混凝土偏压柱承载力计算方法

Calculation methods of bearing capacities of eccentrically loaded concrete columns

应用《公路圬工桥涵设计规范》(JTG D61—2005)中的砌体柱和素混凝土柱承载力计算方法以及《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG D62—2004)中的钢筋混凝土柱承载力计算方法,分别对3座跨径为70、160、420m的钢筋混凝土拱桥进行了主拱承载力验算。考虑长细比、偏心率、配筋率等参数,研究了钢筋混凝土柱的承载力变化规律,分析了混凝土拱等效梁柱的参数范围以及砌体柱、素混凝土柱、钢筋混凝土柱的极限承载力。分析结果表明:配筋率较小的钢筋混凝土拱等效成梁柱后,按JTG D61—2005计算的承载力大于按JTG D62—2004计算的结果。对配筋率较小而长细比、偏心率较大的钢筋混凝土柱,按钢筋混凝土柱计算的承载力反而小于砌体柱或素混凝土柱的承载力。可见,2种规范中混凝土偏压柱承载力计算方法存在不合理之处,需进一步改进。

By the application of the calculation methods of masonry columns and plain concrete columns in Codes for Design of Highway Masonry Bridges and Culverts （JTG D61-2005） and the calculation methods of reinforced concrete columns in Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts （JTG D62-2004）, the load carrying capacities of 3 reinforced concrete arch bridges with the spans of 70, 160, 420 m were calculated respectively. The change rules of the bearing capacities of reinforced concrete columns were studied considering slenderness ratio, eccentricity, reinforcement ratio, and etc. The parameter ranges of the equivalent beam-column of concrete arches and the ultimate bearing capacities of masonry columns, plain concrete columns and reinforced concrete columns were analyzed. Analysis result shows that the hearing capacities calculated by JTG D61-2005 are greater than those calculated by JTG D62-2004 when reinforced concrete arches with low reinforcement ratio are treated as equivalent beam-column. For reinforced concrete columns with low reinforcement ratios and high slenderness ratios and eccentricities, the bearing capacities calculated by the formulas of reinforced concrete columns are smaller than those calculated by the formulas of masonry columns or plain concrete columns. Thus it can be seen that there areunreasonable {actors in the calculation methods of eccentrically loaded concrete columns in two codes, which should be improved. 3 tabs, 7 figs, 25 refs.