# Seismic Performance of Beam–Column Joints in Seawater Sand Concrete Reinforced with Steel-FRP Composite Bars

## TL;DR

This study examines how steel-FRP composite bars improve the earthquake resistance of concrete structures in marine environments.

## Contribution

The novel contribution is the evaluation of seismic performance of beam–column joints reinforced with steel-FRP composite bars in seawater sand concrete.

## Key findings

- Higher axial compression ratios improve bond strength and limit crack propagation but accelerate degradation.
- Moderate beam reinforcement fiber volumes (e.g., 75%) optimize energy dissipation and crack distribution.
- Column reinforcement fiber volumes enhance crack distribution and ductility.

## Abstract

Steel fiber-reinforced polymer (FRP) composite bars (SFCBs) combine the ductility of steel reinforcement with the corrosion resistance and high strength of FRP, providing stable secondary stiffness that enhances the seismic resistance and safety of seawater sea–sand concrete structures. However, the seismic performance of SFCB-reinforced seawater sea–sand concrete beam–column joints remains underexplored. This study presents pseudo-static tests on SFCB-reinforced beam–column joints with varying column SFCB longitudinal reinforcement fiber volume ratios (64%, 75%, and 84%), beam reinforcement fiber volume ratios (60.9%, 75%, and 86%), and axial compression ratios (0.1 and 0.2). The results indicate that increasing the axial compression ratio enhances nodal shear capacity and bond strength, limits slip, and reduces crack propagation, but also accelerates bearing capacity degradation. Higher column reinforcement fiber volumes improve crack distribution and ductility, while beam reinforcement volume significantly affects energy dissipation and crack distribution, with moderate volumes (e.g., 75%) yielding optimal seismic performance. These findings provide insights for the seismic design of SFCB-composite-reinforced concrete structures in marine environments.