Papers by Author: Zhen Hua Ren

Abstract: Rehabilitation of existing structures with fiber reinforced plastics (FRP) has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high stiffness-to-weight ratio. This paper presents strain coordination results of (two groups)15 reinforced concrete beams strengthened with different methods including external-bonded and near-surface mounted carbon FRP strip in order to investigate the strain coordination of CFRP and steel rebar of RC beam. Because there is relative slipping between RC beam and CFRP, the strain of CFRP and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiber that parallels to the neutral axis of plated beam within the scope of effective height (h₀) of the cross section is in direct proportion to the distance from the fiber to the neutral axis, the strain of FRP and steel rebar satisfies the equation: , the value of is equal to 1.1~1.3 according to the test results.

Abstract: Guangxi province is the typical expansive soil area, and the unconfined compressive strength is the important strength index. There is little studied result about the unconfined compressive strength of expansive soil in Guangxi province. Based on the expansive clay experimental embankment of Nanyou Highway, the experimental research on the unconfined compressive strength was undertaken. Tests results indicate that the expansive clay samples are all disintegrated when the sample is dip in water, which show that the stability of expansive clay is very weak. Some lime improving samples of curling 7 days and 14 days are also disintegrated when dipping in water, which indicate that the unconfined compressive strength sample of lime improving expansive clay should curl 28 days. Lime ratio and curing time both influence the unconfined compressive strength of improving expansive clay greatly. There is optimum adding lime ratio for lime improving expansive clay. During the early days of curing the unconfined compressive strength have linear increase with curing time.

Abstract: Rehabilitation of existing structures with fiber reinforced plastics (FRP) has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high stiffness-to-weight ratio. This paper presents strain coordination results of (two groups)6 reinforced concrete beams strengthened with different methods including near-surface mounted CFRP bar and helical rib rebar in order to investigate the strain coordination of CFRP bar or HR bar and steel rebar of RC beam. Because there is relative slipping between RC beam and bar, the strain of CFRP or HR bar and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiber that parallels to the neutral axis of plated beam within the scope of effective height (h₀) of the cross section is in direct proportion to the distance from the fiber to the neutral axis, the strain of CFRP or HR and steel rebar satisfies the equation: ε_CH=βε_steel , the value of β is equal to 1.0～1.2 according to the test results.