SENSITIVITY ANALYSIS RESULTS ON THE SEPARATION PROBLEM OF BOLTED STEEL COLUMN-TO-COLUMN CONNECTIONS

The present paper deals with the sensitivity analysis of bolted steel column-to-column connections, by taking into account the development o f separation phenomena on the joint endplates. A variational inequalit y and quadratic programming approach is first proposed to the investig ation of the separation problem on such bolted steel connections. Appl ying the classical unilateral contact law to describe in a quasi-stati c way the separation process along the surface between the splice plat es, the continuous problem can be formulated either as a variational i nequality or equivalently as a quadratic programming problem. Then, by means of an appropriate finite element discretization scheme, the dis crete problem is formulated as a quadratic optimization problem with i nequality constraints. In order to investigate the variation of the st ructural response of the connection under consideration due to the var iation of critical design parameters, the sensitivity analysis problem is formulated; the latter is a quadratic programming problem where de sign parameters appear only in the quadratic term. This problem can be effectively treated numerically by means of an appropriate quadratic optimization algorithm. The applicability and the effectiveness of the method are illustrated by means of two numerical applications.