Trailblazers seeking a faster, safer and less costly way to build concrete shear walls in seismic-zone high-rises have pioneered the use of steel fibers as link-beam reinforcing-steel "decongestants." Having smoothed the path and proven the concept on a limited basis in a 24-story tower in Seattle, the builders of The Martin Apartments say they are eager to use the approach on a broader scale.
"This unties the Gordian knot in seismic link beams, which have [bedeviled] contractors for years," says Cary Kopczynski, the force behind the rebar decongestants and president of the Bellevue, Wash.-based structural engineer that bears his name.
“我绝对会再次签约，”马丁在埃克萨尔太平洋总承包商西雅图办事处的马丁项目负责人布莱恩·福斯特（Brian Foster）说。他说，如果从工作开始就使用了“这是一种劳动和节省时间”。
跨越剪切壁开口的地震连接梁特别具有挑战性。除了带有领带和马rup的水平钢筋外，规范性的地震代码还需要厚实的X形条（Gordian结）很难插入，因为它们经常与水平杆相撞。
Batch-plant-mixed steel-fiber-reinforced concrete (SFRC), which is ductile and strong, cuts link-beam rebar by about 40%. The approach eliminates diagonal bars and reduces the size of the flexural and shear bars that remain, says Kopczynski, who has been trying to use SFRC beams for a decade.
The Martin, topped out in December, has five link beams per level. For the first installation, Kopczynski chose fibrous concrete for the two most challenging beams—those near the core's corners—which have the heaviest diagonals and are the toughest to install. "We wanted to walk before we ran," he says.
In the future, Kopczynski envisions SFRC applications beyond seismic link beams, including ductile moment-resisting frames with highly reinforced beams and columns. Soon, concrete with fiber, like adobe with straw, will be a homogenous material, he says.
马丁的SFRC每立方码的价格约为800美元，是传统混凝土的10倍。Kopczynski说：“所有利益相关者都谨慎地进入了该项目，并定价反映了这一点。”
福斯特同意，称SFRC的真实成本约为每立方公C $ 350。
如果新颖的SFRC系统没有获得城市的认可，则本地开发商的整个建筑物常规允许。Vulcan Inc.设计和建设高级总监Andrew Clapham说：“这是作为变更订单做到的。
为了降低成本并减轻流新利18备用官网登录程，Kopczynski计划使用许多供应商的纤维率领额外的性能测试。工程师预测：“市场竞争结合纤维剂量的减少将使未来的项目能够实现大量成本并计划节省。”新利18备用网址
