Starting in mid-2020, following the outcome from the 2019 International Code Council’s (ICC) Group B Hearings, an ad hoc committee of dedicated experts from the ASCE/SEI 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures committee began a two-year process to develop a code change proposal for the next cycle of the ICC Hearings in 2022. This happens all of the time, but this effort was the epitome of collaboration.
The catalyst for this dedicated committee effort was to deliver on a promise made on the floor of the hearings: to work together to find an appropriate solution for needed code provisions for minimum structural loads for temporary structures. Unfortunately, in past code cycles, inappropriate references were attempted to be introduced to the International Building Code (IBC) as a design basis and requirement for temporary structures but failed due to lack of consensus within the industry and direct objection from ASCE/SEI 7 committee leadership. Following the failed attempt in 2019, and the fact that ASCE led the objection, ASCE/SEI 7-22 wind loads subcommittee chair Don Scott led the efforts of a diverse group of experts from the committee, building officials from many jurisdictions from across the country that have experience with large events and temporary structures, and industry representatives from the U.S. entertainment industry. The group developed provisions that align with the design basis for IBC Chapter 16 and ASCE/SEI 7, as well as provide the appropriate level of risk and structural reliability to the public. As a result of this collaboration, a new section 3103 Temporary Structures has been approved for adoption into the 2024 IBC, which addresses wind, seismic, snow, flood, and ice loads with direct pointers from those sections of IBC Chapter 16.
NEW SECTION 3103 TEMPORARY STRUCTURES
The ICC’s I-Codes regulate the construction of new buildings and temporary structures through IBC Chapter 31. Since Temporary Special Event Structures are regulated by the International Fire Code, but also are a type of temporary structure, those structures also need to meet the requirements of this new section.
In addition to the new Section 3103, four new definitions are added to Section 202 Definitions for public-occupancy temporary structures, service life, temporary event, and temporary structure. Public-occupancy temporary structures are 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 as offered by permanent construction. Public-occupancy temporary structures are often assembled with re-useable components and designed for a particular purpose and defined period of time, which is defined as a temporary event when the period of time is less than one year. Public-occupancy temporary structures in service for a period that exceeds 1-year are required to comply with the IBC for new buildings. 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. The code change addresses the hazards in the built environment in IBC Chapter 16 for public-occupancy temporary structures. The code change includes the ability to mitigate some hazards through Emergency Action Plans and controlled occupancy to address cases where an environmental loading hazard cannot be reasonably mitigated. This allows a Building Official to use a preapproved action plan to permit installations that cannot resist code prescribed loads. For example, in mapped areas such as flood hazard areas and tsunami inundation zones evacuation plans can be adopted and temporary structures subject to high wind loads may be evacuated and have sections removed to reduce the wind load. The code change proposal recognizes that it may be desirable for a temporary structure to remain in service for more than 180 days, whether continuously occupied or not, and provides a process that the Building Official can follow to facilitate such an extended service period. However, after 1-year has passed, the structure is required to comply with requirements for new buildings or is removed from service by being disassembled.
NEXT STEPS
Due to the staggered nature of the ICC and ASCE 7 Standard code development processes, this IBC proposal is the first of two efforts to address the need for provisions for loads on temporary structures. The second effort includes development of a new chapter to ASCE/SEI 7 to address temporary structures. Additionally, the Fire Code will be updated to reflect the new IBC definitions and section in Chapter 31. As the work continues in the 2028 cycle of ASCE/SEI 7, the goal is to bring the design requirements into the standard, remove them from the code, and then update the code to point back to ASCE/SEI 7.
In summary, this is an amazing example of how the leadership of members of the ASCE/SEI 7 ad hoc committee worked across the industry to fill a gap in the code and fulfil its promise to the industry. Two years later, in partnership with industry and many key stakeholders, new provisions have been developed that will lead to safer more reliable temporary structures.
The ad hoc committee included the following members: Chair Don Scott; Jennifer Goupil; Therese McAllister, Ph.D.; John Hooper; John Duntemann; Andrew Stam; Bryan Lanier; Chris Cerino; James (Greg) Soules, Ph.D.; Ali Fattah; and Constadino (Gus) Sirakis.