Robert J. Dexter, Principal Investigator

Finite-Element Modeling of Steel Structures

During the 1994 Northridge earthquake in California, the connections of steel girders to columns in steel frame buildings fractured unexpectedly. These catastrophic fractures created a strong need to study the details and design provisions of these connections further.

This group’s research project focused on understanding the behavior of the stiffeners in the connections, including the behavior of the column continuity plates and the web doubler plates. Analysis was conducted using ABAQUS. These parametric studies were used to compare the experimental results and to aid in providing guidelines for new design recommendations of these steel connections.

Finite element models were created for all test specimens. The results of these analyses and an examination of the design provisions for local web yielding and local flange bending were the basis of the experimental specimen selection.

The principal results clarified the need for and design of transverse stiffeners and doubler plates and to gain additional knowledge to create lower-cost, easier-to-fabricate steel structures.

New research begun by this group is intended to develop guidelines for weld repairs on ships. Fatigue cracks are not unusual in commercial ships such as tankers and bulk-carriers. These fatigue cracks are primarily an expensive nuisance, requiring weld repairs that often crack again within a short period of time. A reliable method to estimate the residual fatigue life of typical weld repairs would facilitate rational and efficient design of more reliable weld repairs as well as scheduling for critical inspections. This research project is intended to develop guidelines for specific repairs and to determine the restored life as a result of these repairs. The proposed research will include both experimental work as well as a parametric study using finite element analysis. The analysis will be conducted using ABAQUS. These parametric studies will be used to compare with the experimental results and to aid in providing guidelines for optimal repair recommendations.

Research Group and Collaborator

Jerome F. Hajjar, Faculty Collaborator
David St-Peter, Graduate Student Researcher
Clifford Youngberg, Graduate Student Researcher