pore pressure | An-Najah Staff

Effect of Fire Induced Spalling on the Response of Reinforced Concrete Beams

Sun, 2014-06-01 12:27 — Monther Dwaikat

Journal Title, Volume, Page:

International Journal of Concrete Structures and Materials, Vol. 2, No. 2, pp. 71-81

Year of Publication:

2008

Link:

http://www.ceric.net/wonmun2/kci/KCI_3_2008_2_2_71(C).pdf

Authors:

Dwaikat M.B.

CEE Dept., Michigan State University, MI 48824, USA

Current Affiliation:

Building Engineering Department, Faculty of Engineering and Information Technology, An-Najah National University, Nablus, Palestine

[email protected]

Kodur V.R.

CEE Dept., Michigan State University, MI 48824, USA

Preferred Abstract (Original):

A macroscopic finite element model is applied to investigate the effect of fire induced spalling on the response of reinforced concrete (RC) beams. Spalling is accounted for in the model through pore pressure calculations in concrete. The principles of mechanics and thermodynamics are applied to compute the temperature induced pore pressure in the concrete structures as a function of fire exposure time. The computed pore pressure is checked against the temperature dependent tensile strength of concrete to determine the extent of spalling. Using the model, case studies are conducted to investigate the influence of concrete permeability, fire scenario and axial restraint on the fire induced spalling and also on the response of RC beams. Results from the analysis indicate that the fire induced spalling, fire scenario, and axial restraint have significant influence on the fire response of RC beams. It is also shown that concrete permeability has substantial effect on the fire induced spalling and thus on the fire response of concrete beams. The fire resistance of high strength concrete beams can be lower that that of normal strength concrete beams due to fire induced spalling resulting from low permeability in high strength concrete.

Hydrothermal Model for Predicting Fire Induced Spalling in Concrete Structural Systems

Sun, 2014-06-01 08:45 — Monther Dwaikat

Journal Title, Volume, Page:

Fire Safety Journal Volume 44, Issue 3, Pages 425–434

Year of Publication:

2009

Link:

http://www.sciencedirect.com/science/article/pii/S0379711208001239

Authors:

M.B. Dwaikat

Department of Civil and Environmental Engineering, Michigan State University, 3580 Engineering Building, East Lansing, MI 48824-1226, USA

Current Affiliation:

Building Engineering Department, Faculty of Engineering and Information Technology, An-Najah National University, Nablus, Palestine

[email protected]

V.K.R. Kodur

Department of Civil and Environmental Engineering, Michigan State University, 3580 Engineering Building, East Lansing, MI 48824-1226, USA

Preferred Abstract (Original):

A one-dimensional numerical model to predict fire-induced spalling in concrete structures is presented. The model is based on pore pressure calculations in concrete, as a function of time. Principles of mechanics and thermodynamics are applied to predict pore pressure in concrete structures exposed to fire. An assessment of the possibility of tensile fracture is made by comparing the computed pore pressure with temperature-dependent tensile strength. The pore pressure calculations are coupled with heat transfer analysis to ensure that the loss of concrete section, resulting from spalling, is accounted for in subsequent heat transfer analysis. The validity of the numerical model is established by comparing temperature, pore pressure, and concrete spalling predictions with results from fire tests. The computer program is applied to conduct case studies to investigate the influence of concrete permeability, tensile strength of concrete, relative humidity in concrete, and heating rate on fire-induced spalling in concrete members. Through these case studies, it is shown that permeability, tensile strength of concrete, and heating rate have a significant influence on fire-induced spalling in concrete. It is also shown that relative humidity has a marginal influence on fire-induced spalling in concrete.

Fire Induced Spalling in High Strength Concrete Beams

Sun, 2014-06-01 08:44 — Monther Dwaikat

Journal Title, Volume, Page:

Fire Technology, Volume 46, Issue 1, pp 251-274

Year of Publication:

2010

Link:

http://link.springer.com/article/10.1007%2Fs10694-009-0088-6

Authors:

M. B. Dwaikat

Department of CEE, Michigan State University, East Lansing, MI, USA

Current Affiliation:

Building Engineering Department, Faculty of Engineering and Information Technology, An-Najah National University, Nablus, Palestine

[email protected]

V. K. R. Kodur

Department of CEE, Michigan State University, East Lansing, MI, USA

Preferred Abstract (Original):

A macroscopic finite element model is extended to account for fire induced spalling in high strength concrete (HSC) beams. The model is based on the principles of mechanics and thermodynamics and utilizes pore pressure calculations to predict fire induced spalling in concrete. For validating the model, spalling measurements were made by conducting fire resistance experiments on four normal strength and high strength concrete beams. Spalling predictions from the model are compared with the measured values of spalling at various stages of fire exposure. The validated model is applied to investigate the influence of fire scenario, concrete strength (permeability) and axial restraint on the fire induced spalling and fire response of RC beams. Results from the analysis show that fire scenario, and concrete permeability largely influence the extent of fire induced spalling in concrete beams. Further, it is also shown that the extent of spalling has significant influence on the fire resistance of RC beams.