ABSTRACT
The beginning of steel-tiered construction for multistory buildings can be traced to the construction in 1884 of the 20-story Home Insurance Building, Chicago, which incorporated a steel frame which was heavily encased in masonry.l
The masonry enclosures in these initial applications provided the necessary stiffening for wind forces. As the masonry enclosures were made less massive to take advantage of the load carrying capacity of the steel skeleton, the burden of wind stiffening was transferred to the steel frame. The progressive evolution of moment connections at beam-column joints from semi-rigid to rigid was instrumental in making the steel skeletal frame an effective lateral load resisting system. Initially, brackets were provided on the cast iron column which supported the beam element with a horizontal tie at the top of the beam to develop some continuity. Fully rigid moment connections started to evolve with the use of profiled shapes. Angle or T-shapes were used to connect beam and column flanges by riveting to develop continuity.
