NUMERICAL METHOD FOR PREDICTING FIRST CRACK LOAD ON HOLLOW-CORED BEAMS SUBJECTED TO POINT LOAD AT MIDSPAN

Uche Kingsley Ogbonna; O. U. Orie

doi:10.4314/njt.v43i1.6

Authors

U. K. Ogbonna Department of Civil Engineering, University of Benin, Edo State, Nigeria
O. U. Orie Department of Civil Engineering, University of Benin, Edo State, Nigeria

DOI:

https://doi.org/10.4314/njt.v43i1.6

Keywords:

Numerical method, hollow cored beams, modulus of rupture, first crack load, Moment of Inertia

Abstract

Predicting the initial crack load in concrete is important to detect early warning of a problem. In this study, a model for predicting the first crack load on a hollow-cored rectangular beam point loaded at mid-span was developed by combining a numerical method and an experimental approach. The modulus of rupture was introduced into the governing moment-curvature relationship. Experimentally, flexural testing with point loads at mid-span was performed on fifteen (15) beams made up of three (3) beam types at 1 kN intervals for a span of 750mm using the Universal Testing machine. The beams were simply supported by roller points. The dimensions of the beams were kept constant and later varied while investigating the following hollow diameters: 0, 30, 60, 75, and 105mm. Numerically, the beams were designed as a beam element point loaded at mid-span with a span of 700mm centers, and the support conditions were defined as pinned support. Governing equations relating failure load with the modulus of rupture, stiffness matrix, shape functions, and moment of inertia were developed. The equation for predicting the first crack load, incorporating the modulus of rupture, was derived. The moment of inertia was calculated by discretizing the hollow-cored beam section using an isoparametric geometric transformation. The experimental results were used to validate the numerical model. 90.55% agreement between experimental and numerical results was observed. The overall average percentage difference between the two methods recorded is 9.45%. This shows that at about 91% confidence level, both approaches are the same and can be applied with confidence in the prediction of the first crack load on hollow-cored reinforced concrete beams.

References

Orie, O. E., and Idolor, B. “Optimizing Compression Zone Of Flanged Hollow Cored Concrete Beams Using Moment Of Inertia Theory”, Nigerian Journal of Technology (NIJOTECH). Vol. 34, Issue 2, pp. 217 – 222, 2015.

Gund, A., and Pati, A. “Fracture Analysis Of Reinforced Concrete Beam”, International Research Journal of Engineering and Technology (IRJET), Volume: 07 Issue, pp. 186-190, 2020.

Chaudhari, S. V., and Chakrabarti, M. A. “Modeling of concrete for nonlinear analysis Using Finite Element Code ABAQUS”, International Journal of Computer Applications, Vol. 44, No.7, 2012, pp. 14-18.

Orie, O. E., and Idolor, B. “Optimizing Compression Zone Of Flanged Hollow Cored Concrete Beams Using Moment Of Inertia Theory”, Nigerian Journal of Technology (NIJOTECH), Vol. 34, Issue 2, 2015, pp. 217 – 222.

Daud, S. A., Daud, R. A., and Al-Azzawi, A. A. “Behavior of reinforced concrete solid and hollow beams that have additional reinforcement in the constant moment zone”, Ain Shams Engineering Journal, Vol.12, Issue 1, 2021, pp 31-36.

Saoul, A., Meftah, S. A., Mohri, F., and Daya, E. M. “Lateral buckling of box beam elements under combined axial and bending loads”, Journal of Constructional Steel Research, Vol.116, pp. 2016,141-155.

Soji, S., and Anima, P. “Experimental and Analytical Investigation on Partial Replacem-ent of Concrete in the Tension Zone”, International Journal of Engineering Research and General Science, Vol. 4, Issue 4, 2016,pp. 23-32.

Al-Qasem, I., Hasan, A. R., Abdulwahid, M. Y., and Galobardes, I. “Comparison between Analytical Equation and Numerical Methods for Determining Shear Stress in a Cantilever Beam”, Civil Engineering Journal, Vol. 4, Issue 2, 2018, pp.258-265.

Orie, O. U., and Ogbonna, U. K. “Flexural Characteristics of Hollow Cored Rectangular plain Concrete Beams Using Finite Element Approach”, Journal of the Nigerian

Association of Mathematical Physics, Vol.62 Oct -Dec., 2021 Issue, 2021 pp147-152.”

Concrete Mix Design Manual First Edition: Council for the Regulation of Engineering in Nigeria, special Publication; No. Coren/2017/0 16/RC, August 2017.

NIS444-1. Composition, Specification, and

Conformity Criteria for Common Cements,

Standard Organization of Nigeria, Lagos, 2014.

British Standards Institution, BS 1881 part 109. “Specifications for Concrete Moulds”, British Standards House, London, 1983.

BS 8110 part 2-Code of Practice for special circumstances

Mosley, W. H., and Bungey, J. H. Macmillan Education Ltd Reinforced Concrete Design, 1990.

Novak, D., Bazant, Z. P., and Vitek, J. l. “Experimental - Analytical size - Dependent Prediction of Modulus Of Rupture of concrete”, Non-traditional cement and concrete, 2002, pp.387-393.

Bharikatti, S. S. “Finite Element analysis”, 1st edition, New age international (P) ltd., New Delhi, India, 2005.

Onyeka, F. C., Okeke, E. T., and Wasiu, J. “Strain–Displacement Expressions and their Effect on the Deflection and Strength of Plate”, Advances in Science, Technology and Engineering Systems, 5(5), 2020, pp 401-413.