concrete beams | 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.

Response of Restrained Concrete Beams under Design Fire Exposure

Sun, 2014-06-01 09:25 — Monther Dwaikat

Journal Title, Volume, Page:

ASCE Journal of Structural Engineering, Vol. 135, No. 11, pp. 1408-1417

Year of Publication:

2009

Link:

http://ascelibrary.org/doi/abs/10.1061/(ASCE)ST.1943-541X.0000058

Authors:

M. B. Dwaikat

Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Michigan State Univ., MI 48824

Current Affiliation:

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

[email protected]

V. K. R. Kodur

Professor, Dept. of Civil and Environmental Engineering, Michigan State Univ., MI 48824

Preferred Abstract (Original):

Results from fire resistance experiments on six RC beams are presented in this paper. The test variables included concrete strength (permeability), support conditions, fire scenario, and load ratio. Data from fire tests are used to illustrate the comparative performance of high strength concrete (HSC) and normal strength concrete (NSC) beams under fire conditions. Also, data from the tests is used to validate a macroscopic finite-element model specifically developed for tracing the fire response of RC beams. Results from the tests and numerical studies show that HSC beams have lower fire resistance than that of NSC beams. It is also shown that HSC beams exhibit higher levels of spalling which is largely influenced by the permeability of concrete, type of fire exposure, load level, and restraint conditions. Similarly, the type of fire scenario, axial restraint, and load level have significant influence on the overall fire resistance of RC beams. These factors are to be considered for evaluating the fire resistance of RC beams under fire conditions.

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.