Predicting residual deformations in a reinforced concrete building structure after a fire event

Ni, Shuna; Gernay, Thomas

doi:10.1016/j.engstruct.2019.109853

Cited by 40 publications

(11 citation statements)

References 27 publications

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“…Although a fire can result in deteriorations of the mechanical property of HSC, causing the decrease of the bearing capacity of a component, the structure rarely collapses during a fire 23,24 . Consequently, HSC element and structure continue to be in service after the post‐fire safety assessment and/or repair.…”

Section: Research Significancementioning

confidence: 99%

Reliability analysis of the residual moment capacity of high‐strength concrete beams after elevated temperatures

Xie

2020

Structural Concrete

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A series of tests were conducted to study the variability of the residual compressive strength for high‐strength concrete (HSC) after elevated temperatures, and then a calculation process was developed to study the reliability of the residual moment capacity of HSC beams after a fire. The experimental results indicated that the mean values and the characteristic values of the residual compressive strength of HSC were reduced with the increasing elevated temperatures. The standard deviation of the residual compressive strength of HSC was increased when the temperature ranged from 20 to 400°C and decreased from 400 to 800°C. Regardless of the elevated temperatures, the residual compressive strength of HSC followed the normal distribution. The reliability index of the residual moment capacity of HSC beam was decreased with the increasing fire duration. The decrease rate of the reliability index became lower and kept constant when the section height–width ratio was beyond 2.75 and the longitudinal reinforcement ratio was higher than 1.43%. As the load effect ratio was increased, the decrease rate of the reliability index was reduced regardless of the section size, the height–width ratio, and the reinforcement ratio.

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Section: Research Significancementioning

confidence: 99%

Reliability analysis of the residual moment capacity of high‐strength concrete beams after elevated temperatures

Xie

2020

Structural Concrete

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“…Future works will seek to include more damage characteristics, e.g., residual axial deformation will be incorporated into the fire loss estimation of a column; more cost components in Eq. (1); and to conduct the optimization of design parameters at the scale of a whole building, the importance of which has been emphasized in [24].…”

Section: Discussionmentioning

confidence: 99%

Lifetime economically optimum position of steel reinforcement in a concrete column exposed to natural fire

Ni¹,

Coile²,

Khorasani³

et al. 2020

Proceedings of the 11th International Conference on Structures in Fire (SiF2020)

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This paper incorporates a probabilistic fire loss assessment method for reinforced concrete structures into a cost-benefit analysis to optimize a structural fire design. Economic losses in case of failure and survival of the structure are both quantified with, in the latter case, an estimate of the damage and repairs costs. As a case study, a cost-benefit optimization of the position of rebars in a concrete column is investigated. The column response in fire is evaluated using finite element simulations in SAFIR. Variations in cover thickness result in variations in failure probabilities and, for cases where no failure occurs, variations in repair costs due to heat penetration and residual out-of-plane deformation of the column. The optimum cover thickness is the one that offers the best trade-off between the various repair costs across the range of likely fire intensity levels. This optimum is sensitive to repair decisions such as the tolerance on the acceptable residual out-of-plane deformation after a fire. For the studied cases, the optimum cover thickness is smaller in slender columns than in stocky columns due to greater out-of-plane deformations in the former.

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“…The compressive strength of the concrete is conservatively estimated to be 20.7 MPa (3000 psi) with tensile strength equal to 13.7% of compressive strength (2.8 MPa). The stress-strain model for calcareous concrete includes explicit transient creep (35), which promotes an increasingly accurate prediction of residual deflections in fire-exposed reinforced concrete elements as per recent research by SAFIR developers (36,37). Tensile cracking is modeled using a smeared crack model with a descending branch to zero stress.…”

Section: Thermo-mechanical Analysis Approachmentioning

confidence: 99%

Vulnerability of Drop Ceilings in Roadway Tunnels to Fire-Induced Damage

Ouyang

Guo

Quiel

et al. 2021

Transportation Research Record: Journal of the Transportation R

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Roadway tunnels often include a reinforced concrete drop ceiling that is hung from the liner to create a plenum that facilitates ventilation and houses utilities. Drop ceiling panels are lightweight compared with the much thicker tunnel liner and can experience significant damage from a fire on the roadway below. This paper examines the flexural response of drop ceiling panels in two representative tunnels to standard fire curves as well as several realistic fires due to vehicular accidents. Standard fire demands as per the Rijkswaterstaat and ASTM E1529 fire curves are uniformly applied to the ceiling panels, and heat exposure contours for typical vehicle fires with heat release rates of 30, 100, and 200 MW are generated from the software CFAST. The finite element analysis software SAFIR is used to evaluate the thermo-mechanical behavior of the ceiling panels when subjected to various thermal demands from the fire below. The analysis results indicate that drop ceiling panels are highly vulnerable to fire-induced damage and potential collapse both during a fire’s active heating phase (from simultaneous loss of capacity and restraint of thermal expansion) and during the subsequent cooling period (from tension that develops when the permanently deformed panel thermally retracts). The potential for fire-induced damage or collapse of the drop ceiling panels can be mitigated by reducing the fire hazard, removing the drop ceiling, or enhancing the fire resistance of the panels via the application of passive protection or structural hardening.

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Predicting residual deformations in a reinforced concrete building structure after a fire event

Cited by 40 publications

References 27 publications

Reliability analysis of the residual moment capacity of high‐strength concrete beams after elevated temperatures

Reliability analysis of the residual moment capacity of high‐strength concrete beams after elevated temperatures

Lifetime economically optimum position of steel reinforcement in a concrete column exposed to natural fire

Vulnerability of Drop Ceilings in Roadway Tunnels to Fire-Induced Damage

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