擴頭鋼筋單體受拉之力學特徵與試驗裝置開發

Mechanical Characteristics and Testing Device Development of Headed Reinforcements for Uniaxial Tension Test

林克強(Ker-Chun Lin) ； 歐宸宇(Chen-Yu Ou) ； 紀凱甯(Kai-Ning Chi) ； 莊勝智(Sheng-Jhih Jhuang) ； 廖文義(Wen-I Liao)

《結構工程》 38卷1期 (2023/03) Pp. 63-84

https://doi.org/10.6849/SE.202303_38(1).0003

摘要

本文主要目的在探討台灣常用擴頭鋼筋之單體試件受拉的力學特徵，並開發符合時間效益的試驗裝置。本研究進行四種鋼筋強度等級（SD 420W、SD 490W、SD 550W與SD 690）共41組之擴頭鋼筋單體受拉試驗，擴頭部包括摩擦銲、銲接螺桿、擴頭滾牙與螺紋套筒灌漿等型式。試驗之滑動量結果顯示，試驗採用0.7P_y與0.95P_y為加載上限值，可獲得相同的合格與否鑑識結果，其中P_y為鋼筋最小規定降伏強度。摩擦銲式擴頭鋼筋幾乎無滑動量。其餘滑動量由小至大分別為：限滑擴頭滾牙式、螺桿銲接式、擴頭滾牙式、與螺紋套筒灌漿式擴頭部，其中，非螺紋套筒灌漿式擴頭部之滑動量均不大於0.2 mm。對於螺紋套筒灌漿式擴頭鋼筋，有限制滑動裝置者，只要採用適當限滑裝置且施工適當時，其滑動量多能控制在0.3 mm內；無限制滑動裝置者，其滑動量均大於0.3 mm。本研究之強度試驗結果顯示，所有試體的最大強度均能發展鋼筋規定降伏強度的1.25倍與規定抗拉強度。本研究開發完成之擴頭鋼筋單體試件拉力試驗裝置能迅速並目視架設量測設備，以獲得準確的擴頭部滑動量，且較原試驗裝置可縮短約78%的試驗時間，該試驗裝置測試目標上限為SD 690之#12擴頭鋼筋。

關鍵字

擴頭鋼筋 ； 擴頭鋼筋單體試件拉力試驗裝置 ； 擴頭部滑動量 ； 伸長率 ； 拉力強度

並列摘要

This paper mainly investigates mechanical characteristics of headed reinforcements in tension popular used in Taiwan and develops a fixture for testing to effectively shorten test time. A total of 41 headed reinforcement specimens that include four types of steel grade, SD 420W、 SD 490W、 SD 550W and SD 690, and three main types of head part, welded head, threaded head, grouted sleeve head. Test results related to head part slip showed that upper loading bounds of 0.7Py and 0.95Py to assess head part slip can acquire the same identified results those are qualified or not. The slip results for the various head parts indicated that the slip of welded head by friction was very limit. The slips of head part with the other heads from small to large in sequence were threaded head and grouted sleeve head. For the threaded heads of the headed reinforcements, all the slips were smaller than 0.2 mm. For the grouted sleeve heads of them, the slips of head part without a restraining-slip nut were more significant than 0.3 mm, but the slips of head part with a restraining-slip nut enable to be reduced under 0.3 mm as long as using proper fabricated process. Test results also presented that the maximum tensile strengths of each specimen exceeded its minimum specified ultimate strength and 1.25 times its minimum specified yield strength. The testing device developed in this study can install measure instruments quick and visually and get reliable measure results of head part slip. It also significantly reduces 78% of testing time per piece compared with the existed testing fixture. The load capacity of the fixture is for #12 reinforcement of SD 690.

並列關鍵字

headed reinforcement ； testing device to test single headed reinforcement in tension ； slip of head part ； elongation ； tensile strength

參考文獻

ACI Committee 318 (2008, 2019), Building Code Requirements for Structural Concrete and Commentary, American Concrete Institute (ACI), Farmington Hills, Mich.

ASTM (2018a), “Standard Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement,” (ASTM A706/A706M-18), ASTM International, West Conshohocken, Pennsylvania, 7 pp.

ASTM (2018b), “Standard Specification for Headed Steel Bars for Concrete Reinforcement,” (ASTM A970/A970M-18), ASTM International, West Conshohocken, Pennsylvania, 10 pp.

ASTM (2019), “Standard Test Methods and Definitions for Mechanical Testing of Steel Products1,” (ASTM A370-19), ASTM International, West Conshohocken, Pennsylvania.

ASTM (2020), “Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement,” (ASTM A615/A615M-20), ASTM International, West Conshohocken, Pennsylvania, 7 pp.