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.MKA is one of
The market is generally healthy and steadily growing, and margins are up for large specialty contractors. Further, advances in design tools and owner demand for collaboration are giving subcontractors a seat at the table early on in projects.