無(wu)梁拱(gong)有哪些作用(yong)?
無梁拱,拱形(xing)屋(wu)面被(bei)廣泛用于工業廠房(fang)、倉儲庫房(fang)、無(wu)梁(liang)拱體育場(chang)館、集(ji)貿市場(chang)、車庫機庫等，它無(wu)梁(liang)無(wu)擦(ca)、空(kong)間高大(da)開闊，可以隨意分割組合，使用方便，自重(zhong)輕(qing)、剛性強、彈性好、抗震性能優(you)越等特點。
無梁拱(gong)(gong),拱(gong)(gong)形屋(wu)(wu)面(mian)還具有(you)(you)承(cheng)(cheng)壓(ya)效果，拱(gong)(gong)所(suo)承(cheng)(cheng)受的(de)荷載(zai)不同，其壓(ya)力曲線(xian)的(de)線(xian)形也不相同，一(yi)般按恒載(zai)下(xia)壓(ya)力曲線(xian)確(que)定;在活載(zai)作用(yong)下(xia)，拱(gong)(gong)內力可(ke)能產生彎矩，這(zhe)時鉸的(de)設置就會影響(xiang)拱(gong)(gong)內彎矩的(de)分布狀(zhuang)況。與剛架相仿，只有(you)(you)地(di)基良好或兩側拱(gong)(gong)肢處有(you)(you)穩定邊跨結構(gou)時才采(cai)用(yong)無鉸拱(gong)(gong)，這(zhe)種拱(gong)(gong)很(hen)少用(yong)于(yu)房屋(wu)(wu)建筑。雙鉸拱(gong)(gong)應用(yong)較多，為(wei)適應軟弱地(di)基上支(zhi)座沉降差及拱(gong)(gong)拉桿(gan)變形，最好采(cai)用(yong)靜(jing)定結構(gou)的(de)三(san)鉸拱(gong)(gong)。
拱(gong)(gong)以(yi)曲桿抗衡(heng)并(bing)傳遞外力(li)(li)(li)給支(zhi)(zhi)(zhi)座(zuo)，故鉸支(zhi)(zhi)(zhi)座(zuo)不(bu)僅承受(shou)豎(shu)向(xiang)(xiang)力(li)(li)(li)，并(bing)有相(xiang)當大的(de)(de)水(shui)(shui)平向(xiang)(xiang)外的(de)(de)拱(gong)(gong)腳推(tui)力(li)(li)(li)，其(qi)合力(li)(li)(li)就位(wei)(wei)于拱(gong)(gong)軸曲線(xian)在(zai)支(zhi)(zhi)(zhi)座(zuo)點的(de)(de)切(qie)線(xian)方向(xiang)(xiang)上。拱(gong)(gong)腳有推(tui)力(li)(li)(li)是其(qi)主要力(li)(li)(li)學特征之一，矢高f越(yue)小，推(tui)力(li)(li)(li)越(yue)大。一次超靜(jing)定的(de)(de)雙鉸拱(gong)(gong)，金屬屋面支(zhi)(zhi)(zhi)座(zuo)的(de)(de)垂直或水(shui)(shui)平位(wei)(wei)移均會引起內力(li)(li)(li)變(bian)化，對支(zhi)(zhi)(zhi)座(zuo)在(zai)推(tui)力(li)(li)(li)作(zuo)用(yong)下無變(bian)位(wei)(wei)的(de)(de)要求就更嚴(yan)格。由此可見，為了使(shi)拱(gong)(gong)保持正(zheng)常工作(zuo)，務(wu)必確保其(qi)支(zhi)(zhi)(zhi)座(zuo)能承受(shou)住推(tui)力(li)(li)(li)而(er)不(bu)位(wei)(wei)移，故拱(gong)(gong)腳推(tui)力(li)(li)(li)的(de)(de)結(jie)(jie)構處理，是拱(gong)(gong)結(jie)(jie)構設計(ji)的(de)(de)中心(xin)問(wen)題
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