Title:
Analysis and Design of Double-Beam Coupling Beams
Author(s):
Youngjae Choi and Shih-Ho Chao
Publication:
Structural Journal
Volume:
117
Issue:
5
Appears on pages(s):
79-95
Keywords:
coupled wall systems; diagonally reinforced coupling beams; double-beam coupling beams (DBCB); interface shear strength
DOI:
10.14359/51725985
Date:
9/1/2020
Abstract:
Double-beam coupling beams (DBCBs) are a viable alternative to diagonally reinforced concrete coupling beams (DCBs). While construction time and effort of DBCBs is much less than DCBs, their ability to sustain strong earthquake forces was also experimentally proven to be equivalent to DCBs. DBCBs consist of two slender reinforced concrete beams with an unreinforced concrete strip (UCS) between them. A DBCB gradually splits into two slender beams from small to large displacements, thereby transitioning from a brittle shear mechanism to a ductile flexural mechanism. This paper presents a recommended design procedure for DBCBs based on previous experimental results. An additional specimen was designed based on the design recommendation and tested under the same displacement protocol. The specimen showed satisfactory seismic performance with ductile behavior up to 6% beam chord rotation. One of the major advantages of DBCBs is they allow utility ducts such as polyvinyl chloride (PVC) pipes to pass through the coupling beams at the UCS. Experimental testing and nonlinear finite-element analyses reveal that the location of the utility ducts can have a significant effect on the behavior of DBCBs. Research results suggest that these utility ducts should be placed at the ends of the UCS. Prior experimental testing indicated that when the span-depth ratio ln/h of a DBCB becomes smaller, the load-versus-
beam chord rotation response exhibits a pinched shape due to the greater influence of shear cracks. This pinching effect was investigated by nonlinear time-history (NTH) analyses on a 42-story coupled wall system subjected to both design-basis earthquakes and maximum-considered earthquakes. A hybrid model for DBCBs considering shear, flexure, and pinching was developed. The NTH analyses show that the seismic performance in terms of peak interstory drift ratios is nearly identical between DBCBs and DCBs; therefore, no evidence indicates pinching having an appreciable effect.
Related References:
ACI Committee 318, 2019, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19),” Farmington Hills, MI, 624 pp.
Barney, G. B.; Shiu, K. N.; Rabbat, B. G.; Fiorato, A. E.; Russell, H. G.; and Corley, W. G., 1980, “Behavior of Coupling Beams Under Load Reversals (RD068.01B),” Portland Cement Association, Skokie, IL.
Choi, Y.; Hajyalikhani, P.; and Chao, S.-H., 2018, “Seismic Performance of Innovative RC Coupling Beam—Double-Beam Coupling Beam,” ACI Structural Journal, V. 115, No. 1., Jan., pp. 113-125. doi: 10.14359/51700951
CSI (Computers and Structures), 2006, “PERFORM-3D – Nonlinear Analysis and Performance Assessment for 3D-Structures,” User Guide, V4, Berkeley, CA.
Foutch, D. A., and Shi, S., 1998, “Effects of Hysteresis Type on the Seismic Response of Buildings,” Proceedings of the Sixth U.S. National Conference on Earthquake Engineering, Seattle, WA, Earthquake Engineering Research Institute, Oakland, CA.
Gupta, A., and Krawinkler, H., 1998, “Effect of Stiffness Degradation on Deformation Demands for SDOF and MDOF Structures,” Proceedings of the 6th U.S. National Conference on Earthquake Engineering, Seattle, WA.
Gupta, B., and Kunnath, S., 1998, “Effect of Hysteretic Model Parameters on Inelastic Seismic Demands,” Proceedings of the 6th U.S. National Conference on Earthquake Engineering, Seattle, WA.
Harries, K. A.; Fortney, P. J.; Shahrooz, B. M.; and Brienen, P. J., 2005, “Practical Design of Diagonally Reinforced Concrete Coupling Beams – Critical Review of ACI 318 Requirements,” ACI Structural Journal, V. 102, No. 6, Nov.-Dec., pp. 876-882.
Hooper, J. D., 2014, “Couplings – Current Practice, Issues, and Opportunities,” ID ORAL20D, Tenth U.S. National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Anchorage, AK, July 21-25.
Lim, E.; Hwang, S. J.; Cheng, C. H.; and Lin, P. Y., 2016, “Cyclic Tests of Reinforced Concrete Coupling Beam with Intermediate Span-Depth Ratio,” ACI Structural Journal, V. 113, No. 3, May-June, pp. 515-524. doi: 10.14359/51688473
Medina, R., 2002, “Seismic Demands for Nondeteriorating Frame Structures and their Dependence on Ground Motions” PhD dissertation, Department of Civil and Environmental Engineering, Stanford University, Stanford, CA.
Medina, R., and Krawinkler, H., 2004, “Influence of Hysteretic Behavior on the Nonlinear Response of Frame Structures,” Proceedings of the 13th World Conference on Earthquake Engineering, Vancouver, BC, Canada.
Moehle, J.; Bozorgnia, Y.; Jayaram, N.; Jones, P.; Rahnama, M.; Shome, N.; Tuna, Z.; Wallace, J.; Yang, T.; and Zareian, F., 2011, “Case Studies of the Seismic Performance of Tall Buildings Designed by Alternative Means,” Task 12 Report for the Tall Buildings Initiative, Pacific Earthquake Engineering Research Center, Report No. 2011/05, July.
Naish, D.; Fry, J. A.; Klemencic, R.; and Wallace, J., 2013a, “Reinforced Concrete Coupling Beams—Part I: Testing,” ACI Structural Journal, V. 110, No. 6, Nov.-Dec., pp. 1057-1066.
Naish, D.; Fry, J. A.; Klemencic, R.; and Wallace, J., 2013b, “Reinforced Concrete Coupling Beams—Part II: Modeling,” ACI Structural Journal, V. 110, No. 6, Nov.-Dec., pp. 1067-1075.
Nassar, A. A., and Krawinkler, H., 1991, “Seismic Demands for SDOF and MDOF Systems,” Report No. 95, John A. Blume Earthquake Engineering Center, Stanford University, Stanford, CA.
Park, P., and Paulay, T., Reinforced Concrete Structures, John Wiley & Sons, Inc., New York, 1975, 769 pp.
Paulay, T., and Priestley, M. J. N., 1992, Seismic Design of Reinforced Concrete and Masonry Buildings, John Wiley and Sons Inc., New York, 768 pp.
Rahnama, M., and Krawinkler, H., 1993, “Effects of Soft Soil and Hysteretic Models on Seismic Demands,” Report No. 108, John A. Blume Earthquake Engineering Center, Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, 258 pp.
Ruiz-García, J., and Miranda, E., 2003, “Inelastic Displacement Ratio for Evaluation of Existing Structures,” Earthquake Engineering & Structural Dynamics, V. 32, No. 8, pp. 1237-1258. doi: 10.1002/eqe.271
Shi, S., and Foutch, D. A., 1997, “Evaluation of Connection Fracture and Hysteresis Type on the Seismic Response of Steel Buildings,” Report No. 617, Civil Engineering Studies, Structural Research Series, University of Illinois at Urbana-Champaign, Urbana, IL.
StructurePoint, 2018, spColumn User Manual, v6.50.
Wong, P. S., and Vecchio, F. J., 2002, VecTor2 & Formworks User’s Manual.