STEEL FIBROUS, DUCTILE CONCRETE JOINT FOR SEISMIC-RESISTANT STRUCTURES

Tests were made of a ductile concrete joint designed to minimize steel congestion common to seismic-resistant building joints. An experimental comparison was conducted on two full-sized, beam-column joints. One was a conventional joint using hoops in accordance with the seismic-resistant design specifications of ACI 318-71; the other was a modified joint using steel fibrous concrete in the joint region in lieu of the hoops. The joints were subjected to loading representing the effect of two major earthquakes. The modified steel fibrous concrete joint developed a higher ultimate moment capacity and was somewhat stiffer than the conventional joint. The modified joint appeared to be more damage tolerant and resisted cracking better than the conventional joint. Fabrication of the modified joint was simpler and concrete placement was made easier because of reduction of steel congestion. It is estimated that use of the modified joint in building construction would result in savings of about $100 per joint.