Biljana Šćepanović

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.

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.