduct with an overall length of 2460 m covers six 342 m long main fields, those at seven suspension towers is embodied and represents an important progress in design of cable‐stayed bridges. The motorway runs in 270 m height over the river, two of their columns are more highly than 230 m. Together with the 87 m high pylons over the roadway towers are higher then the Eiffel tower in Paris. Two solutions were prepared, one in prestressed concrete and one in steel construction method.     

预应力CFRP布加固负载混凝土柱轴心受压性能研究

为开展轴心压力作用下预应力碳纤维增强复合材料（CFRP）布加固负载圆形截面混凝土短柱力学性能研究,设计制作了11根圆形截面混凝土短柱,其中1根普通混凝土柱为对比柱,其余10根混凝土柱在负载与非负载2种情况下分别利用预应力CFRP布或非预应力CFRP布进行加固。通过轴心加载试验,获得了各试件极限荷载、轴向变形、材料应力变化等试验数据。基于试验数据分析了试件轴心压力作用下的力学性能。结果表明:与普通混凝土柱相比,利用预应力CFRP布加固的负载混凝土柱在二次受力过程中其屈服荷载有显著提高,且提高幅度与CFRP布预应力水平成正比,但极限承载力与CFRP布的预应力水平无关;利用预应力CFRP布加固的负载混凝土柱延性性能有显著提高。     

Die Geh‐ und Radwegbrücke Kehl – Strasbourg

The Pedestrian and Cycle Bridge Kehl – Strasbourg. The Rhine bridge between Kehl and Strasbourg is the new regional landmark and linking element of the International Gardening Show. The approach to unifying different functions and an architectural endeavour lead to a unique structural system. Two separate decks address the different situations on the river banks and, linked by a platform, form a balcony above the Rhine at midspan. The main bridge is a cable‐stayed structure with a steel pylon and a steel‐concrete composite deck. The approach bridges are continuous girders on steel columns. Both pile and flat foundations are featured in the design. The article describes the structural concept and design, outlines the erection procedure and discusses aspects of the dynamic behaviour of the bridge.     

大跨度预应力住宅结构体系最大适用高度研究

按现行规范及异形柱结构技术规程,设计了两栋大跨度预应力异形柱住宅结构,并采用基于柔度法的纤维模型梁柱单元计算了在不同水准地震作用下结构的响应。采用异形柱轴压比、结构弹性最大层间位移、构件截面抗震设计、结构弹塑性最大层间位移四个指标,综合考虑设计、施工及造价等因素确定了该结构体系的最大适用高度,为该结构体系设计指南的编制提供了参考依据。     

预应力大跨度空间钢结构的应用与展望

本文主要阐述了我国预应力大跨度空间钢结构应用与发展的基本情况。这些顶应力空间钢结构包括有预应力网络结构、斜拉网络结构、张弦梁结构、弓式预应力钢结构等。最后,本文展望了新世纪的预应力空间结构。     

北京南银大厦结构设计

北京南银大厦是一栋多功能高层建筑。根据工程场地情况,基础采用预应力混凝土管桩,计算沉降量满足要求。上部抗侧力体系采用框架-筒体结构,采取相应的措施,解决了框架布置不规则、柱距大等工程设计中的难点。结构计算分析结果表明,变形和承载力都满足要求。结构上部设置3层钢框架,介绍了结构的主要技术与构造措施和钢框架的设计情况。     

预应力钢板箍加固RC柱轴压性能试验研究

进行了5个采用预应力钢板箍加固的RC柱试件和1个未加固RC柱对比试件的单调加载试验,重点研究预应力钢板箍加固RC柱的轴压性能和加固构件轴压承载力计算方法。试验主要参数包括钢板箍预应力水平和钢板箍配箍特征值。试验结果表明：采用预应力钢板箍加固RC柱可显著改善其轴压性能,不仅可有效提高柱的轴压承载力,还能使加固柱具有较好的变形能力。在试验研究基础上探讨了预应力钢板箍加固RC轴压柱受力机理,分析了各主要参数对加固柱轴压承载力的影响。分析结果表明：预应力钢板箍强度发挥系数与钢板箍预应力水平和钢板箍配箍特征值等因素有关。采用叠加方法,提出加固柱轴压承载力计算式,计算结果和试验结果总体吻合良好。     

An Object-Oriented Diagnostic System for Prestressed Concrete Bridges

Abstract: A prototype knowledge-based diagnostic system for understanding the problems in prestressed concrete bridges is presented. The object-oriented approach is used for the system development. The system is completely interactive, making extensive use of pictures and diagrams along with textual explanation to explain difficult concepts in a multilingual environment. The system compares the new case of damage with the various types of damages that are stored in the knowledge base. It explains to the user the details of design and construction that may lead to this damage and the related repair methods. The system indicates the applicability of textual and pictorial explanations in developing an environment for the diagnosis of problems in prestressed concrete bridges.     

Post-buckling behaviour and direct strength design of lipped channel columns experiencing local/distortional interaction

This paper reports an investigation aimed at developing a Direct Strength Method (DSM) approach to estimate the ultimate strength of lipped channel columns affected by local/distortional buckling mode interaction. Following a brief presentation of a few relevant aspects concerning the shell finite element analysis of the geometrically and materially non-linear behaviour of thin-walled members, one illustrates the methodology adopted to obtain a lipped channel column ultimate load “data bank” intended to be used in the development and assessment of a DSM design approach. Next, the current DSM expressions to predict the load-carrying capacity of columns failing in local and distortional modes are briefly reviewed, devoting special attention to an approach that takes into account the above mode interaction. Then, the results of a parametric study, carried out by means of the code Abaqus, are presented and discussed — this study involves the evaluation of the “exact” ultimate loads of 276 lipped channel columns with various geometries and two boundary conditions (pinned and fixed end supports), all exhibiting local/distortional interaction. Finally, these ultimate strength data are compared with the estimates provided by the available DSM expressions and, on the basis of this comparison, one identifies several features that a DSM approach successfully accounting for local/distortional interaction must incorporate.     

局部/畸变屈曲相互作用下卷边槽钢柱的后屈曲性能及直接强度设计

对直接强度法(DSM)进行改进,以计算局部/畸变屈曲相互作用下卷边槽钢柱的极限强度。首先,采用壳体有限元分析方法分析薄壁构件的几何特性和材料的非线性特性,并简单描述该分析过程的主要内容。利用该方法建立卷边槽钢柱的极限荷载"数据库",以用于改进和评估DSM设计方法。其次,简要回顾了当前计算局部和畸变作用下柱破坏时承重能力的DSM表达式,特别是考虑局部和畸变交互作用的方法。此外,研究了两种边界条件下(铰接和固接)局部/畸变屈曲相互作用下几何尺寸不同的276根卷边槽钢柱的极限荷载,给出ABAQUS软件的参数研究结果,并对其进行了讨论。最后,将这些极限强度数据与DSM计算结果进行比较,结果表明,采用DSM计算局部/畸变屈曲交互作用时需考虑某些特性。     

强震区单跨36m预应力框架设计与分析

海南省体育中心综合训练馆为单跨36m预应力框架及屋盖网架的三层混合结构.为解决单跨结构抗震问题,在建筑两端设置抗震墙作为主要抗侧力结构;为解决大跨边柱的大偏心受压问题,在边框架柱中设置斜向预应力筋,并通过设置牛腿增大预应力筋偏心距及解决柱张拉端问题.该文对强震区的大跨预应力梁柱设计,尤其是预应力柱的计算分析方法具有较大...     

Multi-objective reliability-based optimization of prestressed concrete beams

A general approach to the multiobjective reliability-based optimum (MORBO) designs of prestressed concrete beams (PCB) is presented in this paper. The proposed approach incorporates all behavior and side constraints specified by the American Concrete Institute (ACI) code for prestressed concrete. Loading, material properties, prestressing force and the models used to predict structural performance at various stages—initial, final and ultimate—are all treated as random variables. A general MORBO methodology is solved by integrating PCB design and reliability analysis computer programs with an automated design optimization package. Only bi- and tri- multiobjective (MO) formulations, subjected to eleven reliability constraints and four geometrical constraints, are considered. The competing objectives in the multiobjective optimization of PCB are selected from, minimization of the overall cost of the PCB, maximization of the system reliability index, maximization of the flexural strength reliability index, and maximization of the tensile stress reliability index at service stage. The design variables consist of six geometrical dimensions that shape the PCB cross section and one that represents the amount of prestressing steel. Numerical examples illustrate the application of the proposed approach to the MORBO of PCB are presented. The -constraint (trade-off) approach is used for the solution of the MORBO.     

南京长江二桥南汊桥斜拉索塔节段足尺模型的研究

斜拉索塔的拉索锚固区是斜拉桥的关键部位,其受力相当复杂,一般的平面分析很难反映实际的应力分布.本文简要介绍了南京长江第二大桥首次采用在箱型截面内布设小半径大吨位的环向U型预应力体系的斜拉索塔节段足尺模型试验研究的主要方案、方法,给出了在预加应力阶段及混凝土开裂前索塔节段足尺模型的试验测试值和有限元空间分析值,结果表明吻合较好.文中还在最后给出了模型结构的开裂荷载和极限荷载,并对设计提出了若干建议.