金(jin)匱大(da)(da)橋(qiao),簡稱金(jin)匱橋(qiao)。現(xian)(xian)有金(jin)匱橋(qiao)位(wei)于無錫(xi)市中心(xin)城(cheng)區南長區,為城(cheng)市主干(gan)道太湖大(da)(da)道跨越京(jing)(jing)杭(hang)運(yun)河的一座橋(qiao)梁(liang)。原金(jin)匱橋(qiao)為鋼(gang)筋混凝土剛架(jia)拱橋(qiao),由于拱趾(zhi)沉(chen)降不均勻(yun),現(xian)(xian)已限(xian)載(zai)通行。根據城(cheng)市規劃,擬在舊橋(qiao)原址(zhi)上重建(jian)本項目。改建(jian)后金(jin)匱橋(qiao)采用55m+105m+55m鋼(gang)桁架(jia)鋼(gang)箱梁(liang)橋(qiao),橋(qiao)寬46m,主跨跨越京(jing)(jing)杭(hang)大(da)(da)運(yun)河,邊跨跨越運(yun)河東路(lu)和運(yun)河西路(lu)。
金匱(kui)橋地(di)處太(tai)湖廣場,景觀(guan)要求高,因此(ci)需要大(da)(da)橋具(ju)有較強的(de)標志性(xing)。大(da)(da)橋橋面(mian)較寬,既要滿足通航及運河東(dong)路凈空要求,又需盡早(zao)落地(di)進入(ru)兩端(duan)連接的(de)隧道(dao),故梁體高度應盡可能(neng)小。
在(zai)比選了各種橋(qiao)(qiao)型(xing)方案后,對(dui)于(yu)主(zhu)跨為100m左右,橋(qiao)(qiao)寬46m的橋(qiao)(qiao)梁(liang),采用下承式鋼(gang)桁梁(liang)可謂最佳選擇。設計中創新(xin)地將懸索橋(qiao)(qiao)造(zao)(zao)型(xing)與傳(chuan)統鋼(gang)桁梁(liang)有(you)機地結合,利(li)用主(zhu)桁富于(yu)變化(hua)的曲線,塑造(zao)(zao)出風格獨特(te)的鋼(gang)桁梁(liang)橋(qiao)(qiao)。
主(zhu)(zhu)(zhu)梁采(cai)用(yong)(yong)(yong)開口式主(zhu)(zhu)(zhu)桁(heng)與鋼(gang)(gang)箱(xiang)梁相(xiang)結合,此(ci)類結構在(zai)(zai)國內應用(yong)(yong)(yong)較(jiao)少。開口式主(zhu)(zhu)(zhu)桁(heng)由于(yu)沒有橫(heng)聯與平聯,橋(qiao)(qiao)面(mian)(mian)視(shi)線(xian)更(geng)開闊,景觀效果更(geng)好。但在(zai)(zai)汽車活載作用(yong)(yong)(yong)下,主(zhu)(zhu)(zhu)桁(heng)上弦跨(kua)中桿件受壓(ya),容易發生整(zheng)體失(shi)穩(wen),對于(yu)跨(kua)度不大、桁(heng)高(gao)(gao)不高(gao)(gao)的鋼(gang)(gang)桁(heng)梁,通過控制主(zhu)(zhu)(zhu)桁(heng)上弦跨(kua)中桿件應力水平,能有效地(di)解(jie)決主(zhu)(zhu)(zhu)桁(heng)的整(zheng)體失(shi)穩(wen)問題。對主(zhu)(zhu)(zhu)桁(heng)桁(heng)數的選(xuan)擇(ze),可采(cai)用(yong)(yong)(yong)3片(pian)主(zhu)(zhu)(zhu)桁(heng),橋(qiao)(qiao)面(mian)(mian)系采(cai)用(yong)(yong)(yong)縱、橫(heng)肋加固的正(zheng)交(jiao)異(yi)性鋼(gang)(gang)橋(qiao)(qiao)板面(mian)(mian)體系;也可采(cai)用(yong)(yong)(yong)2片(pian)主(zhu)(zhu)(zhu)桁(heng),橋(qiao)(qiao)面(mian)(mian)系采(cai)用(yong)(yong)(yong)正(zheng)交(jiao)異(yi)性板鋼(gang)(gang)箱(xiang)梁體系,這(zhe)兩種均能滿(man)足通航(hang)凈空要求。經多方面(mian)(mian)比較(jiao),采(cai)用(yong)(yong)(yong)2片(pian)主(zhu)(zhu)(zhu)桁(heng)、橋(qiao)(qiao)面(mian)(mian)系為正(zheng)交(jiao)異(yi)性板鋼(gang)(gang)箱(xiang)梁體系。