Highly Damage-Tolerant Beam-Column Joints Through Use of High-Performance Fiber-Reinforced Cement Composites

• Published in: ACI structural journal Vol. 102; no. 3; pp. 487 - 495
• Main Authors: Parra-Montesinos, Gustavo J, Peterfreund, Sean W, Chao, Shih-Ho
• Format: Journal Article
• Language: English
• Published: Farmington Hills American Concrete Institute 01.05.2005
• Subjects: Cement; Concrete; Feasibility studies; Fiber reinforced composites; Joint strength; Seismology; Shear strength
• ISSN: 0889-3241; 1944-7361
• DOI: 10.14359/14421

The feasibility of using high-performance fiber-reinforced cement composites (HPFRCCs) as a means to eliminate the need for confinement (transverse) reinforcement and the associated construction problems in beam-column connections subjected to earthquake-induced loading is evaluated. The fiber cementitious material used in this study contained ultra-high molecular weight polyethylene fibers in a 1.5% volume fraction, which represented the minimum value for which a tensile strain-hardening behavior was obtained from direct tension tests. Two large-scale subassemblies, consisting of beams framing into a column from two opposite sides, were tested under displacement reversals to evaluate the adequacy of the proposed connection design for use in zones of high seismicity. The two HPFRCC connections were subjected to peak shear stresses of 7.3 and 9.3 MPa, which corresponded to approximately 1.2 and 1.4[radical] f'^sub c^ (MPa), respectively. Although the maximum beam shear stress corresponded to 0.2[radical] f'^sub c^ (MPa), no special transverse reinforcement detailing was provided in the beam plastic hinge regions. Experimental results indicate that HPFRCC beam-column connections perform satisfactorily under large shear reversals with excellent damage tolerance. The test specimens sustained drifts as large as 5.0% with beam rotation capacities in the order of 0.04 rad. Only minor joint damage was observed at the end of the tests, indicating that the ACI joint shear stress limit of 5/4[radical] f'^sub c^ (MPa) can be safely used in HPFRCC connections with no confinement reinforcement. Also, excellent bond between beam longitudinal bars and surrounding HPFRCC material was observed throughout the tests even though the connection design did not satisfy minimum anchorage length requirements specified in the ACI Building Code. [PUBLICATION ABSTRACT]