預力混凝土梁扭力實驗研究與3D雷射掃描應用

Torsional Experiment of Prestressed Concrete Beams with Application of 3D Laser Scanning

任家紹(Chia-Shao Jen)

指導教授 ： 鄭全桓

國立暨南國際大學/科技學院/土木工程學系/碩士(2016年)

摘要

本研究延續前期研究實心預力混凝土(Prestressed Concrete, 簡稱PC)梁扭力實驗，將試驗推展至中空PC梁扭力實驗，設計製作兩組不同斷面尺寸、混凝土強度、壁厚比及預力比之中空PC梁試體，進行純扭力試驗，討論比較試驗結果。
本試驗製作之中空PC梁試體可分為三部分：固定端之RC block、測試區主梁以及轉動端之十字型RC橫梁，並於試驗前在預埋的預力套管內安裝鋼絞線和端錨等裝置，再使用後拉法施加預力。在測試區主梁內亦放置適當大小的保麗龍以模擬中空斷面達成設計之壁厚比。本研究之試驗方式能將力量傳遞至測試區主梁，使測試區主梁只受到純扭力作用。
本實驗測定之數值包含：扭矩、扭轉角、剪力流有效厚度 、鋼筋和混凝土表面應變、預力鋼腱拉力及試體縱向伸長等，並將實驗結果與受扭實心與中空RC桿件之開裂前(pre-cracking)統一解析公式進行比較。此外，本研究也應用3D雷射掃描的點雲資料，量測試體的扭轉角，並與上述之扭轉角比較，探討3D雷射掃描應用於混凝土梁扭力實驗的適用性。
實驗結果顯示，使用RC梁開裂前解析公式分析六組PC梁試體，計算的開裂扭矩值 小於PC梁試體的開裂扭矩 實驗值，且四個實心試體的開裂扭矩 實驗值與使用RC梁開裂前解析公式的開裂扭矩 實驗值之比值與預力比呈現相當規律的趨勢，顯示預力愈大，PC梁 值大於對應RC梁 的差值也愈大。此外，使用3D雷射掃描量測的單位扭轉角與原量測方式的結果大致符合。

關鍵字

鋼筋混凝土 ； 扭力梁扭矩 ； 扭轉角 ； 預力混凝土梁 ； 預力 ； 3D雷射掃描

並列摘要

As a succeeding part of the previous research of solid prestressed concrete (PC) beams, this study extended the torsional experiment to hollow PC beams. by conducting test on two hollow PC beam specimens subjected to pure torsion. This thesis describes the experimental project and presents the experimental results.
Each of the hollow PC beam specimens consists of three parts, namely, the RC block at the fixed end, the middle longitudinal test beam, and the cruciform transverse beams at the twist end. The anchorage devices and longitudinal prestressing duct were embedded in the concrete of each specimen. After the specimen had been cast and reached its concrete strength, the longitudinal prestressing forces were applied by tensioning the individual strands one by one. Styrofoam was placed in the test zone longitudinal test beam to produce the hollow cross section.
Eight quantities were experimentally determined for each specimen using continuous measurement and automatic data reading and recording: (1) torque, (2) twist angle, (3) thickness of shear flow zone, (4) strain of nonprestressing reinforcing steel bar, (5) diagonal compressive strain at the concrete surface, (6) diagonal tensile strain at the concrete surface, (7) longitudinal prestressing force, and (8) longitudinal elongation of test beam. The experimental results are compared with a rational formula for pre-cracking torque-twist responses for reinforced concrete (RC) members. This study also explored the feasibility of applying 3D laser scanning techniques in the torsion experiments. The twist angles obtained using 3D laser scanning were compared.
The results of this study showed that the experimental cracking torques of the PC beam specimens is larger than the values calculated by the rational formula for RC members. The ratios of the experimental cracking torques (PC) to the calculated cracking torques were compared with the prestress ratios, showing a regular tendency. The twist angles obtained using 3D laser scanning agree well with the experimental twist angle values obtained from the original measurement method.

並列關鍵字

Reinforced concrete ； torsion ； beam ； torque ； twist ； prestressed concrete ； prestressing force ； 3D laser scanning

參考文獻

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