Pilot Demonstration of a Strengthening Method for Steel-Bolted Connections Using Pre-Formable Carbon Fiber Cloth with...

Area of Science:

• Structural Engineering
• Materials Science
• Seismic Retrofitting

Background:

• Steel structures commonly use slender seismic braces, requiring robust connections for energy absorption.
• Existing brace connections may not meet the full plastic axial tension load requirements.
• Carbon fiber reinforced plastic (CFRP) is a high-strength, lightweight material increasingly used for structural strengthening.

Purpose of the Study:

• To investigate the effectiveness of CFRP strengthening for seismic brace connections and gusset plates.
• To evaluate the application of CFRP on stepped surfaces for improved stress transfer.
• To demonstrate the use of vacuum-assisted resin transfer molding for CFRP application.

Main Methods:

• Application of CFRP layers to brace connections and gusset plates with stepped surfaces.
• Utilizing vacuum-assisted resin transfer molding (VARTM) for CFRP impregnation and curing.
• Analysis of stress transfer and performance of strengthened components.

Main Results:

• CFRP strengthening successfully improved the connection strength of seismic braces.
• Enhanced plastic deformation capacity was observed, reaching 3% elongation.
• The technique proved effective even when CFRP was molded on stepped surfaces, eliminating the need for surface modification.

Conclusions:

• CFRP strengthening is a viable method to enhance the seismic performance of steel brace connections.
• The VARTM technique is suitable for applying CFRP to complex geometries like stepped surfaces.
• This approach offers a promising solution for improving the resilience of existing steel structures against seismic events.