Development of A Cast Modular Connector for Seismic-Resistant Steel Moment Frames Part I: Prototype Development

A cast modular connector (MC) has been developed for use in seismic-resistant steel moment frames. The MC is a field bolted beam flange connection intended to serve as the frame's special energy-dissipating detail. The connector is specifically configured for optimal seismic performance through a casting process. The MC possesses inherent ductility through variable-section arms that minimize plastic strain demand and a reliable yet economical fastening method through a base end-region that virtually eliminates prying forces on bolts. This paper focuses on the development of a Beta prototype design for the MC. This development process focused on the isolated connector rather than full-connection behavior. The MC Beta prototype design was developed using a comprehensive analytical investigation of trial configurations and key parameters using nonlinear (material and geometry) finite element analysis. Lessons were learned from an Alpha prototype. Designs were alternately evaluated for structural performance and castability through the electronic exchange of solid model files with steel foundry industry partners. The analytical results indicate the potential for excellent ductility and energy dissipation characteristics in the MC Beta prototype. A subsequent companion paper will describe the creation of a physical prototype and the experimental program that provides verification of the analytical results presented here.