鋼橋(qiao)(qiao)桁(heng)(heng)架(jia)(jia)單元由上(shang)(shang)、下(xia)弦桿(gan)(gan)，豎桿(gan)(gan)和斜(xie)撐焊接(jie)而(er)成。上(shang)(shang)、下(xia)弦桿(gan)(gan)的(de)(de)一端(duan)為陰頭(tou)(tou)，另一端(duan)為陽(yang)頭(tou)(tou)，在陰、陽(yang)頭(tou)(tou)上(shang)(shang)都(dou)有銷子(zi)孔(kong)(kong)。兩(liang)(liang)節(jie)桁(heng)(heng)架(jia)(jia)拼接(jie)時，將一節(jie)的(de)(de)陽(yang)頭(tou)(tou)插入另一節(jie)的(de)(de)陰頭(tou)(tou)內，對準(zhun)銷子(zi)孔(kong)(kong)，插上(shang)(shang)銷子(zi)。桁(heng)(heng)架(jia)(jia)各孔(kong)(kong)的(de)(de)用(yong)(yong)(yong)途如下(xia):弦桿(gan)(gan)螺栓(shuan)孔(kong)(kong)用(yong)(yong)(yong)于(yu)拼裝雙(shuang)層或(huo)加(jia)強(qiang)(qiang)鋼橋(qiao)(qiao)時，將桁(heng)(heng)架(jia)(jia)螺栓(shuan)或(huo)弦桿(gan)(gan)螺栓(shuan)插入弦桿(gan)(gan)螺栓(shuan)孔(kong)(kong)內，使雙(shuang)層桁(heng)(heng)架(jia)(jia)或(huo)桁(heng)(heng)架(jia)(jia)與加(jia)強(qiang)(qiang)弦桿(gan)(gan)連接(jie)起來(lai)；支撐架(jia)(jia)孔(kong)(kong)用(yong)(yong)(yong)來(lai)安(an)裝支撐架(jia)(jia)，當(dang)桁(heng)(heng)架(jia)(jia)用(yong)(yong)(yong)作主(zhu)梁(liang)(liang)(liang)時，用(yong)(yong)(yong)中間兩(liang)(liang)個孔(kong)(kong)，用(yong)(yong)(yong)作橋(qiao)(qiao)腳時，用(yong)(yong)(yong)端(duan)部兩(liang)(liang)個孔(kong)(kong)，以(yi)加(jia)強(qiang)(qiang)兩(liang)(liang)排(pai)桁(heng)(heng)架(jia)(jia)間的(de)(de)聯(lian)系(xi)；風構孔(kong)(kong)用(yong)(yong)(yong)于(yu)連接(jie)抗(kang)風拉桿(gan)(gan)；端(duan)豎桿(gan)(gan)上(shang)(shang)的(de)(de)支撐架(jia)(jia)孔(kong)(kong)，用(yong)(yong)(yong)于(yu)安(an)裝支撐架(jia)(jia)、斜(xie)撐和聯(lian)板；橫梁(liang)(liang)(liang)夾(jia)具孔(kong)(kong)用(yong)(yong)(yong)于(yu)安(an)裝橫梁(liang)(liang)(liang)夾(jia)具。下(xia)弦桿(gan)(gan)上(shang)(shang)設(she)有4塊橫梁(liang)(liang)(liang)墊(dian)(dian)板，墊(dian)(dian)板上(shang)(shang)有栓(shuan)釘，用(yong)(yong)(yong)于(yu)限定橫梁(liang)(liang)(liang)的(de)(de)位置。