某独斜塔地锚式预应力混凝土(PC)斜拉桥塔柱倾角优化分析

摘要

为了研究独塔地锚式预应力混凝土(prestressed concrete,PC)斜拉桥塔柱倾角的合理取值范围,采用非线性回归的方法,通过对某斜塔柱进行受力分析,得到最小塔柱倾角近似计算公式;推导拉索、锚碇、主梁、主塔的材料用量计算公式,并引入材料单价系数,对总造价与塔柱倾角及地锚背索倾角的关系进行分析,得到经济塔柱倾角近似计算公式.结果表明:独斜塔地锚式PC斜拉桥最小塔柱倾角随主跨边索倾角的增大而增大,随轴力作用下容许压应力绝对值的增大而减小;经济塔柱倾角受地锚背索倾角及轴力作用下容许压应力的影响,地锚背索倾角及轴力作用下容许压应力绝对值越小,经济塔柱倾角越大;地锚背索倾角在一定范围内,总造价随塔柱倾角的减小先减小后增大,减小地锚背索倾角,可降低总造价;塔柱倾角a不宜小于60°,地锚背索倾角θ不宜小于43°.%In order to study the pylon inclination's appropriate range of single inclined pylon earthanchored prestressed concrete (PC) cable-stayed bridge,an approximate formula about minimum inclination of pylon was obtained by the nonlinear regression analysis methods and stress analysis of inclined pylon.The equations for material amounts of the cables,anchor,main beam and pylon were derived.The approximate formula about economical inclination of pylon was obtained by introducing the cost of per unit weight or volume of each material and the relationship between the cost of the entire bridge and the factors (the inclination of pylon and the inclination of earth-anchored cables) was analyzed.Results show that firstly,as for single inclined pylon earth-anchored cable-stayed bridge,the minimum inclination of pylon increases when the inclination of side cables at main span increases,and decreases when the allowable compression stress absolute value under the action of axial force increases.Secondly,the economical inclination of pylon is influenced by the inclination of earth-anchored cables and the allowable compression stress under the action of axial force.The economical inclination of pylon increases when the inclination of earth-anchored cables and the allowable compression stress absolute value under the action of axial force decrease.Thirdly,when the inclination of earth-anchored cables is within a given range,the cost of the entire bridge initially decreases,but then turns to increase with the decline of inclination of pylon.Decreasing the inclination of earth-anchored cables is beneficial to reducing the cost of the entire bridge.Finally,the inclination of pylon should be greater than 60° and the inclination of earth-anchored cables should be greater than 43°.