Duško Lučić

Experimental research on I-girders subjected to eccentric patch loading

Abstract This paper presents the results of the experimental research performed on the thin-walled I-profiles subjected to patch loading. The experiment was divided into two phases. During the first one the behaviour of girders subjected to loading in the plane of the web was studied, and during the second phase, girders subjected to loading showing certain eccentricity in relation to the web plane were analysed. Thirty-six tests were performed. This paper analyses the results of girders under eccentric loading. The girders were tested to final collapse. The failure load is smaller under certain conditions than in cases with concentric load. Girder collapse form differs considerably from the collapse form of the concentrically loaded beams. Carrying capacity loss in the case of concentrically loaded girders is due to web buckling, while in the case of eccentrically loaded beams we consider the problem of carrying capacity loss due to local elasto-plastic bending. During the process of load increase the most evident deformation is flange warping accompanied by gentle web bending, which follows flange deformation. Flange warping and web bending grow until final collapse of girder. The most important question which is to be investigated in the future is under what conditions and what combinations of different parameters and eccentricity values the collapse form will be of the same kind as with concentrically loaded girders.

Experimental investigation on locally pressed I-beams subjected to eccentric patch loading

A review of experimental research performed on thin walled I girders subjected to patch loading is presented in this paper. Primarily, the aim of the research was to thoroughly in vestigate the behaviour of girders subjected to eccentric patch loading, i.e. loading out of the web plane. This experiment is connected to the previous experimental–theoretical research conducted at the Faculty of Civil Engineering, University of Montenegro, in the years of 1998 and 1999. Load was applied over the flange in increments until final girder collapse. Various web thicknesses were studied. Loading eccentricity was varied six times for each girder type. Altogether, there were 24 tests. Six of those tests were performed using strain gauges, so that some valuable information was gathered with respect to stress distribution and the formation of yielding lines over the girders. Previous experimental research showed that the collapse form of the girders under centric loading was different from the form of those loaded eccentrically. Now, it turns out that with small eccentricity, the collapse form of the girders is the same as that of those subjected to the centric loading. Web thickness proved to have considerable influence over the collapse form of the eccentrically loaded girders.

Deformation characteristics of aluminium alloys

The utilisation of aluminium alloys in structural applications requires knowledge of their characteristics in the elastoplastic area. The deformation of alloys in this area can be described by the Ramberg-Osgoods equation. Tensile test results for AW5083 and AW-2024 alloys are presented, and it is confirmed that strain hardening can reliably be described with Hollomon equation. Ramberg-Osgood equations are derived for these two alloys based on strain hardening indicators.

Ultimate Load Bearing Capacity of Web Members of Lattice Aluminium Structures Made of CHS Profiles

A joint of lattice aluminium welded structure made of circular hollow sections (CHS) has been analysed. Aluminium alloy EN AW 6082-T6 was used. Calculation of ultimate load bearing capacity of lattice structure web member assumes check of element load bearing capacity for the following calculation situations:- calculation of ultimate load bearing capacity of compressed elements with the influence of buckling,- calculation of ultimate load bearing capacity of compressed elements with the influence of HAZ,- calculation of ultimate load bearing capacity of tensioned elements with the influence of HAZ,- calculation of ultimate element force in truss joint, depending on joint construction.The first three checks are independent of type and characteristics of truss chords. They depend only on elements connection manner and geometrical characteristics of web members. The fourth condition directly depends on relation of chord and web member characteristics, i.e. ratio of their diameters and tube wall thicknesses. The choice of joint geometry, gap between elements in joint as well as joint eccentricity are also important for ultimate force in web member. Check of K-joint ultimate bearing capacity is particularly needed for welded joints due to aluminium strength decrease caused by HAZ (Heat Affected Zone) effect.European standard EN 1999 for aluminium structures design has not defined ultimate load of web members regarding type and characteristics of joint connection.Value of ultimate force in web member of K-joint, depending on connection type, by means of expressions defined in EN 1993-1-8 (Design of steel structures - Part 1-8: Design of joints), has been analysed. Comparative analysis has been done by means of ANSYS modelling, taking into consideration real characteristics of aluminium alloy and ultimate load bearing capacity reduction in the vicinity of weld due to HAZ effect. The main goal of the paper is to analyse capability of expressions from EN 1993-1-8 for steel structures to be used in aluminium structures, having in mind quoted limitations.

Deformacijske karakteristike aluminijskih legura

The utilisation of aluminium alloys in structural applications requires knowledge of their characteristics in the elastoplastic area. The deformation of alloys in this area can be described by the Ramberg-Osgoods equation. Tensile test results for AW5083 and AW-2024 alloys are presented, and it is confirmed that strain hardening can reliably be described with Hollomon equation. Ramberg-Osgood equations are derived for these two alloys based on strain hardening indicators.