Calculation of guyed masts in accordance with EN 1993-3-1 standard taking into account mast shaft geometrical imperfections

Selected problems concerning designing of guyed masts with lattice shaft in accordance with the “EN 1993-3-1: Design of steel structures. Part 3-1: Towers, masts and chimneys-Towers and masts” European standard have been described in this paper. The method of application of the mast shaft geometrical imperfections in calculations has been discussed. Based on the performed comparative analysis of a certain mast, the influence of such imperfections on the ultimate values of internal forces in the mast shaft has been demonstrated.     

Analyses of distortional buckling of cold-formed sigma purlins using EN1993-1-3

This technical note presents a study on the calculation of the critical stress of distortional buckling of cold-formed sigma purlins using EN1993-1-3. The discussion is focussed on the determination of the spring stiffness of the stiffened element, a problem which has not yet been addressed in most design codes. Different support conditions at both the tension and compression ends of the web are employed and their influences on the critical stress of distortional buckling of sigma purlins are investigated. Comparison with finite strip analysis indicates that the model having a fixed support for the tension end and a roller support for the compression end of the web provides the best fit to the finite strip analysis.     

欧洲钢结构新规范EN1993-1-1对压弯构件计算的新规定

在新的欧洲钢结构规范EN1993—1—1即将颁布使用之际,本文就规范中压弯杆的计算的新的规定加以说明,解释新规定的来源、背景资料,探讨简化的相关公式。新规定的最主要的发展在于弯扭失稳公式中的相关系数以及稳定系数。本部分工作是基于欧洲钢结构协会(ECCS)第8技术委员会(TC8)的工作成果,新成果更加先进及经济。     

GB/T 13754与EN 442-2及试验台重复性比较

比较了国家标准GB/T13754—2008《采暖散热器散热量测定方法》与欧洲标准EN442-2-1997《辐射器和对流器—第二部分:测试方法和等级评定》在试验装置、测试工况、散热器散热量的修正方法方面的区别。对根据国家标准建立的散热器试验台(测试小室采用风冷夹层)与根据欧洲标准建立的散热器试验台(测试小室采用水冷夹层)的重复性进行了比较,后者的重复性较好。     

焊接工艺评定标准ASME Ⅸ与EN ISO 15614-1的对比分析

针对锅炉、压力容器焊接工艺评定用ASMEⅨ和EN ISO 15614-1标准的差异和特点进行了对比分析。通过对这些标准适用范围、焊接试件、检测项目和焊接工艺评定的代用范围等方面的分析,认为:ASMEⅨ适用范围更广,焊接工艺评定的认可范围较大,而EN ISO 15614-1要求的检测项目更多、焊接工艺评定的认可范围相对较窄。目前,国内的锅炉、压力容器制造企业更加熟悉ASME标准,但随着欧洲业务的不断拓展,对EN ISO 15614-1标准的理解和掌握就变得越来越重要。     

Establishing stress state of cylindrical metal silos using finite element method: Comparison with ENV 1993

There is at present a great deal of interest in developing new methods and calculation tools for use in the study and measurement of stress states in shell metal structures. The finite element method (FEM) is a numerical method which permits this kind of study, and which is put forward in the European experimental standard, ENV 1993, as an accurate and reliable calculation tool. This study presents different three-dimensional models whose distinguishing feature is the simulation of both stored granular material and silo walls, without resorting to simplifications. The models developed predict the stress state of cylindrical metal silos flat bottomed, subjected to the action of stored granular material in their interior. The behaviour assigned to the stored material is elastic, and that assigned to the structure is the classical bilinear elastic-perfectly plastic, typical of metallic materials such as steel. Two geometric parameters are analysed: height and thickness of the wall. The results obtained from numerical methods (hoop, meridional or vertical, normal and shear stresses) are compared with those obtained via ENV 1993-1-6.     

钢结构抗火的计算及措施

介绍了火灾下钢结构内部温度场计算、钢结构抗火的设计方法,并总结了钢结构抗火的措施、防火涂料的选用与施工要求,为钢结构抗火设计积累了经验,对钢结构抗火性能的进一步研究具有重要的意义。     

Aeroelastic divergence and flutter: Critical comments on the regulations of EN 1991-1-4

The European wind-load standard EN 1991-1-4 (2010) contains regulations that deal with aeroelastic instabilities of structures. These are discussed and commented on in this article. Numerical calculations are used to corroborate the comments. It is shown that some of the regulations do evidently not provide generally applicable criteria to avoid aerolastic instabilities. On the basis of the statements made in this article, a modified text is proposed for the standard. A numerical example serves to explain the regulations regarding aeroelastic divergence.     

CASS与HTCAD的土方计算比较

在工程建设中,经常要进行场地整平或改造成设计坡度的斜面,由此产生的土方量大小与工程投资直接相关,因此准确、快速地计算土方量对开展规划设计、控制总投资及分配资金具有重要意义。本文分析比较了两种常用土方计算软件,用相对成熟精确的方格网法,对同一块场地进行土方计算,比较两者的操作性、运算速度和精度,分析其相对优缺点。     

Effects of heat sinks on evolution of longitudinal temperature distributions in steel structures

Evolution of longitudinal temperature distributions along steel frame components during fire is an inherent thermodynamic behavior, stemming from differences in the properties of columns and beams, and from heat sinks above and below the fire-room. Despite early literature clearly indicating that these may affect structural response, the phenomenon has not been investigated. This paper presents analysis of partial effects of heat sinks on longitudinal temperature distributions by means of an advanced non-linear numerical model. It includes representative results and trends of temperatures and influence-distance versus some main geometric factors affecting the longitudinal distribution. Results indicated that these factors are the values of virtual thickness, the column-to-beam ratios, and a combined factor of cross-sectional area and virtual thickness ratio to which joint temperature is highly correlated. A simplified lumped-mass linear model, applied preliminarily to evaluate the order of magnitude of temperature reduction in the vicinity of the joint, is appended.     

GB16410与EN30灶具热效率测试方法对比

介绍了GB16410--2007及EN30—2—1：1998中灶具热效率的测试和计算方法,分析了测试及计算方法的不同对结果的影响：     

Sources of elastic deformation in steel frame and framed-tube structures: Part 1: Simplified subassemblage models

Three simple models for including the effect of beam-column joint deformation in the analysis of steel moment resisting frame and framed tube structures are presented. The first model, called the Fictitious Joint model, is based on two-dimensional frame analysis and is useful for preliminary analysis only. The second model, called the Krawinkler Joint model, and the third model, known as the Scissors Joint model, use an assembly of rigid links and rotational springs to represent the joint, and may be used in preliminary and final analysis of full structural systems. All derivations are provided in the form of “displacement participation factors”, which allow a detailed breakdown of the various components of subassemblage displacement.When applied to isolated beam-column subassemblages, it is shown that all three modeling approaches produce the same general expression for computing deflections arising from shear deformations in the panel zone region. However, the Krawinkler and Scissors models do not include the effects of flexural deformation within the beam-column joint, whereas the Fictitious Joint model does. While not the dominant source of deformation, it is shown in the paper that the effects of flexural deformations in the beam-column joint should not be ignored.It is also shown in this paper that the overall displacements predicted by the simplified models correlate very well with displacements computed from detailed three dimensional finite element analysis of the same subassemblage. However, the finite element analysis approach, taken alone, is not capable of providing a breakdown of the subassemblage displacements into components, such as panel zone shear, or column joint flexure. Part 2 of the paper presents a method for providing this information from the results of detailed finite element analysis.     

Sources of elastic deformations in steel frame and framed-tube structures: Part 2: Detailed subassemblage models

This paper examines the accuracy of a set of equations for computing Displacement Participation Factors (DPFs) for beam-column subassemblages of steel moment resisting frame buildings. These factors allow the analyst to determine how the entire subassemblage or individual components of a subassemblage contribute to a given structural displacement. Additionally, the component’s contribution to displacement may be evaluated in terms of sources of axial, flexural, or shear deformation.When applied to a set of 12 isolated subassemblages, it was shown in Part 1 of the paper that deformations in the beam-column joint are very significant, and that flexural deformation in the joint, which is often ignored, should be considered in all analyses. The total displacement predicted through the use of the DPFs correlates extremely well with the results of detailed three dimensional finite element analyses of the same subassemblages. However, it was also shown that there is considerable uncertainty in the bending moments and moments of inertia that are used to compute joint flexural deformations.The objective of this paper, which is the second part of a two-part paper, is to further investigate the accuracy of the DPF expressions developed in Part 1. This is done by computing DPFs from the results of detailed three dimensional finite element analysis, and comparing these to those computed through the use of the simple expressions.The results of the analysis show that the joint flexural deformations are accurately predicted by the simple DPF expressions, but that this accuracy arises from compensating “errors” in the simplified analysis. It is also shown that the use of beam flange continuity plates has a marginal effect on computed displacements. The paper ends with recommendations for using the simplified expressions for computing subassemblage deformations, and for including such deformations in structural analysis of steel frame and tube structures.     

高速公路钢结构纪念碑既有结构检测鉴定分析

以大运高速公路雁门关纪念碑为例,根据该纪念碑的形式,利用全站仪、超声波测厚仪、高精度涂层测厚仪等常用检测仪器,对该结构强度、耐久性进行检测鉴定,为类似的钢结构纪念碑鉴定分析提供参考。     

钢柱温度应力数值计算与试验对比研究

联合应用恒载升温热—力路径下所得ε—T—k材料模型与恒温加栽热—力路径下所得ε—k—T材料模型,构建了一种与受火钢构件实际热-力路径相符的分段叠加计算模型,并将计算结果与试验结果进行对比分析.结果表明:所采用分段叠加法突破了传统的恒温加载试验和恒载升温试验钢构件热-力路径,计算所得结果与试验结果相近,作为计算分析钢构件温度应力的一种方法,可有效提高钢结构抗火设计与评估的准确性.     

公路与城市桥梁设计规范的抗震计算比较

根据《公路工程抗震规范》、《公路桥梁抗震设计细则》、《城市桥梁抗震设计规范》,比较了某立交桥梁的抗震验算过程,并分析了公路抗震规范与城市抗震规范的差异。分析结果表明,在E1地震作用下,公路与城市抗震规范计算差异主要由反应谱的计算差异引起;在E2地震作用下,两者之间的差异主要由对塑性状态时混凝土承载能力贡献的取值不同引起。