Initial stiffness of bolted joints used in steel thin walled structures

Bolted lap joints are often used in steel thin walled structures. In the global analysis, this kind of joints is conventionally considered as a hinge. Such simplification has an influence on increasing the value of bending moment in a beam, and the size of its cross section. In fact, such connections are semi-rigid. Their moment-rotation (M-Fi) characteristic can be effectively predicted by experimental testing, but such tests in a majority of cases are costly and labour-absorbing. The numerical simulations are alternative method to obtain the flexibility parameters of such joints. This simulations can be carried out using the computer software based on FEM, ie. ADINA software. A next possibility to obtain joint flexibility characteristics is mechanical modeling of the joint. This paper presents the mechanical model of bolted lap joint permitting to calculate the initial stiffness of connection. To create this model a component method was used.