金(jin)匱(kui)大(da)橋(qiao)(qiao)(qiao),簡稱金(jin)匱(kui)橋(qiao)(qiao)(qiao)。現(xian)有金(jin)匱(kui)橋(qiao)(qiao)(qiao)位于(yu)無錫市(shi)中心(xin)城區南長區,為(wei)城市(shi)主(zhu)干(gan)道(dao)(dao)太湖(hu)大(da)道(dao)(dao)跨越(yue)京杭運(yun)河(he)的一座橋(qiao)(qiao)(qiao)梁。原金(jin)匱(kui)橋(qiao)(qiao)(qiao)為(wei)鋼(gang)筋混(hun)凝(ning)土剛(gang)架拱橋(qiao)(qiao)(qiao),由于(yu)拱趾沉(chen)降不均勻,現(xian)已限載通行(xing)。根據城市(shi)規劃,擬(ni)在舊橋(qiao)(qiao)(qiao)原址上重(zhong)建(jian)本項目。改建(jian)后(hou)金(jin)匱(kui)橋(qiao)(qiao)(qiao)采用55m+105m+55m鋼(gang)桁(heng)架鋼(gang)箱梁橋(qiao)(qiao)(qiao),橋(qiao)(qiao)(qiao)寬46m,主(zhu)跨跨越(yue)京杭大(da)運(yun)河(he),邊跨跨越(yue)運(yun)河(he)東路和運(yun)河(he)西路。
金(jin)匱橋地處太湖廣(guang)場,景(jing)觀要求(qiu)(qiu)高,因(yin)此需(xu)要大橋具有(you)較(jiao)強(qiang)的(de)標志(zhi)性。大橋橋面較(jiao)寬,既(ji)要滿足通航(hang)及運河(he)東路凈空要求(qiu)(qiu),又(you)需(xu)盡早落(luo)地進(jin)入兩(liang)端(duan)連接的(de)隧道,故梁體高度(du)應盡可能小。
在(zai)比(bi)選了各種橋型方案后(hou),對(dui)于主跨為(wei)100m左右,橋寬46m的橋梁,采用(yong)下(xia)承式鋼桁梁可謂(wei)最(zui)佳(jia)選擇(ze)。設計中創新地(di)將(jiang)懸索橋造(zao)型與(yu)傳(chuan)統(tong)鋼桁梁有機地(di)結合,利(li)用(yong)主桁富于變化的曲線,塑造(zao)出(chu)風格獨(du)特的鋼桁梁橋。
主梁(liang)采(cai)用(yong)開(kai)口式主桁(heng)(heng)(heng)(heng)與(yu)鋼(gang)箱(xiang)梁(liang)相結(jie)合,此類結(jie)構在(zai)國(guo)內應用(yong)較少。開(kai)口式主桁(heng)(heng)(heng)(heng)由于沒有(you)橫聯(lian)與(yu)平聯(lian),橋面(mian)(mian)視線(xian)更開(kai)闊,景(jing)觀效果更好。但在(zai)汽車(che)活載作用(yong)下,主桁(heng)(heng)(heng)(heng)上弦跨(kua)中桿件受壓,容(rong)易發生整體(ti)失穩,對于跨(kua)度不(bu)大、桁(heng)(heng)(heng)(heng)高(gao)不(bu)高(gao)的(de)鋼(gang)桁(heng)(heng)(heng)(heng)梁(liang),通(tong)過控制主桁(heng)(heng)(heng)(heng)上弦跨(kua)中桿件應力水平,能(neng)有(you)效地解決主桁(heng)(heng)(heng)(heng)的(de)整體(ti)失穩問題。對主桁(heng)(heng)(heng)(heng)桁(heng)(heng)(heng)(heng)數的(de)選擇,可(ke)采(cai)用(yong)3片主桁(heng)(heng)(heng)(heng),橋面(mian)(mian)系采(cai)用(yong)縱、橫肋加固的(de)正交異性鋼(gang)橋板(ban)面(mian)(mian)體(ti)系;也(ye)可(ke)采(cai)用(yong)2片主桁(heng)(heng)(heng)(heng),橋面(mian)(mian)系采(cai)用(yong)正交異性板(ban)鋼(gang)箱(xiang)梁(liang)體(ti)系,這兩種均能(neng)滿足通(tong)航(hang)凈空要求。經多(duo)方面(mian)(mian)比(bi)較,采(cai)用(yong)2片主桁(heng)(heng)(heng)(heng)、橋面(mian)(mian)系為正交異性板(ban)鋼(gang)箱(xiang)梁(liang)體(ti)系。