Medina CONTRERAS DANIEL

Reinforcement of Steel Structure Joints Under Compression Forces by Using Carbon Fiber Reinforced Polymers(CFRP)

Takeshi MIYASHITA

The reparation method with Carbon Fiber Reinforcement Polymers (CFRP) in steel joints is proposed due to its low weight, high strength resistance, high elasticity and high anti-corrosive features. However, there is few data on cases where CFRP reinforcement can be applied to steel joints such as the taper length used to even the surface on joints.
 This research focus on CFRP reinforcement on steel joints with different taper slopes on axial compression and tension forces. There were conducted tests under axial tension and compression forces with changes on the taper length from 10:1, 5:1 and 2:1. For compression tests, steel members without joints were tested to confirm the taper change reinforcement effect under axial compression.
 The results on tensile test were as shown below:
1.- The taper length 5:1 case, steel yielding appeared over the fracture point, increasing the maximum strength by 30%.
2.- The taper length 2:1 case, steel yielding appeared but fracture does not appear on the steel, changing the failure mode.
3.- All cases presented peeling over 120 MPa stress range. The taper length 5:1 case, peeling presents near the splice plate zone. However, in taper length slope of 2:1, peeling presents on the taper starting point.
 The results on compression test were as shown below:
1.-Cases reinforced under NEXCO�fs manual guidelines, peeling between the steel and epoxy resin appeared, breaking through the CFS near the taper length.
2.- The case with taper length of 10:1, increased the buckling resistance by 8.2 times.
3.- The case with taper length of 5:1, increased the buckling resistance by 6.8 times.
4.- The case with taper length of 2:1, increased the buckling resistance by 5.7 times.
5.- The case with splice plate and a taper length of 5:1, buckling appeared on the taper starting point. The bucking resistance increased from 3.81 kN, to 47.4 kN, 12.4 times bigger.
6.- The case with splice plate and taper length of 2:1. buckling appeared on the taper starting point. Buckling resistance increased from 5.79 kN, to 54.4 kN, 9.4 times bigger.