ガス圧接継手の抜取検査試験片の引張試験結果に関する調査研究 : 仙台市における調査

抄録

During 10 years (1976-1985), 5302 Gas pressure welded joints which sampled regarding tensile test were tested at Tohoku Institute of Technology. These test pieces were sampled accoarding to the methods based on Standard Specification for Gas Pressure Welding of Reinforcing Bars (established by Japan Pressure Welding Society) and Japanese Industrial Standard (JIS Z 3120). In the above test pieces, the kind of reinforcing bars were SD 30 and SD 35, thire nominal diameters were from D 19 to D 29. In this report, the raito of the pressure welded part failure and distribution of thire strength on the above test piecces were investigated. The investigated results obtained were as follows. 1. In Gas pressure welded joints, pressure welded part failure was exsisted. But in this time of investigation from the whole 5302 tested pieces, the failured pressure welded parts were 20 pieces which had a ratio of 0.38 %. 2. From 1976 to 1985 during recent 6 years, the distribution ratio of the pressure welded part failure was at the range from 0 to 0.33 %. It was lower than the average ratio 0.38 % of pressure welded part failures. It shows somewhat little tendency of pressure welded part failure in recent years. 3. No distinct tendency was observed between the rations of preesure welded part failure, temprature (monthly average temprature is distributed from 0.7 ℃ to 38 ℃) and amount of precipitation (monthly average precipitation is distrbuted from 22 mm to 196 mm) of Sendai city. 4. The ratio of pressure welded part failure of SD 30 and SD 35 was 0.38 % and 0.37 %, almost equal. There was no specific tendency observed between the kind of reinforcing bars and ratios of pressure welded parts failure. 5. Regarding the range of reinforcing bars diameter of D 19 to D 29, in the case of SD 30 certainly the reinforcing bars diameter is becoming large, the pressere welded parts failure was observed with high ratio. 6. In the whole 5302 tested pieces, only one piece in SD 35 falured before yield, the failure ratio was 0.02 %. There was no any failure bars before yield in SD 30. Morever, the maximum strength of the pressure welded parts failured pieces was 3659 kg/cm^2 and this cleared the JIS standard yield strength. 7. There were 3 pieces in SD 30 and 4 pieces in SD 35 among the tested pressure welded parts failure which decreased JIS standard tensile strength. Thier ratio of decrease of JIS standard tensile strength was 0.13 %. 8. The average value of the strength rising ratios after yield of the tested pressure welded parts failure, in SD 30 and SD 35 were 1.44 and 1.37, respectively. It was higher in case of SD 30 than SD 35.