Ermüdungsverhalten von Mobilkranbauteilen aus hochfesten Baustählen

Fatigue behaviour of component sections of mobile cranes out of high strength steel plates. High‐strength structural steels with 960 and 1100 MPa minimum yield strength allow a decrease of the investment and operating costs of mobile cranes through lightweight design. However, there still exists an uncertainity for stress resistance under cyclic loads and bearable stresses concerning fatigue behaviour of important crane components. This paper deals for the first time with the fatigue behaviour of crane components examined under realistic load‐time‐cycles derived from realistic crane operating conditions. The results supply important information as they indicate that the service life for both steels, even with very high applied stress, is at least 20years. Moreover, it is shown that further improvements of the durability are possible around up to 50% through subsequent treatment of the welds, toughness improvement of the base material and constructive remodelling of the components. Additionally, this paper provides a new design method with which the fatigue behaviour of crane components under most different aspects and involved variable combinations can be estimated, consistent with measured values, through a fracture mechanically based model. Important procedure recommendations and hints can be given for a more intense use of high‐strength structural steels for practical application in mobile crane engineering. Inspection intervals and contents can be newly determined.     

某炼钢厂房钢吊车梁疲劳性能测试及分析

以某炼钢厂房吊车梁疲劳性能应力测试结果为例,结合有限元模拟,对钢吊车梁的疲劳性能进行分析。结果表明：钢吊车梁腹板截面突变处应力集中现象明显,构件疲劳性能严重;随着生产技术的进步,冶金工厂吊车运行频繁程度的大幅度提升,GB 50017—2003《钢结构设计规范》对欠载效应等效系数的取值较实际情况偏低,建议将炼钢厂房重级工...     

Untersuchungen zum Ermüdungsverhalten von Konstruktionsteilen für Mobilkrane

Fatigue behaviour of component sections of mobile cranes out of high strength steel plates. High‐strength structural steels with 960 and/or 1100 MPa minimum yield strength allow a decrease of the investment and operating costs of mobile cranes through lightweight design. However, there still exists an uncertainity for stress resistance under cyclic loads and bearable stresses concerning fatigue behaviour of important crane components. This paper deals for the first time with the fatigue behaviour of crane components examined under realistic load‐time‐cycles derived from realistic crane operating conditions. The results supply important information on the service life. The service life depends in this case strongly from the tension level considerably. The influence of the here applied load‐time‐cycles appears on the other hand small. Additionally, this paper provides a new tool with which the fatigue behaviour of crane components under most different aspects and involved variable combinations can be estimated, consistent with measured values, through a fracture mechanically based model. There can be made important procedure recommendations and hints can be given for a more intense use of high‐strength structural steels for practical application in mobile crane engineering. Inspection intervals and contents can be newly determined. The usage of steels with more than 1100 MPa minimum yield strength in the mobile crane building is evaluated crucially.     

钢结构吊车梁疲劳动态可靠度研究

本文视吊车荷载与疲劳强度为随机过程 ,建立了基于极限应力模式的钢结构吊车梁疲劳动态可靠度分析模型 ,提出了对吊车荷载效应与构件疲劳强度进行统计分析的方法。并结合某工程现场实测荷载数据与模型疲劳试验 ,对某工业厂房吊车梁圆弧端进行了疲劳可靠度评估 ,结果表明本文建立的疲劳动态可靠度分析模型能很好对吊车梁圆弧端的破坏情况进行概率解释。     

平台钢框架分离式柱的疲劳破坏

某依附于平台框架的分离式柱承受最大为450/80t重级工作制吊车荷载的作用,建成使用不到20年,有多根柱子在柱头处出现裂缝。现场应力测量和结构整体的计算分析表明,由于构造不合理,裂缝处存在较高的压应力和初始拉应力。在吊车荷载反复作用下,疲劳强度不足,因而出现疲劳破坏。考虑到出现裂缝后,初始应力会得到一定程度的释放,提出了简单的局部加固方案,并付诸实施。     

考虑吊车性能优化的钢结构优化设计

近年来，国内一些起重机厂家开发了性能优化的轻量系列吊车产品，其轮压值及小车重量较旧有系列吊车显减轻。当钢结构厂房应用此类吊车时。可较大幅度的降低吊车梁与刚架的用钢量。本介绍了按新旧系列不同参数计算吊车梁及门式刚架用铜量的结果比较及量化的规律分析，有助于铜结构设计中扩展思路与优化设计。     

波纹腹板焊接H形钢疲劳性能试验研究

设计了4根梯形波纹腹板焊接H形钢试件,依据GB 50017-2003《钢结构设计规范》的相关规定进行疲劳性能试验,并特别考虑了GB 50278-2010 《起重设备安装工程施工及验收规范》中吊车梁安装偏差的相关规定。通过ANSYS有限元分析验证试件破坏形式的合理性。研究结果表明：对于CECS 291:2011 《波纹腹板钢结构技术规程》中推荐波形的梯形波纹腹板H形钢,其疲劳性能优于平腹板H形钢,疲劳设计中可按3类钢构件进行计算,且不考虑腹板波纹转折引起的应力集中及安装偏差等施工因素的影响。     

Decision support system on IBM PC for design of economic steel structures applied to crane girders

A decision support system (DSS) was developed on a personal computer for the economic design of steel structures. The DSS contains six various-type single-criterion and seven multicriteria optimization methods. The economic design of the asymmetric main box girders of overhead travelling cranes was realized by considering four objective functions and sixteen nonlinear inequality constraints according to BS 2573 and BS 5400. Constraints on static and fatigue stress, on local buckling of flange and web plates, as well as on static deflection, are considered. Numerical computations show the effects of material, welding, surface preparation and total cost on each other. Use of higher strength steel may result in savings on the cost of materials, depending on the cost factor employed.     

太原湖滨广场超高层内爬外挂塔式起重机施工技术

太原湖滨广场主楼采用钢结构外框架-混凝土核心筒结构,高208m,在施工过程中采用2台大型内爬外挂塔式起重机。采用一套循环组合钢结构挂架将塔式起重机悬挂于核心筒的外壁,使塔式起重机随着核心筒的施工进度协调爬升。详细介绍了内爬外挂塔式起重机选型、附着方式、施工原理及挂架的加工制作、质量控制、挂架安装等施工工艺,解决了超高层建筑的垂直运输问题,提高了大型塔式起重机的使用效率,加快了施工进度。     

Instandsetzung und Verstärkung von Stahlbrücken mit Kategorie‐3‐Schäden

Reinforcing steel bridges with category 3 damages – report on a BASt research project. In recent years, fatigue damages have been observed at the main supporting structure of steel bridges, the orthotropic decks, as well as the transverse structure of steel bridges (the so‐called category 3‐failure). The rapidly increasing road traffic intensifies the situation resulting in a huge amount of steel bridges affected by fatigue damages. Existing steel bridges with category 3‐fatigue cracks have been intensively investigated. Fatigue failure modes and general evaluation criteria have been summarized, analysed and categorized, in order to enable first fundamental and time‐efficient definition and classification of category 3‐damages. FE‐simulations of transversal steel bridge structures (with and without reinforcements) have been carried out to evaluate and review the structural bridge concepts. Based on these studies, a special way of the steel bridges' maintenance has been followed up, which is removing all possible transversal bracings. Finally, different options of maintenance and repair have been investigated both newly and successfully applied in the recent past. Appropriate actions for solving essential category 3‐fatigue problems are presented.     

Fatigue life prediction of existing crane runway girders

In this study, fatigue life of crane runway girders of a steel mill structure was investigated. Load spectra were generated based on former crane operation records. Detailed finite element models of the crane runway girders were prepared using shell and beam elements. Quasi-static load tests were conducted with the help of overhead cranes that travelled with crawling speed. Strain data was collected by using transducers mounted on preselected locations of the crane runway girders. These data were then used to refine the finite element models. Numerical analyses by means of the calibrated finite element models were performed to evaluate the remaining fatigue life. It was found that due to lack of continuity of vertical stiffeners to upper flange, fatigue life of the crane girders is exceeded. To overcome this problem, fillet welding of the stiffeners to flanges is suggested and this modification is verified by carrying out necessary calculations for the updated detail.     

Erweiterung der DASt‐Richtlinie 009 für die Stahlgütewahl bei Einschubverbindungen im Hochbau

Extension of DASt‐RiL 009 for the choice of steel quality for welded connections of bracing components in building constructions. DASt‐Richtlinie 009, equivalent to DIN EN 1993‐1‐10, provides a tool based on fracture mechanics for the choice of material of steel structures to avoid brittle fracture at low temperatures. The procedure has initially been developed for the conditions of bridges, i.e. for fatigue loading and is applicable for all structural details for which fatigue classes are determined in DIN EN 1993‐1‐9 or in DIN‐Fachbericht 103. For such structural details the procedure can also be applied for buildings on the safe side. Economic connections in building frames, e.g. welded connections of bracing components in slotted gusset plates are normally designed with plastic resistance models ignoring any notch effect relevant for fatigue. Therefore they are not in the scope of DASt‐RiL 009. This contribution gives a proposal for an extension of DASt‐RiL 009, such that it covers these types of connections in building frames as well. The procedure of determining tables for the selection of steel qualities is as for bridges, except that the assumptions for the assessment (e.g. crack sizes) are different. The simplified tables have the same format as table2 in DASt‐RiL 009, however the influence of plate thickness is smaller than that of other geometric parameters.     

Schweißen ermüdungsbeanspruchter Altstahlkonstruktionen – Untersuchungen zum Einfluss der Vorbelastung auf die Lebensdauer der Schweißkerbdetails

Welding of existing steel structures – Effect of prior load cycles. When existing structures under fatigue load are to be strengthened or refurbished by welded joints fatigue assessment is required for new welds. For the analysis of existing structures or determining of their remaining fatigue life, experimental investigations were carried out in order to estimate the effect of prior load cycles on the material. Mild steel specimens were preloaded cyclically, then surface treatment was applied and a notch representative for a real weld of a structure was introduced. The results of fatigue tests were compared with fatigue tests on similar non‐preloaded specimens. It has been found that there is no significant effect of prior load cycles if the surface is treated prior to welding and enough fusion penetration depth is given. Therefore, fatigue assessment of new welds on old materials does not need to take into account prior load cycles.     

某重型钢结构厂房结构设计

针对某大型锻钢件厂房的结构设计,采用合理的方法判断吊车的组合情况,并手工计算吊车组合荷载工况,得出比较合理又满足结构设计安全要求的设计结果。通过设计分析,对如何合理优化此种类型钢结构厂房,如何避免设计易出现的问题进行介绍。     

铁路钢桥基于名义应力法的疲劳寿命预测研究

通过建立铁路疲劳列车模型,采用自编的影响线动态加载程序和三点雨流计数法程序对某64m钢桁梁桥不同部位杆件的应力谱进行了计算分析,并对其疲劳寿命预测进行了研究,得出了一些重要结论,可为铁路钢桥的疲劳寿命预测提供理论依据。     

Verbesserung der Ermüdungsfestigkeit höherfester Baustähle durch Anwendung der UIT‐Nachbehandlung

Enhancement of the fatigue strength of welded high strength steels by application of Ultrasonic Impact Treatment (UIT). According to the present state of the art welded high strength steels have the same fatigue strength as welded standard steels. For an effective application of high strength steels in constructions subjected to fatigue are therefore additional efforts necessary in order to improve the fatigue strength, for example by the application of post‐weld treatment methods. However up to the present it is not possible to apply the positive effects of these methods in the fatigue design of steel structures. Within this paper an experimental test program studying the effectiveness of the post‐weld treatment method “Ultrasonic Impact Treatment” (UIT) on the critical construction detail of the transverse stiffener is presented. The test program comprises small scale fatigue tests on the standard and high strength steel grades as well as full size girder fatigue tests. Based on experimental and numerical investigations recommendations for the fatigue design of welded structures treated by UIT are given.     

CCTV主楼大型动臂式塔式起重机高空移位安装

CCTV主楼塔楼双向倾斜,悬臂结构悬挑距离长.施工过程中需将内爬塔式起重机多台次移位安装.从主体钢结构工程、压型钢板工程、混凝土工程、核心筒的加同支撑等方面介绍了塔式起重机高空移位工况.重点阐述了M1280D塔式起重机高空移位超重部件摆放和拆装顺序,以及超长起重臂高空摆放部位选择和安全措施.     

FEM‐Untersuchung zur Beurteilung des Einflusses von geometrischen Imperfektionen auf die Lebensdauer von Schraubenverbindungen bei Windkraftanlagen

FEM‐Investigation to evaluate the influence of geometric imperfections on fatigue of preloaded bolt connections of Wind Energy Converters. There is a strong influence on fatigue of preloaded bolted ring flange connections with geometric imperfections, as they are used for tubular steel towers of wind turbines. This can result in fatigue failure of the connections because the bolts could not take the high dynamic loads sufficiently. This paper is dealing with the results of [1] in which the influence on fatigue of variing geometric imperfections at L‐flanges was investigated numerically. The results of this thesis paper lead to a gener criteria, which can be very useful in order to rate geometric imperfections, as they appear in production line. It should be used to sensitize manufactorers and quality responsible staff in reason of allowable tolerances in the assembly process of windturbine towers.     

复杂工况下多台汽车吊行走楼板加固支撑研究

青岛北客站站房结构形式复杂,钢结构构件超长且最大质量达121t。由于现场施工条件限制,B区钢结构吊装须采取2台240t汽车吊上楼板的方式进行施工。根据施工计算结果,采取钢管柱与脚手架支撑相结合的方式对B区楼板进行结构加固并提出针对性的质量控制措施。在施工过程中较好地完成了异型构件在多台汽车吊协同状况下的吊装作业,取得了良好经济效益。