鋼橋(qiao)桁(heng)(heng)架(jia)(jia)(jia)(jia)單元由上(shang)(shang)、下弦(xian)(xian)桿(gan)(gan)(gan)，豎桿(gan)(gan)(gan)和斜撐焊接(jie)而成。上(shang)(shang)、下弦(xian)(xian)桿(gan)(gan)(gan)的一(yi)(yi)端(duan)(duan)為陰(yin)頭，另(ling)一(yi)(yi)端(duan)(duan)為陽頭，在陰(yin)、陽頭上(shang)(shang)都有(you)銷(xiao)子(zi)(zi)孔。兩(liang)節桁(heng)(heng)架(jia)(jia)(jia)(jia)拼接(jie)時，將(jiang)一(yi)(yi)節的陽頭插入另(ling)一(yi)(yi)節的陰(yin)頭內(nei)，對準銷(xiao)子(zi)(zi)孔，插上(shang)(shang)銷(xiao)子(zi)(zi)。桁(heng)(heng)架(jia)(jia)(jia)(jia)各孔的用(yong)(yong)(yong)(yong)途如下:弦(xian)(xian)桿(gan)(gan)(gan)螺(luo)栓孔用(yong)(yong)(yong)(yong)于拼裝(zhuang)雙(shuang)層或(huo)加(jia)強鋼橋(qiao)時，將(jiang)桁(heng)(heng)架(jia)(jia)(jia)(jia)螺(luo)栓或(huo)弦(xian)(xian)桿(gan)(gan)(gan)螺(luo)栓插入弦(xian)(xian)桿(gan)(gan)(gan)螺(luo)栓孔內(nei)，使雙(shuang)層桁(heng)(heng)架(jia)(jia)(jia)(jia)或(huo)桁(heng)(heng)架(jia)(jia)(jia)(jia)與加(jia)強弦(xian)(xian)桿(gan)(gan)(gan)連接(jie)起來(lai)；支(zhi)(zhi)撐架(jia)(jia)(jia)(jia)孔用(yong)(yong)(yong)(yong)來(lai)安裝(zhuang)支(zhi)(zhi)撐架(jia)(jia)(jia)(jia)，當桁(heng)(heng)架(jia)(jia)(jia)(jia)用(yong)(yong)(yong)(yong)作主(zhu)梁時，用(yong)(yong)(yong)(yong)中間兩(liang)個孔，用(yong)(yong)(yong)(yong)作橋(qiao)腳時，用(yong)(yong)(yong)(yong)端(duan)(duan)部兩(liang)個孔，以加(jia)強兩(liang)排桁(heng)(heng)架(jia)(jia)(jia)(jia)間的聯系(xi)；風構孔用(yong)(yong)(yong)(yong)于連接(jie)抗風拉(la)桿(gan)(gan)(gan)；端(duan)(duan)豎桿(gan)(gan)(gan)上(shang)(shang)的支(zhi)(zhi)撐架(jia)(jia)(jia)(jia)孔，用(yong)(yong)(yong)(yong)于安裝(zhuang)支(zhi)(zhi)撐架(jia)(jia)(jia)(jia)、斜撐和聯板；橫梁夾具孔用(yong)(yong)(yong)(yong)于安裝(zhuang)橫梁夾具。