01.17: Photogrammetric analysis of thin end‐plate deformations in steel and composite joints

Abstract

ABSTRACTThe subject of the paper concerns the issues related to the deformability of the semi‐rigid beam‐to‐column joints with bolted end‐plate connections. Deformations of the relatively thin end‐plates of different thickness (ranging from 40 to 60% of the bolt diameter) and height (flush and extended) are analysed in steel and composite steel‐concrete joints with varying reinforcement ratio of the composite slab. The joints were originally subjected to hogging bending in the destructive experimental tests, carried out at the Warsaw University of Technology a few years ago. The obtained results, based on the moment‐rotation relationships, were investigated and reported elsewhere.The aim of the research presented here is a determination of the distribution and the values of the maximum plastic curvatures of the deformed end‐plates by means of the photogrammetric analysis. Application of the digital photogrammetry, called stereophotogrammetry, enabled reconstruction and 3D‐modelling of deformed plate surfaces as well as a presentation of the results in graphic and numerical formats. The results of the photogrammetric analysis allow for determining the yield line patterns, which are the basis for defining the effective lengths of particular end‐plate parts, modelled as equivalent T‐stubs. Such models are used for identification of failure modes as well as a calculation of the basic joint properties by means of the component method, adopted in EN 1993‐1‐8. The examined semi‐rigid joints with the end‐plates of the thickness approximately twice smaller than the bolt diameter, demonstrated the mechanism of complete yielding of the T‐stub flange, representing the end‐plate (related to Mode 1 according to EN 1993‐1‐8). However, the intensiveness of the yield line patterns differs visibly when the same types of end‐plates were used in case of steel and composite joints. The influence of the end‐plate deformations was smaller in the composite ones and decreased with increasing reinforcement ratio.Comparison of results based on the approach used in Eurocodes and those reported on the basis of photogrammetric analysis is presented.