Motivated by concern about life safety, inconsistent or nonexistent building code enforcement and a lack of appropriate design guidance, a group of structural engineers has crafted the first-ever environmental hazard load-resistance requirements tailored specifically to public-occupancy temporary structures, such as outdoor stages and tents. The provisions, proposed for the 2024 edition of the model building code, are out for public comment until June 20.

娱乐产业special-event interests say the loading requirements, which are stricter than those currently used, would increase the cost of stages and place a serious economic burden on the outdoor-event business.

The need for improved and consistent structural regulation across the U.S. for environmental hazards such as wind, snow, floods and earthquakes became apparent to many building officials in 2011, when there were three temporary-structure failures, including that of a rock concert stage at the Indiana State Fairgrounds. That collapse killed seven people.

No Good Guidance

Magnusson Klemencic Associates地震工程总监，All-Od-Or-Od Hoc委员会成员John Hooper说，团体正在建立“这些临时结构”。International Code Councilthat submitted code-change proposal S116-22 for ICC's 2024 edition of the model International Building Code (IBC).

唐纳德·斯科特（Donald Scott）是PCS结构解决方案的高级负责人，委员会的负责人，称S116-22“非常重要”，尤其是对于在美国建筑官员之间具有管辖权的当局“没有统一或一致的方法来允许临时结构，”他说，通常属于消防元帅和消防法规的权限，而不是建筑物部。

The proposal would drastically modify IBC chapters 31 and 16. The code currently calls for designing temporary structures to the same standard as permanent structures, which engineers say is overkill. And few if any building officials even enforce the section on public-occupancy temporary structures, according to Ali Fattah, assistant deputy director in the city of San Diego's Development Services Dept., Division of Building Construction and Safety.

The proposal defines public-occupancy temporary structures as new buildings or structures that are used by the general public, or that support public events, where the public expects similar levels of reliability and safety offered by permanent construction. Public-occupancy temporary structures are often assembled with reuseable components that are disassembled and shipped to another event for reassembly. They are designed for a particular purpose and a specific period of time, which the proposal defines as less than one year.

“We are creating a set of provisions that the jurisdiction can use to regulate temporary structures that are accessed by the public,” says Jennifer Goupil, director of codes, standards and technical initiatives at the Structural Engineering Institute of the American Society of Civil Engineers, which develops the bible on design loads, known as ASCE 7.

Lower Design Loads

The goal is to provide lower design loads—compared to permanent structures—for the temporary-structure designers, while maintaining the same level of reliability and risk to the public, adds Goupil, also a member of the ICC ad hoc committee.

“Temporary structures should not pose more risk to occupants than permanent structures, but because the code’s design-level environmental loads are far less likely during a temporary event, this proposal makes adjustments to reduce the requirements for a consistent level of risk,” says the proposal.

Gary Storm, the senior principal with Thornton Tomasetti who investigated the Aug. 13, 2011, fatal collapse of the stage at the Indiana State Fairgrounds, supports the code change proposal. “I think this is a terrific document,” he says.

The components of the stage structure at the fairgrounds were only designed for hanging loads, such as lighting equipment, adds Storm. “This structure had zero capacity for lateral loads,” he says.

2011年三场失败

Storm补充说，2011年暂时的公共占用结构发生了三个失败。每个事件的情况不同，但“一个共同的分母是缺乏[总系统]工程学”。

娱乐服务与技术协会（ESTA）的助理技术标准经理理查德·尼克斯（Richard Nix）表示，由于要求“设计风速压力增加15.6％”，这将增加阶段的成本基于正在建设中的不完整结构的标准，称为ASCE 37。

“We think it is okay to use ASCE 37 and have been since 2006,” says Nix.

ASCE 37 allows a 60% design load reduction over permanent structure load requirements and S116-22 allows only a 25% reduction, says Fattah, also an S116-22 committee member.

ASCE 37不合适

The committee maintains that ASCE 37 is not an appropriate standard to use because construction sites are not occupied by the public. “We oppose the use of ASCE 37” because, unlike the general public, construction workers are trained in safety procedures and understand the implied risk of an incomplete building, says Scott.

“The special event industry was never really entitled” to use ASCE 37 in the first place, for it does not take into account public safety, adds Fattah.

该提案介绍了受控占用的概念，以解决无法合理缓解环境负荷危害的情况，并允许基于预先批准的动作计划采取行动，建筑物官员可以使用该计划来允许安装无法抗拒代码规定的负载。

For example, flood hazard areas and tsunami inundation zones are clearly mapped, and evacuation plans are adopted and include tsunami-alert warning systems. Temporary structures subject to high wind loads may be evacuated and have sections removed to reduce the wind load, says the proposal.

Nix希望对当前的修改proposal that would give groups graduated and greater discounts, in terms of load-resistance requirements, based on the life span of the temporary structure and the development of an emergency action plan, such as evacuating the public or taking components down to reduce the hazard.

“We want a higher discount for administrative controls" than is currently proposed, Nix says, adding that he is hopeful a consensus can be reached.

Direct Modification of the Code

It is unusual for structural engineers to propose direct modifications to the IBC, rather than first developing an ASCE standard that is then referenced in the IBC.

“我们决定直接修改IBC因为我们could do it faster than waiting for the next edition of ASCE 7,” in 2028, says Hooper. That would be time for inclusion in the 2030 edition of the IBC, he says, adding that the current strategy, if successful, will include provisions in the model code six years sooner.

ICC公开评论听证会定于9月14日至21日在肯塔基州路易斯维尔举行，将考虑在公众意见期内收到的拟议修改，并为符合条件投票之前的代码更改提案提供时间和反对代码变更建议的时间。成员。在线政府共识投票之后。该提案的命运应在年底之前封印。

The ICC ad hoc committee, which includes members of the main committee of ASCE 7, is gearing up to turn the provisions into ASCE's first-ever consensus standard for public-occupancy temporary structures. “The provisions are 70% to 80% ready for ASCE," says Scott.