09.10: Shear damage evaluation of bolted steel joints

Abstract

ABSTRACTThe purpose of this study is to address a way of predicting the ductility capacity of steel joints. Recent research studies show that a joints’ ability to perform under elevated deformations, without fracturing, is a key factor in enabling mechanisms preventing collapse to be developed, and thus, improve the overall robustness of steel framed structures. This theme is becoming rather timely as building owners and insurers try to assess the collapse risk of their buildings, and the probability of a wide spread collapse if subjected to extreme events, either due to natural or terrorist causes. However, regarding this matter, current design code guidelines are limited to a prescriptive approach, by recommending a nominal tying force to be met, or quantifying a force that reproduces accidental scenarios, such as an impact of a vehicle, ships or helicopters, which do not address the overall behavior and performance of the structure.This paper presents an evaluation of the shear damage state of a bolted steel joint. For that, it is necessary to establish the shear damage parameters that are required to numerically obtain the rupture of steel elements, allowing the prediction of the ductility of steel joints. Previous authors’ research has showed that a ductile damage model may be insufficient to capture its end‐plate fracture and to establish a joints’ rupture. Hence, this study looks forward to improve the damage threshold for smaller triaxial stress states, within the shear and compression zones.In order to achieve this objective, a finite element model is developed and compared with real scale test results of a bolted steel joint under bending. The numerical model takes into account the strain softening of the material by means of a continuum damage mechanics approach and making use of the “element deletion” technique to approximate the fracture pattern of the studied joint. The analyses are carried out using the finite element software ABAQUS.