鋼結構的特點有哪些
1、材料強度高,自身重量輕。鋼材強(qiang)度(du)(du)較高,彈性(xing)模(mo)量(liang)也(ye)高。與混凝(ning)土和木材相比,其密度(du)(du)與屈服(fu)強(qiang)度(du)(du)的(de)(de)比值相對(dui)較低,因而(er)在同(tong)樣受力條件下鋼(gang)結構的(de)(de)構件截面小,自重輕(qing),便于運輸和安裝,適于跨度(du)(du)大,高度(du)(du)高,承載重的(de)(de)結構。
2、鋼(gang)材韌性(xing),塑性(xing)好(hao),材質均(jun)勻,結構(gou)可靠性(xing)高(gao)。適于承(cheng)受沖(chong)擊和動(dong)力荷載(zai),具有良好(hao)的抗震性(xing)能(neng)。鋼(gang)材內部組織(zhi)結構(gou)均(jun)勻,近(jin)于各向同性(xing)勻質體。鋼(gang)結構(gou)的實際工(gong)作性(xing)能(neng)比(bi)較符(fu)合計算理論。所以鋼(gang)結構(gou)可靠性(xing)高(gao)。
3、鋼結(jie)(jie)構制造安裝(zhuang)機械(xie)化程(cheng)度高(gao)。鋼結(jie)(jie)構構件(jian)便于在工(gong)廠(chang)制造、工(gong)地拼裝(zhuang)。工(gong)廠(chang)機械(xie)化制造鋼結(jie)(jie)構構件(jian)成品精(jing)度高(gao)、生產效率高(gao)、工(gong)地拼裝(zhuang)速度快、工(gong)期短(duan)。鋼結(jie)(jie)構是工(gong)業化程(cheng)度最(zui)高(gao)的(de)一種結(jie)(jie)構。
4、鋼結(jie)構密(mi)(mi)封性(xing)(xing)能好,由于焊接結(jie)構可(ke)以(yi)做到完全密(mi)(mi)封,可(ke)以(yi)作(zuo)成氣密(mi)(mi)性(xing)(xing),水(shui)密(mi)(mi)性(xing)(xing)均很(hen)好的(de)高壓(ya)(ya)容(rong)器(qi),大型油池,壓(ya)(ya)力管道等。
5、鋼結構耐熱(re)不耐火,當溫度(du)(du)(du)在(zai)150℃以(yi)下時,鋼材(cai)(cai)性(xing)質變化很小。因而鋼結構適用于(yu)熱(re)車間(jian),但結構表面受150℃左右的(de)熱(re)輻射時,要(yao)采(cai)用隔熱(re)板加以(yi)保(bao)護(hu)。溫度(du)(du)(du)在(zai)300℃-400℃時.鋼材(cai)(cai)強度(du)(du)(du)和彈(dan)性(xing)模量均顯著(zhu)下降,溫度(du)(du)(du)在(zai)600℃左右時,鋼材(cai)(cai)的(de)強度(du)(du)(du)趨(qu)于(yu)零(ling)。在(zai)有特殊(shu)防火需求的(de)建(jian)筑中,鋼結構必須(xu)采(cai)用耐火材(cai)(cai)料(liao)加以(yi)保(bao)護(hu)以(yi)提高耐火等級。
6、鋼結(jie)構耐(nai)腐(fu)(fu)蝕(shi)性(xing)差,特別是(shi)在(zai)潮濕和腐(fu)(fu)蝕(shi)性(xing)介質的環境中(zhong),容易銹蝕(shi)。一般鋼結(jie)構要除(chu)銹、鍍鋅(xin)或涂料,且(qie)要定期維(wei)護(hu)。對處(chu)于海水(shui)中(zhong)的海洋平臺結(jie)構,需采用“鋅(xin)塊(kuai)陽極保護(hu)”等特殊措施(shi)予(yu)以防(fang)腐(fu)(fu)蝕(shi)。
7、低碳、節能、綠色環保,可重復利用。鋼結構建(jian)筑拆(chai)除幾乎不(bu)會產生建(jian)筑垃圾,鋼材可以(yi)回收再利用。
鋼結構的材料要求
1、強度
鋼材的(de)(de)強(qiang)度指標由彈性極限(xian)σe,屈服(fu)極限(xian)σy,和抗(kang)拉極限(xian)σu,設計時以(yi)鋼材的(de)(de)屈服(fu)強(qiang)度為基礎(chu),屈服(fu)強(qiang)度高可以(yi)減輕結構的(de)(de)自重,節省鋼材,降(jiang)低造價。抗(kang)拉強(qiang)度σu即(ji)是鋼材破壞前所能承受的(de)(de)最大(da)應力,此時的(de)(de)結構因塑性變形很(hen)大(da)而失去使用性能,但結構變形大(da)而不垮,應能夠滿足(zu)結構抵抗(kang)罕遇地震(zhen)的(de)(de)要求(qiu)。
2、塑性
鋼材的塑性(xing)一般指應力超過(guo)屈服點后,具有顯著的塑性(xing)變形(xing)而不斷裂(lie)的性(xing)質。衡(heng)量鋼材塑性(xing)變形(xing)能力的主(zhu)要(yao)指標是(shi)伸長(chang)率(lv)(lv)δ和斷面收縮率(lv)(lv)ψ。
3、冷彎性能
鋼材(cai)(cai)的冷(leng)(leng)彎性(xing)能(neng)(neng)是衡(heng)量(liang)鋼材(cai)(cai)在常溫(wen)下彎曲加工產生塑性(xing)變形(xing)時對產生裂紋(wen)的抵抗能(neng)(neng)力。鋼材(cai)(cai)的冷(leng)(leng)彎性(xing)能(neng)(neng)是用冷(leng)(leng)彎實驗(yan)來檢驗(yan)鋼材(cai)(cai)承受規(gui)定(ding)彎曲程(cheng)度的彎曲變形(xing)性(xing)能(neng)(neng)。
4、沖擊韌性
鋼材(cai)的(de)沖擊(ji)(ji)韌性(xing)是指(zhi)(zhi)鋼材(cai)在沖擊(ji)(ji)荷載作用(yong)下,斷(duan)(duan)裂過程中(zhong)(zhong)吸收(shou)機械動能的(de)一(yi)種能力,是衡量鋼材(cai)抵(di)抗(kang)沖擊(ji)(ji)荷裁作用(yong),可能因低溫、應(ying)力集中(zhong)(zhong),而(er)導致(zhi)脆性(xing)斷(duan)(duan)裂的(de)一(yi)項機械性(xing)能。一(yi)般通過標(biao)準試件的(de)沖擊(ji)(ji)試驗來獲(huo)得鋼材(cai)的(de)沖擊(ji)(ji)韌性(xing)指(zhi)(zhi)標(biao)。
5、焊接性能
鋼(gang)(gang)材(cai)(cai)的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)是(shi)指(zhi)在—定的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)工藝條(tiao)件下,獲得性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)良好的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)接(jie)(jie)頭。焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)可(ke)分為焊(han)(han)(han)(han)(han)接(jie)(jie)過程中(zhong)的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)和使用(yong)(yong)(yong)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)上的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)兩種。焊(han)(han)(han)(han)(han)接(jie)(jie)過程中(zhong)的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)是(shi)指(zhi)焊(han)(han)(han)(han)(han)接(jie)(jie)過程中(zhong)焊(han)(han)(han)(han)(han)縫及焊(han)(han)(han)(han)(han)縫附近金屬不(bu)產生(sheng)熱(re)裂紋或冷(leng)卻(que)不(bu)產生(sheng)冷(leng)卻(que)收縮裂紋的(de)敏(min)感性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)。焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)好,是(shi)指(zhi)在一定焊(han)(han)(han)(han)(han)接(jie)(jie)工藝條(tiao)件下,焊(han)(han)(han)(han)(han)縫金屬和附近母材(cai)(cai)均不(bu)產生(sheng)裂紋。使用(yong)(yong)(yong)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)上的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)是(shi)指(zhi)焊(han)(han)(han)(han)(han)縫處(chu)的(de)沖擊韌性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)和熱(re)影(ying)響區(qu)內(nei)延性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng),要求焊(han)(han)(han)(han)(han)縫及熱(re)影(ying)響區(qu)內(nei)鋼(gang)(gang)材(cai)(cai)的(de)力學(xue)(xue)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)不(bu)低于母材(cai)(cai)的(de)力學(xue)(xue)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)。我(wo)國采用(yong)(yong)(yong)焊(han)(han)(han)(han)(han)接(jie)(jie)過程的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)試驗方(fang)法(fa),也(ye)采用(yong)(yong)(yong)使用(yong)(yong)(yong)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)使用(yong)(yong)(yong)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)質(zhi)上的(de)焊(han)(han)(han)(han)(han)接(jie)(jie)性(xing)(xing)(xing)(xing)(xing)(xing)(xing)(xing)能(neng)(neng)(neng)試驗方(fang)法(fa)。
6、耐久性
影響鋼材耐(nai)久(jiu)性的(de)(de)因素很(hen)多(duo)。首(shou)先是鋼(gang)(gang)材(cai)(cai)的(de)(de)耐(nai)腐(fu)蝕性差,必須采(cai)取防(fang)(fang)(fang)護(hu)措(cuo)(cuo)施(shi),防(fang)(fang)(fang)止鋼(gang)(gang)材(cai)(cai)腐(fu)蝕生銹。防(fang)(fang)(fang)護(hu)措(cuo)(cuo)施(shi)有(you):定(ding)期對(dui)鋼(gang)(gang)材(cai)(cai)油漆(qi)維護(hu),采(cai)用(yong)鍍(du)鋅鋼(gang)(gang)材(cai)(cai),在(zai)有(you)酸(suan),堿(jian),鹽等強腐(fu)蝕介質(zhi)條件下(xia),采(cai)用(yong)特殊防(fang)(fang)(fang)護(hu)措(cuo)(cuo)施(shi),如海洋平臺結構采(cai)用(yong)“陽極保護(hu)”措(cuo)(cuo)施(shi)防(fang)(fang)(fang)止導管架(jia)(jia)腐(fu)蝕,在(zai)導管架(jia)(jia)上固定(ding)上鋅錠(ding),海水電解質(zhi)會自動(dong)先腐(fu)蝕鋅錠(ding),從而達到(dao)保護(hu)鋼(gang)(gang)導管架(jia)(jia)的(de)(de)功能。其次由于鋼(gang)(gang)材(cai)(cai)在(zai)高溫和長期荷載作用(yong)下(xia),其破壞強度(du)比短期強度(du)降低(di)較多(duo),故對(dui)長期高溫作用(yong)下(xia)的(de)(de)鋼(gang)(gang)材(cai)(cai),要(yao)測(ce)定(ding)持久(jiu)強度(du)。鋼(gang)(gang)材(cai)(cai)隨(sui)時(shi)間推移會自動(dong)變(bian)硬(ying)、變(bian)脆(cui)、即“時(shi)效”現象。對(dui)低(di)溫荷載作用(yong)下(xia)的(de)(de)鋼(gang)(gang)材(cai)(cai)要(yao)檢驗其沖(chong)擊韌性。