Marc L. Levitan recalls being at first enthralled by the sound and light show of the thunderstorms and then traumatized by the flooding in his neighborhood in Bucks County, Pa., during 1972’s Hurricane Agnes. He was 10.
“All my toys were floating around in the basement,” says Levitan, who remembers his father rescuing a neighbor’s dog and his mother’s fear. “It was surreal,” he says.
In Levitan’s mind, there is a link between that formative experience and his life’s work: taming the destructive power of storms. His greatest achievement to date is the historic premiere of provisions on tornado-resistant design in the structural engineers’ bible on loads.
“This is all brand new, even within the technical community,” says Levitan, lead research engineer in the National Windstorm Impact Reduction Program of the National Institute of Standards & Technology (NIST) and chair of the ASCE/SEI 7-22 task committee on tornado loads, which developed Chapter 32 of ASCE/SEI 7-22: Minimum Design Loads & Associated Criteria for Buildings & Other Structures.
“Marc’s dedication has been outstanding and single-focused,” says Donald Scott, a senior principal with PCS Structural Solutions and chair of the wind load subcommittee for ASCE 7-22. “The code will save lives as we implement it,” he adds.
调用标准”意义重大,”斯科特也credits Levitan’s tornado research at NIST for the profession’s first understanding of the structure of the wind and how to design for pressure loadings on buildings.
“I like to see research benefit society,” says Levitan.
Levitan and his NIST team started working toward the goal of a national standard for tornado-resistant design soon after a twister devastated Joplin, Mo., on May 22, 2011. In 2014, NIST published a report of its investigation of the storm, led by Levitan. In it, NIST called for improved measurement and characterization of tornado hazards and new methods for tornado-resistant design of buildings.
NIST在2018年的ASCE 7-22风载小组委员会的第一次会议上提出了龙卷风分会的想法。随后进行了讨论，主要是关于该方法的最佳位置。稻草民意调查确定它应该是标准本身的一部分，而不是附录或评论。
龙卷风较弱
这些规定仅适用于较弱的龙卷风。列维坦说，有一个误解，认为有必要为最糟糕的龙卷风设计或什么都不做。他说，飓风或地震并非如此。他补充说：“每年的损害中的大部分损害都是由较弱的龙卷风造成的，”因为还有更多的损害。
该标准还仅适用于被归类为基本设施的龙卷风易发区的建筑物，例如医院和公共集会场所。
目前，Levitan正在研究龙卷风设计的结构性成本溢价，并在强风暴中进新利18备用行了风速估算的单独标准。他说，这项工作“仅处于起步阶段”。
