Jindřich Melcher

Design characteristics of structural steels based on statistical analysis of metallurgical products

Abstract The results of experimental research of material and geometrical characteristics of Czech steel are given in the present paper. The yield strength, tensile strength and ductility were evaluated statistically. For hot-rolled steel IPE profiles, the geometrical characteristics of cross-section dimensions were evaluated statistically too. It has been proved that both material and geometrical characteristics of plates and hot-rolled IPE profiles are satisfactory. The problems are discussed also in connection with application of stochastic computations. For this purpose, correlation coefficients among the quantities measured were also investigated.

ON SOME PROBLEMS OF ANALYTICAL AND PROBABILITY APPROACHES TO STRUCTURAL DESIGN

Publisher Summary This chapter deals with topical problems of improvement of structural design procedures by probabilistic approaches based on elaboration and evaluation of real measured data on strength and geometric characteristics of steel products. Traditionally, the design development process is characterized through progressive transition from the analysis of ideal member incorporated into the ideal structure towards the analysis of actual members with initial imperfections embodied into the real structural system. Nevertheless, nowadays, the essential advancement in structural design development proceeds from progressive transition, away from the deterministic understanding of structural system behavior,, towards the statistic and probabilistic approaches to structural reliability, considering the random distribution of action and resistance characteristics. The reliability-based approach to structural analysis presents an efficient instrument for calibration and verification of practically used design criteria. The chapter deals with general classification of material characteristics and presents examples of real product data and their distribution. Some questions of probability evaluation of design procedures are discussed through selected illustrative examples of reliability studies, namely the necessity of complex parallel study of both the action and resistance parameters in the specified design criterion. The chapter illustrates the general ideas and detailed examples of the probability approaches to steel structural design.

Shape and size of initial geometrical imperfections of structural glass members

Abstract In this paper measuring and determining of initial geometrical imperfections of set of glass members are presented. Measured specimens had the different dimensions and different composition – monolithic glass or laminated glass using different types of interlayer foils and glass panes. The shape of initial overall bow was measured using different methods and results were statistically evaluated and compared with allowable values defined in standards.

Experimental Verification of the Structural Glass Beam-Columns Strength

This paper deals with experimental research of axially and laterally loaded members made of structural (laminated) glass. The purpose of the research is the evaluation of buckling strength and actual behaviour of the beam-columns due to absence of standards for design of glass load-bearing structures. The experimental research follows the previous one focusing on measuring of initial geometrical imperfections of glass members, testing of glass beams and columns. Within the frame of the research 9 specimens were tested. All of them were of the same geometry (length 2000 mm, width 200 mm and thickness 16 mm) but different composition – laminated double glass made of annealed glass or fully tempered glass panes bonded together by PVB or EVASAFE foil. Specimens were at first loaded by axial force and then by constantly increasing bending moment up to failure. During testing lateral deflections, vertical deflection and normal stresses at mid-span were measured. A maximum load achieved during testing has been adopted as flexural-lateral-torsional buckling strength. The results of experiments were statistically evaluated according to the European standard for design of structures EN 1990, appendix D. There are significant differences between specimens made of annealed glass or fully tempered glass. Differences between specimens loaded by axial forces 1 kN and 2 kN are negligible. The next step was to determine the design strength by calculation procedure based on buckling curves approach intended for design of steel columns and develop interaction criterion for glass beams-columns.

Stability of Thin-Walled Beams with Lateral Continuous Restraint

Abstract Metal beams of thin-walled cross-sections have been widely used in building industry as members of load-bearing structures. Their resistance is usually limited by lateral torsional buckling. It can be increased in case a beam is laterally supported by members of cladding or ceiling construction. The paper deals with possibilities of determination of critical load of thin-walled beams with lateral continuous restraint which is crucial for beam buckling resistance assessment

NUMERICAL ANALYSIS OF BEHAVIOUR OF COMPRESSION MEMBERS MADE OF LAMINATED STRUCTURAL GLASS

Abstract This paper deals with design of compression members made of monolithic and laminated structural glass. Glass columns are analysed by numerical models using RFEM and ANSYS software with consideration of variable value of the interlayer shear modulus. Obtained elastic critical forces, stresses and deflections are compared with the values from the analytical calculation according to the second order theory.

GEOMETRICALLY NONLINEAR NUMERICAL ANALYSIS OF BEAMS OF MONOSYMMETRIC THIN-WALLED CROSS-SECTIONS LOADED PERPENDICULARLY TO THE PLANE OF SYMMETRY

Abstract The paper deals with geometrically nonlinear analysis of steel beams of monosymmetric thinwalled cross-sections loaded perpendicularly to the plane of symmetry eccentrically to the crosssection shear centre. Numerical analysis of selected transversely loaded beams is performed using Dlubal RFEM code based on finite element method. Accuracy of interaction formula for bending with lateral torsional buckling and torsion is studied.

Two studies on the actual behaviour and limit states of steel structures

Publisher Summary The chapter discusses two studies on the actual behavior and limit states of a steel structure. It studies two groups of problems, one of them being carried out in Prague and the other one in Bmo, Czech Republic, a successful solution of which can significantly help to promote headway in the design of progressive and effective steel structural systems. One of the studies, the related research being conducted at the Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences in Prague, is predominantly concentrated on the limit states of thin-walled plated structures. The chapter reports about a large number of tests which have to be performed in order to look into the cumulative damage process that is generated in steel plate girders whose slender webs “breathe” under many times repeated loading.

Deliberation on safety concepts applied in design procedures of steel structures

Publisher Summary The chapter discusses problems of linking between structural analysis and design code procedures, especially from the point of view of semi-probability and probability approaches that, in general, lead to more transparent understanding of the reliability of structural members. Deliberation on safety concepts, applied in design procedures of steel structures, focuses on problems of complex set and combined effect of components that significantly influences the specified reliability. The chapter provides an example that illustrates how the resulting reliability of compression member varies depending on the arrangement of partial safety factors in design criterion and on predominant loading type in loading combination, considering the statistical distribution of material and geometrical properties of structural element. It is shown that for the variable ratio of permanent to variable action, the member reliability of both the allowable stress design concept and the limit state concept is, in general, not steady and well-balanced, and the partial safety factors in design criterion should be calibrated and verified.