Strategies for enhancing fire resistance of high-strength concrete structures

Figure: ACI

Fig. 1a+b: Variation in compressive strength as a function of temperature for normal-strength concrete (NSC/1a) and high-strength concrete (HSC/1b)

Figure: ACI

Fig. 2: Extent of spalling after fire tests in columns made from (a) NSC and (b) HSC

Figure: ACI

Fig. 3+4: Temperature distribution at various depths for NSC and HSC columns as a function of fire exposure time (3) and axial deformation for NSC and HSC columns as a function of fire exposure time (4)

Figure: ACI

Fig. 5: HSC columns with different fibers after fire resistance tests: (a) plain HSC; (b) HSC with polypropylene (PP) fibers; (c) HSC with steel (S) fibers; and (d) HSC with hybrid (PP and S) fibers

Figure: ACI

Fig. 6: Reinforcement in concrete columns: (a) NSC with ties with 90-degree hooks; and (b) HSC with ties with 135-degree hooks and closer tie spacing

Figure: ACI

Fig. 7: Spalling in HSC columns after fire resistance test: (a) ties bent at 90 degrees; and (b) closer spaced ties bent at 135 degrees

Figure: ACI

Venkatesh Kumar R. Kodur, FACI,
University Distinguished Professor and Director of SAFE-D Center in the Department of Civil and Environmental Engineering at Michigan State University, East Lansing, MI. His research interests include evaluation of fire resistance of structural systems through large-scale fire experiments and numerical modeling and characterization of materials under high temperature. He is a member of ACI Committees 440 and 544, Joint ACI-TMS Committee 216, Fire Resistance and Fire Protection of Structures, etc.

Courtesy of the American Concrete Institute, www.concrete.org, this paper focuses on strategies for enhancing fire resistance of high-strength concrete structures, written by Venkatesh Kumar R. Kodur, FACI, University Distinguished Professor and Director of Safe-D Center in the Department of Civil and Environmental Engineering at Michigan State University, East Lansing, MI.

Resiliency is a key parameter for critical infrastructure. Concrete structures exhibit a high level of resiliency in terms of safety, robustness, durability, and disaster resistance. However, while resilience is evaluated under extreme loading conditions like blast, earthquake, and impact, it is not specifically considered under fire hazards.

Fire can occur as a primary event due to natural origins (lightning or an accident) or as a secondary event (following an earthquake, blast, explosion, or impact). Worldwide, fires cause thousands of deaths and billions of dollars of damage yearly. In the...