Title:
Influence of Load Duration on Shear Strength of Reinforced Concrete Members
Author(s):
Darko Tasevski, Miguel Fernández Ruiz, and Aurelio Muttoni
Publication:
Structural Journal
Volume:
117
Issue:
2
Appears on pages(s):
157-169
Keywords:
critical shear crack theory (CSCT); DIC measurements; experimental tests; loading rate; shear strength; sustained loading
DOI:
10.14359/51721313
Date:
3/1/2020
Abstract:
The significance of sustained loading on the compressive and tensile strength of concrete has been experimentally verified since the 1950s and is currently acknowledged in most design codes implicitly or explicitly. However, its influence on other potentially sensitive phenomena, as for instance the case of members subjected to shear, has not yet been clearly established. Currently, there is still scanty experimental data available on long-term shear tests and they present inconclusive results to assess whether high levels of sustained load have a detrimental effect on the shear strength. To advance on the knowledge of the phenomenon, this manuscript presents the results of an experimental program on 16 reinforced concrete full-scale beams without shear reinforcement tested under varying loading rates (associated to different times to failure, from some seconds to some months). The program consists of two series: one dedicated to slender beams and another to squat members (with different potential significance of the arching action in their shear response). The results show no significant reduction on the shear strength for low loading rates (long times of application of load) in any of the two tests series investigated. Yet, some enhancement is observed in the shear strength for high loading rates (failures in some seconds) compared to typical test durations. The experimental results are analyzed and discussed with reference to refined measurements performed during the tests in terms of crack shape and development. These observations, together with the evaluation of the contributions of the potential shear transfer actions in the specimens, lead to a series of practical design considerations.
Related References:
1. Gilbert, R. I., and Ranzi, G., Time-Dependent Behaviour of Concrete Structures, Spon Press, New York, 2011, 428 pp.
2. Ghali, A.; Favre, R.; and Eldbadry, M., Concrete Structures. Stresses and Deformation: Analysis and Design for Serviceability, third edition, Taylor & Francis, London, UK, 2002, 608 pp.
3. Shank, J. R., “Plastic Flow of Concrete at High Overload,” ACI Journal Proceedings, V. 20, No. 6, June 1949, pp. 493-498.
4. Rüsch, H., “Researches Toward a General Flexural Theory for Structural Concrete,” ACI Journal Proceedings, V. 57, No. 1, Jan. 1960, pp. 1-28.
5. Tasevski, D.; Fernández Ruiz, M.; and Muttoni, A., “Compressive Strength and Deformation Capacity of Concrete under Sustained Loading and Low Stress Rates,” Journal of Advanced Concrete Technology, V. 16, No. 8, 2018, pp. 396-415. doi: 10.3151/jact.16.396
6. Tasevski, D.; Fernández Ruiz, M.; and Muttoni, A., “Assessing the Compressive Strength of Concrete under Sustained Actions: From Refined Models to Simple Design Expressions,” Structural Concrete, V. 20, No. 3, 2019, pp. 971-985. doi: 10.1002/suco.201800303
7. Fischer, I.; Pichler, B.; Lach, E.; Terner, C.; Barraud, E.; and Britz, F., “Compressive Strength of Cement Paste as a Function of Loading Rate: Experiments and Engineering Mechanics Analysis,” Cement and Concrete Research, V. 58, 2014, pp. 186-200. doi: 10.1016/j.cemconres.2014.01.013
8. Müller, H. S. et al., “Time-Dependent Behaviour of Ultra High Performance Concrete (UHPC),” 3rd International fib Congress, Washington, 2010, pp. 1-15.
9. fib International Federation of Structural Concrete, “Bulletin 57: Shear and punching shear in RC and FRC elements,” Ernst and Sohn, Berlin, Germany, 2010, 262 pp.
10. Zsutty, T. C., “Beam Shear Strength Prediction by Analysis of Existing Data,” ACI Journal Proceedings, V. 65, No. 11, Nov. 1968, pp. 943-951.
11. Cavagnis, F.; Fernández Ruiz, M.; and Muttoni, A., “Shear Failures in Reinforced Concrete Members without Transverse Reinforcement: An Analysis of the Critical Shear Crack Development on the Basis of Test Results,” Engineering Structures, V. 103, 2015, pp. 157-173. doi: 10.1016/j.engstruct.2015.09.015
12. Huber, P.; Huber, T.; and Kollegger, J., “Investigation of the Shear Behavior of RC Beams on the Basis of Measured Crack Kinematics,” Engineering Structures, V. 113, 2016, pp. 41-58. doi: 10.1016/j.engstruct.2016.01.025
13. Cavagnis, F.; Fernández Ruiz, M.; and Muttoni, A., “An Analysis of the Shear-Transfer Actions in Reinforced Concrete Members without Transverse Reinforcement Based on Refined Experimental Measurements,” Structural Concrete, V. 19, No. 1, 2018, pp. 49-64. doi: 10.1002/suco.201700145
14. Sarkhosh, R., “Shear Resistance of Reinforced Concrete Beams without Shear Reinforcement under Sustained Loading,” PhD Thesis, TU Delft, Delft, the Netherlands, 2014, 259 pp.
15. Sarkhosh, R., “Shear Capacity of Concrete Beams under Sustained Loading,” International IABSE Conference, Rotterdam, the Netherlands, 2013, pp. 1-8.
16. Muttoni, A., and Fernández Ruiz, M., “Shear Strength of Members without Transverse Reinforcement as Function of Critical Shear Crack Width,” ACI Structural Journal, V. 105, No. 2, Mar.-Apr. 2008, pp. 163-172.
17. Cavagnis, F.; Fernández Ruiz, M.; and Muttoni, A., “A Mechanical Model for Failures in Shear of Members without Transverse Reinforcement Based on Development of a Critical Shear Crack,” Engineering Structures, V. 157, 2018, pp. 300-315. doi: 10.1016/j.engstruct.2017.12.004
18. Fernández Ruiz, M.; Muttoni, A.; and Sagaseta, J., “Shear Strength of Concrete Members without Transverse Reinforcement: A Mechanical Approach to Consistently Account for Size and Strain Effects,” Engineering Structures, V. 99, 2015, pp. 360-372. doi: 10.1016/j.engstruct.2015.05.007
19. Saifullah, H. A.; Nakarai, K.; Piseth, V.; Chijiwa, N.; and Maekawa, K., “Shear Creep Failures of Reinforced Concrete Slender Beams without Shear Reinforcement,” ACI Structural Journal, V. 114, No. 6, Nov.-Dec. 2017, pp. 1581-1590. doi: 10.14359/51700916
20. Sagaseta, J., and Vollum, R., “Shear Design of Short-Span Beams,” Magazine of Concrete Research, V. 62, No. 4, 2010, pp. 267-282. doi: 10.1680/macr.2010.62.4.267
21. Maekawa, K.; Zhu, X.; Chijiwa, N.; and Tanabe, S., “Mechanism of Long-Term Excessive Deformation and Delayed Shear Failure of Underground RC Box Culverts,” Journal of Advanced Concrete Technology, V. 14, No. 5, 2016, pp. 183-204. doi: 10.3151/jact.14.183
22. Bugalia, N., and Maekawa, K., “Time-Dependent Capacity of Large Scale Deep Beams under Sustained Loads,” Journal of Advanced Concrete Technology, V. 15, No. 7, 2017, pp. 314-327. doi: 10.3151/jact.15.314
23. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” American Concrete Institute, Farmington Hills, MI, 2014, 520 pp.
24. CEN European Committee for Standardization, “Eurocode 2. Design of Concrete Structures – General Rules and Rules for Buildings (EN 1992-1-1),” Brussels, Belgium, 2004, 225 pp.
25. fib International Federation of Structural Concrete, “Model Code for Concrete Structures 2010,” Ernst and Sohn, Berlin, Germany, 2013, 434 pp.
26. SIA Swiss Society of Engineers and Architects, “Code 262 for Concrete Structures,” Zürich, Switzerland, 2013, 102 pp.
27. CorrelatedSolutions, VIC3D-8 Manual, www.correlatedsolutions.com, 2017, 114 pp.
28. Campana, S.; Fernández Ruiz, M.; Anastasi, A.; and Muttoni, A., “Analysis of Shear-Transfer Actions on One-Way RC Members Based on Measured Cracking Pattern and Failure Kinematics,” Magazine of Concrete Research, V. 65, No. 6, 2013, pp. 386-404. doi: 10.1680/macr.12.00142
29. Cavagnis, F., “Shear in Reinforced Concrete without Transverse Reinforcement: From Refined Experimental Measurements to Mechanical Models,” PhD thesis, EPFL, Lausanne, Switzerland, 2017, 201 pp.
30. Das Adhikary, S.; Li, B.; and Fujikake, K., “Effects of High Loading Rate on Reinforced Concrete Beams,” ACI Structural Journal, V. 111, No. 3, May-June 2014, pp. 651-660. doi: 10.14359/51686579
31. fib International Federation of Structural Concrete, “Bulletin 42: Constitutive Model for High Strength/High Performance Concrete,” Ernst and Sohn, Berlin, Germany, 2008, 130 pp.
32. Muttoni, A.; Fernández Ruiz, M.; and Niketić, F., “Design versus Assessment of Concrete Structures Using Stress Fields and Strut-and-Tie Models,” ACI Structural Journal, V. 112, No. 5, Sept.-Oct. 2015, pp. 605-616. doi: 10.14359/51687710
33. Fernández Ruiz, M., and Muttoni, A., “On Development of Suitable Stress Fields for Stuctural Concrete,” ACI Structural Journal, V. 104, No. 4, July-Aug. 2008, pp. 495-502.
34. Simões, J. T.; Faria, D. M. V.; Fernández Ruiz, M.; and Muttoni, A., “Strength of Reinforced Concrete Footings without Transverse Reinforcement According to Limit Analysis,” Engineering Structures, V. 112, 2016, pp. 146-161. doi: 10.1016/j.engstruct.2016.01.010