Title:
Boundary Element Detailing in Special Concrete Structural Walls
Author(s):
Travis S. Welt, Dawn E. Lehman, and James M. LaFave
Publication:
Structural Journal
Volume:
115
Issue:
3
Appears on pages(s):
635-647
Keywords:
boundary elements; confinement; reinforced concrete; seismic design; walls
DOI:
10.14359/51701278
Date:
5/1/2018
Abstract:
Reinforced concrete structural walls are one of the most commonly used lateral force-resisting systems for buildings located in regions of high seismicity. Structural walls are expected to provide significant strength and ductility under cyclic earthquake loading. However, compression failures observed following recent earthquakes and in laboratory testing have resulted in concern by the structural engineering community that wall boundary elements may not be able to sustain significant cyclic demands without significant damage. An experimental research program was undertaken to investigate the response of structural wall boundary elements, with a specific focus on boundary element detailing. The test program was developed as multiple series of tests of rectangular prisms that were intended to simulate the effects of geometry, confining reinforcement, and axial loading on the compressive strength and deformability of boundary elements. Each test series studied key confinement detailing parameters, such as vertical spacing of transverse steel, pattern of bar restraint, and the use of crossties in place of continuous hoops. In addition, impact of loading protocol was also studied. These test results were combined with data from existing test programs to form an extensive database, which was used to evaluate impact of such parameters on the distribution of plasticity and strength loss with respect to various ACI 318-14 detailing requirements. Results indicate that boundary elements tested in axial compression just meeting the minimum ACI 318 requirements exhibit strength and strain capacities that are, on average, 20% and 10% larger than unconfined concrete, respectively. The database was also used to develop new detailing recommendations for the spacing and pattern of confinement needed to achieve larger levels of confined response and deformability.
Related References:
1. 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.
2. Earthquake Engineering Research Institute, “The Mw 8.8 Chile Earthquake of February 2010,” EERI Earthquake Spectra Special Earthquake Report, Oakland, CA, June 2010.
3. Earthquake Engineering Research Institute, “The M 6.3 Christchurch, New Zealand, Earthquake of February 22, 2011,” EERI Earthquake Spectral Special Earthquake Report, Oakland, CA, May 2011.
4. Lowes, L. N.; Lehman, D. E.; Birely, A. C.; Kuchma, D. A.; Marley, K.; and Hart, C. H., “Earthquake Response of Slender Planar Concrete Walls with Modern Detailing,” Engineering Structures, V. 43, 2012, pp. 31-47. doi: 10.1016/j.engstruct.2012.04.040
5. NEEShub, “The Chile Earthquake Database Group,” Network for Earthquake Engineering Simulation (online database). https://nees/org/groups/chileearthquakedatabase.
6. ASCE, “Minimum Design Loads for Buildings and Other Structures (ASCE/SEI 7-10),” American Society of Civil Engineers, Reston, VA, 2010.
7. Welt, T. S., “Detailing for Compression in Reinforced Concrete Wall Boundary Elements: Experiments, Simulations, and Design Recommendations,” PhD dissertation, University of Illinois, Champaign, IL, 2015.
8. Mander, J. B.; Priestley, M. N.; and Park, R., “Observed Stress-Strain Behavior of Confined Concrete,” Journal of Structural Engineering, ASCE, V. 114, No. 8, 1988, pp. 1827-1849. doi: 10.1061/(ASCE)0733-9445(1988)114:8(1827)
9. Minami, N., and Nakachi, T., “Compressive Properties of Panels in Reinforced Concrete Core Walls,” 15th World Conference on Earthquake Engineering, Lisbon, Portugal, 2012.
10. Acevedo, C., “Seismic Vulnerability of Non-Special Boundary Elements of Shear Wall under Axial Force Reversals,” Technical Report, Florida International University, Miami, FL, 2010.
11. Creagh, A.; Acevedo, C.; Moehle, J.; Hassan, W.; and Tanyeri, A., “Seismic Performance of Concrete Special Boundary Element,” Technical Report, The University of Texas at Austin, Austin, TX, 2010.
12. Chrysanidis, T. A., and Tegos, I. A., “The Influence of Tension Strain of Wall Ends to their Resistance Against Lateral Instability for Low-Reinforced Concrete Walls,” 15th World Conference on Earthquake Engineering, Lisbon, Portugal, 2012.
13. Massone, L. M.; Polanco, P.; and Herrera, P., “Experimental and Analytical Response of RC Wall Boundary Elements,” Tenth U.S. National Conference on Earthquake Engineering, Anchorage, AK, 2014.
14. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-11) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2011, 473 pp.
15. Paulay, T., and Priestley, J. N., “Stability of Ductile Structural Walls,” ACI Structural Journal, V. 90, No. 4, July-Aug. 1993, pp. 385-392.
16. Rodriguez, M. E.; Botero, J.; and Villa, J., “Cyclic Stress-Strain Behavior of Reinforcing Steel Including the Effect of Buckling,” Journal of Structural Engineering, ASCE, V. 125, No. 6, 1999, pp. 605-612. doi: 10.1061/(ASCE)0733-9445(1999)125:6(605)