9416457 Popov A coordinated research effort on steel beam-to-column joints is conducted in this project. The study will concentrate on the fundamental problems of welding and connections. Some subassemblages will be tested to study: 1. The effect of backing bars. By experiments with backing bars and with such bars removed and weld roots cleaned and rewelded, the extent of improvement in behavior would be documented. 2. The effect of dams and run-off tabs at the ends of full- penetration groove welds. A few experiments illustrating the influence of such dams versus run-off tabs would be valuable. 3. The general use of FCAW high deposition electrodes. Although the FCAW high deposition electrodes are almost universally used, laboratory experience using GMAW (stick) often shows better results. 4. The contribution of preheat and controlled cooling to the integrity of joints. Cases where AWS guidelines are exceeded or violated would indicate sensitivity to this parameter. 5. The effect of size on joint integrity. In many of the failed joints during the Northridge Earthquake, steel member sizes, driven by desire for long clear spans, were very large. 6. Improved details for large-size connections. Some possible details will be studied for enhancing such joints by forcing the critical plastic hinge away from the face of the column. Testing of several specimens of different size is contemplated. This may include specimens with concrete slabs. Capacity analyses will be used in establishing member sizes, as well as in developing design requirements. 7. Residual Stress Distribution. The residual stresses together with those imposed by dead and live (earthquake) loads that can cause failures of the type repeatedly observed in steel building joints in the damaged area. 8. Cantilever Beam-Column Subassemblages. It is planned to fabricate and test two conventional beam-column subassemblages. 9. Cantilevers on Both Sides of Col umn. Due to limitation of the funds, only a single specimen is contemplated. The main purpose of this test is to study the panel zone, as well as beam connections. This project is coordinated with companion projects at the University of California at San Diego and at the University of Texas at Austin. This is a Northridge Earthquake project. ***
