Effects of transient creep strain on post-tensioned concrete slabs in fire

Wei, Ya; Au, Ftk; Li, Jingyuan; Tsang, Neil C. M.

doi:10.1680/jmacr.15.00266

Cited by 7 publications

(3 citation statements)

References 31 publications

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“…Stress–strain relations of concrete and prestressing strands, plotted as function of fire exposure time, are shown in Figure 5. The high-temperature creep effects in steel and concrete are implicitly accounted in stress-strain relations (Kodur and Dwaikat, 2010; Wei et al, 2017).…”

Section: Numerical Analysis Methodsmentioning

confidence: 99%

Performance of prestressed concrete box bridge girders under hydrocarbon fire exposure

Song

Zhang

Hou

et al. 2020

Advances in Structural Engineering

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This article presents an approach for investigating performance of prestressed concrete box bridge girders under hydrocarbon fire exposure. A three-dimensional nonlinear finite element model, developed in computer program ANSYS, is utilized to analyze the response of prestressed concrete box bridge girders under combined effects of fire exposure duration and simultaneous structural loading. The model validation is performed using a scaled prestressed concrete box girder exposed to ISO834 fire in furnace. Subsequently, the validated model is used to investigate fire performance of prestressed concrete box bridge girders through taking into consideration some variables, namely concrete cover thickness to prestressing strands, prestress degree, load level, fire exposure length, and position. Through a case study, results from numerical analysis show that concrete cover thickness to prestressing strands and load level has significant effect on fire resistance of prestressed concrete box bridge girders. Increasing prestress degree in prestressing strands can speed up the progression of deflection (sudden collapse) in prestressed concrete box bridge girder toward the final fire exposure stage. Reducing fire exposure length or preventing fire exposure on mid-span zone can highly enhance the fire resistance of simply supported prestressed concrete box bridge girders. Failure of prestressed concrete box bridge girder, under hydrocarbon fire exposure conditions, is governed by rate of deflection failure criterion in particular cases.

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Section: Numerical Analysis Methodsmentioning

confidence: 99%

Performance of prestressed concrete box bridge girders under hydrocarbon fire exposure

Song

Zhang

Hou

et al. 2020

Advances in Structural Engineering

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“…The importance of understanding the behaviour of concrete materials in fire is very certain. This special themed issue of Magazine of Concrete Research contributes to our understanding of what has been achieved and what remains to be done in order to provide the fire safety engineering design and improved fire performance of concrete structures.This themed issue contains seven papers and presents results from both experimental and numerical studies on the fire behaviour of various concrete structures, ranging from the mechanical properties of concrete and steel reinforcement at elevated temperatures to the overall performance of concrete structures in fire.In the paper presented by Wei et al (2017) the authors investigated the effects of transient creep strain of concrete on post-tensioned concrete slabs with unbonded tendons by using three-dimensional nonlinear finite-element analysis models. In their study, three concrete constitutive models were employed, one without transient creep strain and the other two with either explicit or implicit consideration of transient creep strain.…”

mentioning

confidence: 99%

“…In the paper presented by Wei et al (2017) the authors investigated the effects of transient creep strain of concrete on post-tensioned concrete slabs with unbonded tendons by using three-dimensional nonlinear finite-element analysis models. In their study, three concrete constitutive models were employed, one without transient creep strain and the other two with either explicit or implicit consideration of transient creep strain.…”

mentioning

confidence: 99%

Editorial: Fire safety engineering design of concrete structures

2017

Magazine of Concrete Research

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Reducing deaths in fires and the impact of fire damage on buildings requires a comprehensive approach to fire safety. The structural fire safety capacity of concrete is very complicated because concrete is a heterogeneous material with considerable variations. When concrete is subject to sufficient heat such as from a fire the free water that fills the concrete pores and water chemically bound to the cement will evaporate. If the evaporation rate is greater than the vapour migration rate, pore pressure will build up. This built-up pore pressure, combined with the reduction in strength caused by elevated temperatures and the increase in stresses due to thermal effect, can cause concrete spalling and damage to structures. In addition, developments in concrete mix design have led to new types of concrete -including high-strength, ultra-high-strength and self-compacting concrete -which, besides having an increased structural performance at ambient temperature, have also shown a different performance when exposed to fire. The importance of understanding the behaviour of concrete materials in fire is very certain. This special themed issue of Magazine of Concrete Research contributes to our understanding of what has been achieved and what remains to be done in order to provide the fire safety engineering design and improved fire performance of concrete structures.This themed issue contains seven papers and presents results from both experimental and numerical studies on the fire behaviour of various concrete structures, ranging from the mechanical properties of concrete and steel reinforcement at elevated temperatures to the overall performance of concrete structures in fire.In the paper presented by Wei et al. (2017) the authors investigated the effects of transient creep strain of concrete on post-tensioned concrete slabs with unbonded tendons by using three-dimensional nonlinear finite-element analysis models. In their study, three concrete constitutive models were employed, one without transient creep strain and the other two with either explicit or implicit consideration of transient creep strain. The results showed that, the model without transient creep strain is too conservative in fire scenarios by giving much larger deflection and higher tendon stress although the model is sufficiently accurate at ambient temperature. In contrast, the models with transient creep strain were found accurate in fire scenarios. However, if the transient creep strain was overestimated, the slab deflection and tendon stress would be reduced, indicating that the transient creep strain has a positive effect on structural fire resistance. Thus it was concluded that the transient creep strain should be considered in the analysis by either an implicit or an explicit approach for its positive contribution to the fire resistance of post-tensioned concrete slabs.The paper contributed by Zhang et al. (2017) was on the mechanical properties of pre-stressing steel both in and after the fire. Empirical formulae were proposed based on experime...

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