钢管-UCA短柱轴压承载力试验研究

Experimental Study on Axial Compressive Bearing Capacity of Steel Pipe -UCA Short Column

摘要:

为研究钢管-UCA短柱轴压性能，设计UCA-4、UCA-6、UCA-8和C70-6四组试件，分析混凝土类别、钢管壁厚以及强度对破坏模式、荷载-位移曲线和套箍效应的影响，并基于试验结果，对多种轴压承载力计算公式进行评估。结果表明，UCA-4与UCA-6试件套箍系数较低呈剪切型破坏，UCA-8与C70-6试件套箍系数较高为腰鼓形破坏。提高钢管强度和壁厚能提高试件极限承载力和套箍效应，而增强混凝土强度仅能提升试件极限承载力，对套箍效应无明显增强。评估承载力时，按照《钢管混凝土结构技术规程》（DBJ/T 13-51—2020）计算误差均在10%以内，具有良好的准确性和工程适用性。依据某上承式钢筋混凝土拱桥主拱圈尺寸，在轴压承载力相近条件下，内填UCA材料相较于C70可减少钢材用量12%，缩减混凝土体积23%。

Abstract:

In order to study the axial compression performance of steel pipe-UCA short columns, four groups of specimens (UCA-4, UCA-6, UCA-8 and C70-6) are designed to analyze the effects of concrete type, steel pipe wall thickness and strength on failure mode, load-displacement curve and hoop effect. Based on the results, a variety of axial compression bearing capacity calculation formulas are evaluated. The results show that the low hoop coefficient of UCA-4 and UCA-6 specimens presents shear-shaped failure, and the high hoop coefficient of UCA-8 and C70-6 specimens is waist-drum-shaped failure. The increase of strength and wall thickness of steel pipe can improve the ultimate bearing capacity and hoop effect of the specimen, and the increase of concrete strength can only improve the ultimate bearing capacity of the specimen with no significant enhancement to the hoop effect. During the evaluation of bearing capacity, the calculation errors are all within 10% according to the Technical Code for Concrete-filled Steel Tube Structures (DBJ/T 13-51—2020), which has good accuracy and engineering applicability. Based on the dimensions of the main arch ring of a deck-type reinforced concrete arch bridge, under similar axial compressive bearing capacity conditions, the UCA material filled inside can reduce the steel usage by 12% and the concrete volume by 23% compared with C70.