Three full-scale experimental tests were conducted to investigate the strength and stiffness of weak-axis moment end-plate connections. Each test consisted of two girders connected to a column web with four-bolt extended moment end-plates. Two tests were conducted with bare steel. One test included a composite concrete slab that confined the top extension of the end-plate.

Finite element models of the tests were created with the commercial software SAP2000. A simplified modeling procedure was developed to overcome the contact problems between the end-plates and column web, and between the bolts and holes in the end-plates and web. The simplified modeling procedure accurately predicted the experimental elastic stiffness, in the form of column web rotations, of the connections.

Yield line theory was used to investigate the plastic strength of the column web. Several yield line patterns were examined. Analytical plastic moment strengths were very conservative when compared to the observed behavior of the column web.

The experimental stiffness of the test with the concrete slab confining the top extension of the end-plate was compared to the stiffness of a similar test without a slab. The slab increased the elastic stiffness of the connection; however, after the concrete began cracking and crushing around the connection, the stiffness was greatly decreased.