Surprisingly positive results from the first of four large-scale tests of reinforced-concrete link beams with embedded structural steel sections have further opened the door to more-constructible concrete towers in highly seismic zones. Link beams over openings in concrete shear-wall cores have long been the bane of builders because of intense reinforcing-steel congestion, which slows construction.
During the first-ever large-scale test, the beam performed much better than anticipated. Given the importance of link beams in core-wall buildings, understanding performance at a meaningful scale is of "critical importance," says Ron Klemencic, president of structural engineer Magnusson Klemencic Associates (MKA), Seattle.