The increasing demand for earthquake-resistant structures has accelerated the development of innovative construction materials capable of providing enhanced strength, durability, and ductility under severe seismic loading. Link beams are one of the most critical structural components in coupled shear wall systems because they transfer shear forces between adjacent walls while dissipating seismic energy through controlled inelastic deformation. Conventional reinforced concrete (RC) link beams often suffer from excessive diagonal cracking, reinforcement congestion, concrete crushing, and premature failure when subjected to repeated cyclic loading during strong earthquakes.

Ultra-High-Performance Concrete (UHPC), characterized by its compressive strength exceeding 150 MPa, tensile strain-hardening behavior, and exceptional durability, offers a promising solution to these limitations. The incorporation of distributed steel fibers within the UHPC matrix significantly enhances crack resistance, energy absorption, ductility, and post-cracking strength. This study investigates the seismic behavior of steel fiber-reinforced UHPC link beams through nonlinear finite element analysis under cyclic loading.

A three-dimensional finite element model is developed using ABAQUS, where concrete damage plasticity (CDP) is employed to simulate UHPC behavior and embedded truss elements represent steel reinforcement. Different steel fiber volume fractions (0%, 1%, 1.5%, and 2%) are examined to evaluate their influence on structural performance. Representative (illustrative) simulation outputs—including stress contours, crack patterns, hysteresis loops, stiffness degradation, and energy dissipation curves—are analyzed to compare the seismic performance of various beam configurations.

 

The numerical investigation indicates that increasing steel fiber content significantly delays crack propagation, improves stiffness retention, increases ductility, and enhances energy dissipation capacity. UHPC link beams with 2% steel fibers exhibit superior seismic resilience compared with conventional reinforced concrete link beams. The findings demonstrate the potential of UHPC link beams as a reliable structural solution for high-rise buildings, nuclear facilities, bridges, and other critical infrastructure located in earthquake-prone regions.

Keywords: Ultra-High-Performance Concrete, UHPC, Steel Fibers, Link Beam, Earthquake Engineering, ABAQUS, Finite Element Analysis, Cyclic Loading, Seismic Performance, Concrete Damage Plasticity