鋁合金管內填充混凝土之軸壓行為

Abstract

鋁合金具有抗腐蝕性、表面處理性佳及延展性佳之特性，本研究以實驗探討鋁合金管填充混凝土短柱之軸壓行為。本研究進行34組小尺寸鋁合金管填充混凝土短柱軸向加載試驗，以探討試體參數對於極限強度與行為之影響。試體設計參數為斷面形狀(圓管與方管)、鋁合金管寬厚比(6.72至33.31)及混凝土強度(普通強度與高強度混凝土)。試驗結果顯示，由試體之載重位移曲線可見鋁合金管對內灌之混凝土可提供良好之圍束效果，試體達極限強度後載重位移曲線下降趨勢普遍皆十分平緩，尤其是圓管試體。圓管試體之實驗強度較標稱強度高出許多，而方管試體之實驗強度較接近標稱值。試體之鋁合金管寬厚比值愈小時，鋁合金管提供之圍束及整體軸向極限應變愈大。採用鋁合金與混凝土軸壓強度疊加之計算極限強度，顯示若混凝土軸壓強度未能有效考慮圍束效應，則圓管試體極限強度普遍大於計算強度，方管試體極限強度則較為接近計算強度。

Aluminum alloy is characterized by properties of good corrosion resistance, surface treatment, and ductility. This research was conducted experimentally to investigate the behavior of axially loaded concrete-filled aluminum alloy tubes (CFAAT). Thirty-four small-scale CFAAT specimens were tested to study the effect of specimen parameters on the axially loaded ultimate strength and behavior. The design parameters for the specimens were the shape of the cross-section (circular and square tube), width-thickness ratio of the aluminum alloy tube (6.72 to 33.31), and concrete strength (normal strength and high strength concrete). The test results indicate that, as demonstrated in the load-displacement curves, the aluminum tube can provide confinement for the concrete-filled inside the tube, and the branch of the curves beyond the ultimate strength was moderately descended, especially for circular specimens. The test ultimate strengths of the circular specimens were much high than their nominal strengths, while those of the square specimens were close to the nominal strengths. For those specimens with small width-thickness ratio, the confinement provided by the aluminum alloy tube and axial ultimate strain became large. Ultimate strengths calculated by superposition of the axial strengths of the aluminum alloy tube and the concrete indicate that the test strengths of the circular specimens were generally greater than those calculated when the calculated concrete strength did not take into account the confinement effect. However, the test strengths of the square specimens were close to the calculated strength.