Experimental and Analytical Evaluation of Dowel Action in Ultra-high Performance Concrete

Document Type : Original Research

Authors
A. Khazaee 1
M. Ghalehnovi 2
M. Rakhshanimehr 3
1 Esfarayen Faculty of Industrial and Engineering, Department of Civil Engineering, Esfarayen, North Khorasan, Iran
2 Professor, Ferdowsi University of Mashhad, Mashhad, Iran
3 Department of Civil Engineering, Alzahra University.
10.22034/21.6.1
Abstract
In a reinforced concrete member, especially in a beam, mechanisms of shear transfer are as follows:1. The force created in shear bars after diagonal cracks, 2. The shear capacity of the concrete in a part of the compressive region of the concrete with no crack, 3. The forces from the aggregates interlock at both sides of the crack, 4. The force due to the dowel action of the flexural bars that connect both sides of the crack and create resistance against shear deformation of the crack. Dowel action can be defined as follows: the ability of the longitudinal bars to transfer the force perpendicular to their axis. The distance between the longitudinal axis of the non-deformed parts at both sides of the crack is considered as the deformation of the dowel bar.

To be able to analyze and design the reinforced concrete structure members correctly, their behavior must be evaluated under different loadings. The efficiency, accuracy, and speed of the structure analysis techniques depend on using suitable behavior models. In reinforced concrete structures, the concrete will be cracked under normal loadings due to its weakness in tension. Therefore, it is important to know the mechanisms of stress transfer in the cracked surfaces to evaluate the response of the reinforced concrete structures. In recent years, an extensive experimental and analytical study on the effect of longitudinal bars in shear transferring (dowel action) has done. Almost all the models presented the theory of Beam on Elastic Foundation (BEF) as the best way to simulate the behavior of the dowel action. In this model, the subgrade stiffness of concrete is the most important parameter. BEF model is a linear model because the dowel bar and its surrounding concrete are modeled by a uniaxial element on a row of springs. The advantage of the linear models is that they gather all features of the concrete and the interaction of the concrete-bar in a bearing stiffness coefficient. For this reason, a suitable formulation is required for it to model the beam behavior from the elastic stage to the failure. In the elastic state, the bearing stiffness can be presented as a constant like BEF traditional models. However, in the nonlinear state, the stiffness must be a function of displacement to model the failure due to the load.

In the present research, an experimental program is followed on the beam-type specimens to identify the behavior of the cracked surfaces under the effect of the shear. Using the test specimens made of ultra-high performance concrete, the shear transferred through a longitudinal bar (dowel action) is measured. The shear response of the dowel bar, the subgrade stiffness, and the displacements are measured. Furthermore, suitable formulations are proposed for the UHPC subgrade stiffness. Based on the results of the tests and using the studies of other researchers, a suitable model is presented for the shear mechanism through the bar in the cracked surfaces of ultra-high performance concrete. The results show the suitable precision of the proposed relations to estimate the dowel displacement-shear curve in the specimens with vertical and inclined cracks.

Keywords

Subjects

1. Comité euro-international du béton, 1996. RC elements under cyclic loading: state of the art report (Vol. 230). Thomas Telford.
2. Maitra, S.R., Reddy, K.S. and Ramachandra, L.S., 2009. Load transfer characteristics of dowel bar system in jointed concrete pavement. Journal of Transportation Engineering, 135(11), pp.813-821.
3. Timoshenko, S., 1925. Applied elasticity .Westinghouse Tech. Night Press.
4. Moradi, A., 2013. A universal constitutive model for simulate stress transfer across RC cracks and interfaces under cyclic multiaxial deformations. Tarbiat Modares University: Tehran.(In Persian)
5. Walraven, J.C. and Reinhardt, H.W., 1981. Concrete mechanics. Part A: Theory and experiments on the mechanical behavior of cracks in plain and reinforced concrete subjected to shear loading. STIN, 82, p.25417.
6. Paulay, T., Park, R. and Phillips, M.H., 1974. Horizontal construction joints in cast-in-place reinforced concrete. Special Publication, 42, pp.599-616.
7. Finney, E.A., 1956. Structural design considerations for pavement joints. Journal of the American Concrete Institute, 28(1), pp.1-28.
8. Soroushian, P., Obaseki, K., Rojas, M.C. and Sim, J., 1986, July. Analysis of dowel bars acting against concrete core. In Journal Proceedings (Vol. 83, No. 4, pp. 642-649).
9. Soroushian, P., Obaseki, K. and Rojas, M.C., 1987. Bearing strength and stiffness of concrete under reinforcing bars. Materials Journal, 84(3), pp.179-184.
10. Dei Poli, S., Di Prisco, M. and Gambarova, P.G., 1992. Shear response, deformations, and subgrade stiffness of a dowel bar embedded in concrete. structural Journal, 89(6), pp.665-675.
11. Soltani, M. and Maekawa, K., 2008. Path-dependent mechanical model for deformed reinforcing bars at RC interface under coupled cyclic shear and pullout tension. Engineering structures, 30(4), pp.1079-1091.
12. Dulacska, H., 1972, December. Dowel action of reinforcement crossing cracks in concrete. In Journal Proceedings (Vol. 69, No. 12, pp. 754-757).
13. Moradi, A.R., Soltani, M. and Tasnimi, A.A., 2012. A simplified constitutive model for dowel action across RC cracks. Journal of advanced concrete technology, 10(8), pp.264-277.
14. Moradi, A.R., Soltani, M. and Tasnimi, A.A., 2015. Stress-transfer behavior of reinforced concrete cracks and interfaces. ACI Structural Journal, 112(1), p.69.
15. Maekawa, K. and Qureshi, J., 1996. Embedded bar behavior in concrete under combined axial pullout and transverse displacement. Doboku Gakkai Ronbunshu, 1996(532), pp.183-195.
16. Maekawa, K. and Qureshi, J., 1996. Computational model for reinforcing bar embedded in concrete under combined axial pullout and transverse displacement. Doboku Gakkai Ronbunshu, 1996(538), pp.227-239.
17. Figueira, D., Sousa, C. and Serra Neves, A., 2018. Winkler spring behavior in FE analyses of dowel action in statically loaded RC cracks. Computers and Concrete, 21(5), pp.593-605.
18. Li, P., Tan, N. and Wang, C., 2018. Nonlinear Bond Model for the Dowel Action considering the Fatigue Damage Effect. Advances in Materials Science and Engineering, 2018.
19.Kottari, A., Mavros, M., Murcia-Delso, J. and Shing, P.B., 2017. Interface model for bond-slip and dowel-action behavior. ACI Structural Journal, 114(4), pp.1043-1053.
20.Filatov, V.B., 2018, December. Experimental Investigation Dowel Action of Longitudinal Reinforcement of Reinforced Concrete Beams. In IOP Conference Series: Materials Science and Engineering (Vol. 463, No. 4, p. 042005). IOP Publishing.
21. Rahdar, H.A. and Ghalehnovi, M., 2016. Post-cracking behavior of UHPC on the concrete members reinforced by steel rebar. Computers and Concrete, 18(1), pp.139-154.
22. Pruijssers, A.F., 1990. Aggregate interlock and dowel action under monotonic and cyclic loading.
23. Khazaee, A. and Ghalehnovi, M., 2018. Bearing stiffness of UHPC; an experimental investigation and a comparative study of regression and SVR-ABC models. Journal of Advanced Concrete Technology, 16(3), pp.145-158..
24. Soltani, M., An, X. and Maekawa, K., 2003. Computational model for post cracking analysis of RC membrane elements based on local stress–strain characteristics. Engineering structures, 25(8), pp.993-1007.
Modares Civil Engineering journal
Volume 21, Issue 6
November and December 2021
Pages 7-23