Wirtschaftliche Bemessung von Druckstäben aus gewalzten I‐Profilen mit dem Kappa‐Verfahren

Economical design of compression members with hot‐rolled I‐sections by use of the κ‐method. The main focus of the article is on the evaluation of κ ‐values for compression members with hot‐rolled I‐sections. Based on numerically determined κ‐values the accuracy is reviewed and existing reserves are pointed out. In order to utilize this reserves besides the indication of the exact κ‐values a new buckling curve ab is recommended. The curve allows for typical column sections with h/b ≤ 1,2, so for structural application especially interesting cases, a more economical design as up to now.     

Residual stress analysis of structural stainless steel sections

The magnitude and distribution of residual stresses in structural carbon steel sections have been thoroughly investigated. However, few residual stress measurements have been made on structural stainless steel sections. Stainless steel has differing material stress-strain characteristics and thermal properties to carbon steel, both of which influence the formation of residual stresses. This suggests that established carbon steel residual stress models may not be appropriate for stainless steel. With increased use of stainless steel in load bearing applications, it is important to establish the residual stresses that exist within structural members. An experimental program to quantify the residual stresses in stainless steel sections from three different production routes has therefore been carried out. Comprehensive residual stress distributions have been obtained for three hot rolled angles, eight press braked angles and seven cold rolled box sections, with a total of over 800 readings taken. This paper presents the experimental techniques implemented and the residual stress distributions obtained as well as discussing the assumptions commonly made regarding through thickness residual stress variations. In the hot rolled and press braked sections, residual stresses were typically found to be below 20% of the material 0.2% proof stress, though for the cold rolled box sections, whilst membrane residual stresses were relatively low, bending residual stresses were found to be between 40% and 70% of the material 0.2% proof stress.     

Kranbahnträger aus warmgewalzten Mannesmann‐Stahlhohlprofilen (MSH)

Crane runway made of hot‐rolled Mannesmann steel hollow sections (MSH). A new crane runway over a couryard on the production site of Vallourec & Mannesmann Deutschland GmbH in Düsseldorf, Germany should be realised using quadratic hot‐rolled hollow sections. For this purpose a new design was to be developed and realised. Until now crane runways for large spans and high loads have been built using box girders or individual designed special solutions. The production of these girders as well as the erection on site is complex and expensively in terms of time and costs. On the basis of a close collaboration of all involved project partners and under the leadership of Dittmann & Pollmann, Hagen, Germany the technical challenge was mastered and a new type of crane runway was realised.     

Erforderliche Einspanntiefe von Stahlstützen in Betonfundamenten

Required length of restraint for steel columns in concrete foundations. Steel columns are connected frequently bending resistant to concrete substructures. With this type of construction the required length of restraint must be specified and the load‐carrying capacity of the steel columns within the range of the concrete foundations has to be verified. In the report consistent load‐carrying models are presented, which are considering the ultimate plastic load‐carrying capacity of cross sections and new calculation models according to Eurocode 3 for locals verifications. The verification conditions are formulated for steel columns made of rolled and welded I‐sections, which are stressed by one‐ or two‐axial bending with compression normal force. For columns with rolled sections calculation adds are given, which makes it possible to read off directly the required length of restraint.     

Evaluation of creep and shrinkage effects in composite tall buildings

In a composite tall building, adjacent vertical members undergo differential time‐dependent deformations due to creep and shrinkage. Highly elaborate, complex and requiring large computational effort procedure, utilizing stress transfer method, age‐adjusted effective modulus method (AEMM) is available to evaluate creep and shrinkage effects in a composite building. Recently, a simple procedure and requiring lesser computational effort, utilizing AEMM has been presented for concrete and composite buildings. Studies comparing deflections and axial forces in reinforced concrete frames with those obtained from the procedure available in literature (using stress transfer method, RCM) have been reported. In this paper, suitability of the above procedures for evaluation of creep and shrinkage effects in composite buildings has been demonstrated. Studies are reported for typical creep shrinkage parameters. It is shown that the error to determine axial forces from AP(AEMM) is small for composite frame–shear wall systems with very low beam stiffness (I_b = I_c/100). Use of CP(AEMM) is warranted for the frame–shear wall systems even with low beam stiffness (I_b = I_c/20). Copyright © 2010 John Wiley & Sons, Ltd.     

Considerations on the value of the reduction factor for lateral-torsional buckling of beams in bending

The paper presents a new formula for the reduction factor for lateral-torsional buckling χ_LT of beams in bending. The proposed formula covers satisfactorily a large number of experimental results, which are presented in the Background Document 5·03 to Eurocode 3, and refers to 144 rolled sections and 71 welded sections. The formula eliminates the jump of the χ_LT factor in the case of .     

Torsions‐Querschnittswerte für rechteckige Hohlprofile nach EN 10210‐2:2006 und EN 10219‐2:2006

The new European Standards EN 10210‐2:2006 and EN 10219‐2:2006 contain the necessary cross‐section values for calculation of primary torsion (St. Venant‐torsion). In the following paper all cross‐section values for secondary torsion are additionally given, so that calculation of normal and shear stresses of the warping torsion is possible. These stresses cannot be neglected, but occur only at certain points of disturbance. For hollow sections it is always necess‐ary to take into consideration the shear deformations of warping torsion.     

Bed shear stress evaluation in combined sewers

Experiments have been undertaken on two sewer trunk lines in order to identify an accurate and practical technique for estimating bed shear stresses in combined sewers. Various methods were tested to determine both local bed shear stress values (one based on the logarithmic velocity profile and the other on the Reynolds shear stress distribution) and mean bed shear stress values (using a method based on the energy slope). Velocity measurements were performed using a micropropeller and an Acoustic Doppler Velocimeter (ADV) under dry weather flow conditions. In sewers without sediments, both the wall law and Reynolds shear stress distribution methods lead to the same bed shear stress estimation. A method based on the logarithmic velocity profile obtained by micropropeller is proposed herein to evaluate local shear stress in combined sewers. Calculations based on channel slope lead to an over-estimation of bed shear stress due to the inaccuracy of bed slope data. If the energy slope S _c , as calculated from the Darcy-Weisbach or Manning formula, is used to calculate the mean shear stress in sewer sections without sediments, results are consistent with the local shear stress measurements.     

Torsionsträgheitsmoment und Schubmittelpunkt von Winkelprofilen

Torsional cross‐section properties for angles. Using the finite element method (FEM) it is possible to determine accurate torsional cross‐section properties for hot rolled angle‐profiles. These values partly show relative big discrepancies to the approximations used in practice. For this reason the accurate position of the shear centre as well as the St. Venant's torsion constant for the profiles of DIN EN 10056‐1 are specified. In addition the knowledge of these values can be used to improve familiar approximations and to develop new formulae for the torsional constant.     

地震场地的综合评定方法

本文给出了一个考虑场地土层的刚度、覆盖土层厚度及软弱夹层、液化土层等因素对场地地震动影响的综合评定方法。该方法根据场地土层的刚度和覆盖土层的厚度，按模糊评判方法确定场地指数μ值，并建立μ值与设计地震反应谱的关系。当场地指数确定时，就可确定用于抗震设计的反应谱。对于场地土层中含有软弱夹层或液化土层的情况，本文还给出了考虑这些影响因素，对场地指数或设计地震动参数进行修正的方法。     

Wölbkrafttorsion von Durchlaufträgern mit konstantem Querschnitt unter Berücksichtigung sekundärer Schubverformungen

Warping torsion of continuous beam with constant cross‐section considering shear deformation. The analogy between the theory of warping torsion and second order theory of a bending member with tensile force is also valid, if shear‐deformations in both cases are additionally included. On the basis of this analogy the three‐moment equation for continuous beam with constant cross‐section is given. It is demonstrated, that shear‐deformations for open sections can normally be neglected but must be encluded in the case of hollow‐sections. It is also shown, that for these sections warping‐torsion occurs only in ranges of discontinuity, but causes stresses which are in the same order as the stresses of primary torsion.     

Experimental investigation of residual stresses in roller bent wide flange steel sections

Residual stresses in straight hot rolled wide flange sections are well documented and have been investigated in the recent past. However, to the knowledge of the authors, residual stress measurements have not been published on roller bent wide flange sections. Straight sections are curved into roller bent ones at ambient temperatures by means of the roller bending process. Since roller bent sections underwent severe plastic deformation during the forming process, the well-known residual stress patterns from hot rolling may not be appropriate for the roller bent steel. Roller bent sections can be applied in halls, roofings and bridges, thereby acting as structural arches and it is important that a realistic residual stress pattern is implemented when assessing their load carrying capacity. An experimental program has been carried out to investigate the residual stresses in roller bent wide flange sections bent about the strong axis. Residual stresses were measured with the sectioning method. The experimental technique was investigated with respect to possible temperature influence and repeatability of the measurements. Experimental values revealed that the residual stress pattern and magnitude in roller bent sections is different when compared to their straight counterparts.     

Bügelbemessung nach DIN 1045‐1 mit Berücksichtigung von Längskräften

Design of stirrups in accordance with DIN 1045‐1 taking into consideration longitudinal forces. Traction (n_Ed > 0) increases the required stirrups for shear only, compression (n_Ed < 0) reduces these. The presented diagrams enable a clear, rapid determination of the stirrup ratio ρ_w for shear and longitudinal forces.     

Fracture toughness study for a brittle rock subjected to mixed mode I/II loading

A semi-disk specimen containing an angled edge crack has been used in the past for conducting fracture tests on a brittle rock named Johnstone [Fracture testing of a soft rock with semi-circular specimens under three-point bending. Part 2—mixed mode. Int J Rock Mech Min Sci Geomech Abstr 1994b;31(3):199–212]. The test specimen is appropriate for investigating brittle fracture when the rock samples are subjected to the combined effects of tension and shear along the crack line. However, the experimental results reported in Lim, Johnston, Choi, Boland [Fracture testing of a soft rock with semi-circular specimens under three-point bending. Part 2—mixed mode. Int J Rock Mech Min Sci Geomech Abstr 1994b;31(3):199–212.] are inconsistent with all of the well-known theoretical criteria available for predicting mixed mode brittle fracture. In this paper, a modified criterion is used to provide accurate predictions for the reported experimental results. The modified criterion makes use of a three-parameter model (based on K_I, K_II and T) for describing the crack tip stresses. It is shown that the non-singular stress term T has a significant role when the rock fracture tests are conducted on the semi-disk specimens.     

Influence of cold bending on the resistance of wide flange members

Cold rolling is used for bending straight members with hot rolled wide-flange sections to create arches. Extensive studies have shown that the influence of residual stresses due to hot rolling on the resistance of wide-flange steel sections is nonnegligible. On the contrary, the residual stress pattern due to roller bending has been only recently identified. Its effects on the elasto-plastic behavior of curved members have not been studied sufficiently. In this paper, an in-depth study of the influence of such residual stresses is performed. Considering the residual stress pattern due to cold bending, interaction diagrams and buckling curves for cold bent steel arches are developed. The results are quantified and compared with those for hot-rolled and stress free members. This allows designers to appreciate the available margins of safety when using standard interaction equations and buckling curves for cold bent members. Furthermore, the results suggest the necessity for the development of buckling curves for cold bent members including initial imperfections.     

Zum Tragverhalten von Verbunddübeln – Teil 1: Tragverhalten unter statischer Belastung

Verbunddübel stellen eine sehr tragfähige und robuste Verbindung auch bei hochfesten Betonen zwischen Stahlbauteilen und Betonquerschnitten dar. Die Herstellung des Stahldübels ist dabei einfach und wirtschaftlich. Mittels Verbunddübelleisten lassen sich neue Querschnitte für den konstruktiven Ingenieurbau entwickeln. Halbierte Walzprofile, die mit der speziellen Geometrie der Verbunddübel geschnitten wurden, werden als außenliegende Bewehrung im Verbundbau eingesetzt. In zwei Teilaufsätzen wird die Bemessung der Verbunddübel für unterschiedliche Randbedingungen und Belastungsarten erläutert. Der erste Beitrag befasst sich mit der Technologie der Verbunddübel, deren Tragverhalten und der Bemessung der Verbindung unter ruhender Belastung. Das Ermüdungsverhalten ist Schwerpunkt in einem zweiten Aufsatz. Die Problemstellung wird ausführlich erläutert und ein Bemessungsvorschlag auf Grundlage des Strukturspannungskonzeptes vorgestellt. Load bearing behaviour of composite dowels – Static loads (part I). Composite dowels realise a high load bearing capacity for connections between concrete and steel. The technology establishes a short time and cost‐effective production process. Using composite dowels for shear transmission new and innovative cross‐sections can be designed. Halved rolled sections which have been cut along with a specific dowel geometry are applied as external reinforcement. The publication is divided into two parts describing design of composite dowels for different boundary conditions and load cases. Foremost the technology, their load bearing behaviour, the design concepts for composite dowels for static loads are highlighted. The behaviour under cyclic load, will be introduced in a second part. The fatigue behaviour will be explained in detail and design concepts based upon the hot spot stress will be given.     

Buckling analysis of buildings braced by frameworks,shear walls and cores

A simple hand method is presented for the three‐dimensional stability analysis of buildings braced by frameworks, coupled shear walls, shear walls and cores. Sway buckling behaviour is characterized by three types of deformation: the full‐height ‘local’ bending of the individual columns, wall sections, shear walls and cores, the full‐height ‘global’ bending of the frameworks and coupled shear walls, which is associated with the axial deformations of the column and wall sections, and the shear deformation of the frameworks and coupled shear walls. Based on the stiffnesses associated with these three types of deformation, a closed formula is derived for the calculation of the sway critical load. An analogy between bending and torsion is used to carry out the pure torsional buckling analysis. The interaction between the bending and shear modes as well as among the basic buckling modes (sway in the principal directions and torsion) are taken into account. A worked example with step‐by‐step instructions shows the easy use of the method. The results of a comprehensive accuracy analysis involving 73 multistorey buildings are also given together with comparisons with other analytical methods. Copyright © 2002 John Wiley & Sons, Ltd.     

Bestimmung der Wölbspannungen von doppeltsymmetrischen Kastenquerschnitten mit Diagrammen

Determination of warping stresses of box sections by diagrams. For determination of warping torsion for beams with box section it is sufficient to examine only points with external torsional moments. Moreover in the case of statically indeterminate systems the reaction torsional moments may be calculated neglecting warping torsion completely. This contribution allows the determination of normal and shear stresses of warping torsion by diagrams or alternatively by formulae depending only of two parameters of the section. Warping moment and secondary torsional moment must then not be calculated. The applied theory encludes secondary shear deformation, which is always necessary in the case of hollow sections.     

Beitrag zur Ermüdungsfestigkeit von Schienenschweißnähten bei Kranbahnen

Contribution to characteristic fatigue strength of rail welds at crane runways. The rail welds of today's crane runways usually made of hot rolled sections for light and moderate crane service form one important critical detail of the wheel load application in terms of fatigue. The characteristic fatigue strengths and the definition of damage accumulation under combined loading of the national and European design codes are compared and critically discussed. Moreover, an overview of the few, available test data of large‐scale specimens on the fatigue behaviour under wheel load application is given, and own girder tests are presented.     

Shear lag analysis of I‐shaped structural members

I‐shaped structural members are widely used in civil engineering, mainly including I‐shaped shear walls and beams. In order to establish a unified method for analyzing the shear lag effect of I‐shaped structural members, first, the shear lag warping displacement is assumed as a quadratic parabola, and the additional deflection caused by shear lag effect is taken as the generalized displacement. The principle of minimum potential energy is used to establish the calculation method of the normal stress and deflection of I‐shaped shear walls and beams with 3 boundaries, which consider the self‐balancing conditions of shear lag warping stress. Then numerical examples are used to verify the accuracy of the calculation method; meanwhile, the shear lag characteristics of I‐shaped structural members are investigated. At last, the calculation method is used to study the shear lag effect of T‐shaped structural members. Studies show that the analytical results obtained by the calculation method are close to the finite element method results, and the calculation method can predict the flange normal stresses and negative shear lag phenomenon well. Moreover, the calculation method in this paper can be used to analyze the shear lag of T‐shaped structural members.