numerical model | An-Najah Staff

A Numerical Model for Predicting the Fire Resistance of Reinforced Concrete Beams

Sun, 2014-06-01 12:41 — Monther Dwaikat

Journal Title, Volume, Page:

Cement and Concrete Composites Volume 30, Issue 5, Pages 431–443

Year of Publication:

2008

Link:

http://www.sciencedirect.com/science/article/pii/S095894650700145X

Authors:

M. Dwaikat

Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824-1126, United States

Current Affiliation:

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

[email protected]

V.K.R. Kodur

Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824-1126, United States

Preferred Abstract (Original):

A numerical model, in the form of a computer program, for tracing the behavior of reinforced concrete (RC) beams exposed to fire is presented. The three stages associated with the numerical procedure for evaluating fire resistance of RC beams; namely, fire temperature calculation, thermal analysis and strength analysis, are explained. A simplified approach to account for spalling under fire conditions is incorporated into the model. The use of the computer program for tracing the response of RC beams from the initial pre-loading stage to collapse stage, due to the combined effect of fire and loading, is demonstrated. The validity of the numerical model is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. Through the results of numerical study, it is shown that the type of failure criterion has significant influence on predicting the fire resistance of RC beams.

Performance-Based Fire Safety Design of Reinforced Concrete Beams

Sun, 2014-06-01 12:37 — Monther Dwaikat

Journal Title, Volume, Page:

Journal of Fire Protection Engineering, Vol. 17, No. 3, pp. 293-320

Year of Publication:

2007

Link:

http://jfe.sagepub.com/content/17/4/293.abstract

Authors:

M. Dwaikat

Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824-1126, 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, East Lansing, MI 48824-1126, USA

Preferred Abstract (Original):

A numerical model, in the form of a computer program, is presented for tracing the fire behavior of reinforced concrete (RC) beams over the entire range of loading from pre-fire conditions to collapse under fire. The three stages associated with the analysis of fire resistance; namely, establishing the fire temperature—time development, calculating the heat transfer through the structure from the fire, and the structural analysis are explained. The model, which accounts for nonlinear material properties at elevated temperatures, is capable of predicting the fire resistance of RC beams under realistic fire scenarios, load levels, and failure criteria. The validity of the numerical model is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. Through the results of numerical study, it is shown that the type of failure criterion, load level, and fire scenario have significant influence on fire resistance of RC beams. The computer program can be used to undertake performance-based fire safety design of RC beams for any value of the significant parameters, such as fire exposure, concrete cover thickness, section dimensions, concrete strength, concrete type, and load intensity.

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.

A Numerical Approach for Modeling the Fire Induced Restraint Effects in Reinforced Concrete Beams

Sun, 2014-06-01 10:46 — Monther Dwaikat

Journal Title, Volume, Page:

Fire Safety Journal Volume 43, Issue 4, Pages 291–307

Year of Publication:

2008

Link:

http://www.sciencedirect.com/science/article/pii/S0379711207000938

Authors:

M.B. Dwaikat

Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824-1126, USA

Current Affiliation:

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

[email protected]

V.K.R. Kodur

Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824-1126, USA

Preferred Abstract (Original):

In this paper, a model to predict the influence of fire induced restraints on the fire resistance of reinforced concrete (RC) beams is presented. The three stages, associated with the fire growth, thermal and structural analysis, for the calculation of fire resistance of the RC beams are explained. A simplified approach to account for spalling under fire conditions is incorporated into the model. The validity of the numerical model is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. The program is used to conduct two case studies to investigate the influence of both the rotational and the axial restraint on the fire response of the RC beams. Through these case studies, it is shown that the restraint, both rotational and axial, has significant influence on the fire resistance of the RC beams.

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.