review(鋼結(jié)構(gòu)基本原理復(fù)習(xí)).ppt

1、1,鋼結(jié)構(gòu)基本原理復(fù)習(xí),Design Principles of Steel Structure,Design Principles of Steel Structure,1 Summarize,Key 1: What are the features of steel structure?,(1) High strength of steel, light weight of structure（鋼材強(qiáng)度高，結(jié)構(gòu)質(zhì)量輕） (2) Isotropic material, high reliability（材質(zhì)均勻，可靠度高） (3) Convenient fabrication, quick

2、erection（制作方便，施工快速） (4) Good leakproofness（密閉性好） (5) Heat-resistant but not refractory（耐熱不耐火） (6) Be corroded easily , maintained costly（易腐蝕，維修費(fèi)用大）,The structural limit state,Key 2: The Design Method of Steel Structure,a. The ultimate limit states: The basic combination of load effects shall be cons

3、idered and, if necessary, the accidental combination of load effects shall also be considered. b. The serviceability limit state: The load standard combination of steel structure design is only considered.,Design Principles of Steel Structure,1 Summarize,(1) Higher fy and fu（有較高的fy 和 fu）,(2) Good Pl

4、asticity and impact toughness（有良好的塑性和沖擊韌性）,(3) Good machinability（有良好的加工性能）,(4) Good adaptability to working circumstance（對環(huán)境良好的適應(yīng)能力）,Design Principles of Steel Structure,2 steel material,Key 1: The requirements of steel structure material,Key 2: Failure modes of steel structure material,(1) Plastic

5、 failure (塑性破壞) There is obvious deformation or collapse omen before failure. (2) Brittle failure (脆性破壞) There is little deformation or no warning before failure. (3) 影響脆性破壞的因素化學(xué)成分、冶金質(zhì)量、溫度（低溫）、冷作硬化、時(shí)效、應(yīng)力集中、復(fù)雜應(yīng)力。,Design Principles of Steel Structure,2 steel material,Design Principles of Steel Structu

6、re,2 steel material,Key 3: The main mechanical properties of steel,(1) Strength fu, fy fu, fy , f (2) Plasticity 材料發(fā)生塑性變形而不斷裂的性質(zhì) (3) Cold bending performance鋼材發(fā)生塑變時(shí)對產(chǎn)生裂紋的抵抗能力，是判別鋼材塑性及冶金質(zhì)量的綜合指標(biāo)。 (4) Impact toughness動(dòng)力指標(biāo)，鋼材在斷裂或塑變時(shí)吸收能量的能力，是強(qiáng)度與塑性的綜合表現(xiàn)。 (5) Weldability (6) Durability,注：承重結(jié)構(gòu)的鋼材至少應(yīng)保證fu, fy

7、 , d三項(xiàng)指標(biāo)滿足要求。,Key 4: Factors affecting the performance of steel,(1) The influence of chemical composition(化學(xué)成分) C, Mn, Si, S (hot shortness), P (Cold shortness). (2) The influence of steel-making (鋼材生產(chǎn)過程) (3) Temperature influence (溫度) High and low Temperature (4) Hardening influence (硬化) f, d , Akv

8、 (5) The influence of stress concentration (應(yīng)力集中),Design Principles of Steel Structure,2 steel material,Key 5: Fatigue of steel structure,Design Principles of Steel Structure,2 steel material,(1) 疲勞破壞的特征： 脆性破壞 (2) 影響因素： 構(gòu)件和連接的構(gòu)造類型 循環(huán)次數(shù) 循環(huán)應(yīng)力比 應(yīng)力幅 殘余應(yīng)力,Key 6: Types of steel,(1) 碳素結(jié)構(gòu)鋼：代表Q235 (2) 低合金高強(qiáng)度

9、鋼：代表Q345、Q390和Q420 (3) 鋼材的牌號(hào)：例如：Q235A、Q235B和Q235C 有何區(qū)別 (4) 型鋼(profiled steel): I-, H-, L-, T-, -shape.,Design Principles of Steel Structure,2 steel material,Key 1: The main types of connections,(1) welded connections (焊縫連接) 手工電弧焊、焊條與鋼材適應(yīng) (2) bolt connections (螺栓連接) Common Bolts (refined bolts and cr

10、ude bolt) High-strength Bolts (friction-type and pressure-type) (3) rivet connections (鉚釘連接),Design Principles of Steel Structure,3 Connections,Key 2: Types of Welds,(1) Groove welds (對接焊縫) 坡口形式；引、落弧板；變厚度與變寬度的連接 標(biāo)注方法： (2) Fillet welds (角焊縫) 標(biāo)注方法： (3) Strength and quality inspection of welding line（焊

11、縫質(zhì)量檢驗(yàn)與焊縫強(qiáng)度）,Design Principles of Steel Structure,3 Connections,Key 3: Details of fillet welding line,Design Principles of Steel Structure,3 Connections,板件hft,t6mm 邊緣hft-(12)mm,t6mm,hf1.2t1(鋼管構(gòu)件除外),t1為較薄焊件厚度，t為板邊角焊縫的板件厚度,；當(dāng)t24，hf =t2,t2為較厚焊件。自動(dòng)焊可減1mm；單面T形焊應(yīng)加1mm,若超出限值，則超出部分在計(jì)算中不考慮。內(nèi)力沿側(cè)縫全長均勻分布者不限,t1為較薄

12、焊件厚度， lw為每條側(cè)面焊縫的長度， b為兩條側(cè)面焊縫之間的距離,b16t1 ,當(dāng)t112mm b190mm,t112mm,t1為較薄焊件厚度,1、軸心力作用下,Key 4: Calculations of Fillet welds,Design Principles of Steel Structure,3 Connections,受力分析：,校核:,1、軸心力作用下,例題詳見作業(yè)。,Key 4: Calculations of Fillet welds,Design Principles of Steel Structure,3 Connections,2、N、M、V共同作用,Key 4

13、: Calculations of Fillet welds,Design Principles of Steel Structure,3 Connections,(1) 焊接應(yīng)力產(chǎn)生原因：不均勻加熱與冷卻 (2) 焊接殘余應(yīng)力的類型： (3) 對結(jié)構(gòu)性能的影響： 靜力強(qiáng)度：無影響 結(jié)構(gòu)剛度：降低 穩(wěn)定承載力：降低 低溫工作：變脆 疲勞強(qiáng)度：降低 (4) 減小焊接殘余應(yīng)力、變形的設(shè)計(jì)和工藝措施:,Key 5: The stress and deformation of welds,Design Principles of Steel Structure,3 Connections,(1)螺栓排

14、列：并列、錯(cuò)列 (2)螺栓排列：需要考慮受力、構(gòu)造和施工要求 (3)端距要求：不應(yīng)小于2d0 (4)中距要求：最小中距3d0 (5)排列要求：參見規(guī)范,Key 6: Details of bolts connecting,Design Principles of Steel Structure,3 Connections,（1）螺栓桿被剪斷 （2）孔壁的擠壓破壞 （3）板件被拉斷 以上破壞形式予以計(jì)算解決,Key 7: Strength failure of the shear bolt,Design Principles of Steel Structure,3 Connections,（4

15、）板件端部被剪斷（拉豁),（5）栓桿彎曲破壞,Key 7: Strength failure of the shear bolt,Design Principles of Steel Structure,3 Connections,普通螺栓群軸心力作用下抗剪計(jì)算,N1F,Key 8: Uniform shear of bolts group,Design Principles of Steel Structure,3 Connections,普通螺栓群軸心力作用下抗剪計(jì)算,Key 8: Uniform shear of bolts group,Design Principles of Stee

16、l Structure,3 Connections,Key 9: The working performance of bolt,Design Principles of Steel Structure,3 Connections,(1) 普通受剪螺栓： 從受力直至破壞經(jīng)歷四個(gè)階段，由于它允許接觸面滑動(dòng)，以螺桿剪斷或孔壁受壓破壞的極限狀態(tài)作為設(shè)計(jì)準(zhǔn)則 (2) 普通受拉螺栓：以螺栓被拉斷作為承載力極限狀態(tài) (3) 高強(qiáng)度螺栓： 高強(qiáng)度螺栓在擰緊時(shí)，螺桿中產(chǎn)生了很大的預(yù)拉力，而被連接板件間則產(chǎn)生很大的預(yù)壓力。連接受力后，由于接觸面上產(chǎn)生的摩擦力，能在相當(dāng)大的荷載情況下阻止板件間的相對滑移。當(dāng)外力超

17、過了板間摩擦力后，板件間即產(chǎn)生相對滑動(dòng)。高強(qiáng)度螺栓摩擦型連接是以板件間出現(xiàn)滑動(dòng)為抗剪承載力極限狀態(tài)；而承壓型是允許板件產(chǎn)生相對滑移后螺栓受力，最后以螺栓被剪斷或擠壓破壞為抗剪承載力極限狀態(tài)。,(1) 彎曲屈曲：雙軸對稱工字型截面 (2) 扭轉(zhuǎn)屈曲：雙軸對稱十字型截面 (3) 彎扭屈曲：單軸對稱T型截面,Key 1: Buckling modes of strut,Design Principles of Steel Structure,4 Axial forced member,Key 2: Factors affecting column stability,Design Principle

18、s of Steel Structure,4 Axial forced member,Effect of residual stress in member (焊接殘余應(yīng)力) Initial out-of-straightness (初彎矩) Accidental non-concentric loading (初偏心) Different End Conditions (端部約束不同),Key 3: Checking of Axial forced member,Design Principles of Steel Structure,4 Axial forced member,（1）強(qiáng)度驗(yàn)

19、算,（2）剛度驗(yàn)算,Key 3: Checking of Axial forced member,Design Principles of Steel Structure,4 Axial forced member,（3）整體穩(wěn)定驗(yàn)算,（4）局部穩(wěn)定驗(yàn)算,Key 3: Design principles of Axial forced member,Design Principles of Steel Structure,4 Axial forced member,1）Equistability principle 雙向等穩(wěn),2）Width limb and thin wall 寬肢薄壁,3）

20、Manufacture saving of labor 制造省工,4） Connect convenient 連接方便,Key 1: Factor influencing Mcr,Design Principles of Steel Structure,5 Beams,(1) EIy , GIt , EIw , Mcr.,(2) Spacing of lateral supports in the compression flange of beam, l1, Mcr.,(4) Loading position (a) on cross section: On top flange (a0),

21、 Mcr .,(3) Loading pattern,(5) The stronger restraint, Mcr .,(6) Geometric parameter about asymmetric section (截面不對稱幾何特性), By: enlarges the compression flange of beam, Mcr .,Key 2: Situations not be needed to cal. O.S. of beams,Design Principles of Steel Structure,5 Beams,（1）有剛性鋪板密鋪在梁的受壓翼緣上并與其牢固連接，能

22、阻止受壓翼緣側(cè)向位移（截面扭轉(zhuǎn)）時(shí)。 （2）H型鋼或工字形截面簡支梁受壓翼緣自由長度與其寬度之比l1/b1不超過表5.3所列數(shù)值時(shí)。 （3）箱形截面簡支梁的截面尺寸h/b06且l1/b095(235/fy)時(shí)。,1.強(qiáng)度驗(yàn)算： 包括正應(yīng)力、剪應(yīng)力、局部壓應(yīng)力驗(yàn)算，對組合梁還要驗(yàn)算翼緣與腹板交界處的折算應(yīng)力。,(1) 正應(yīng)力,(2) 剪應(yīng)力,(3) 局部壓應(yīng)力,(4) 折算應(yīng)力,Design Principles of Steel Structure,5 Beams,Key 3: Checking of beams,2.剛度驗(yàn)算：,均布荷載下等截面簡支梁, 標(biāo)準(zhǔn)荷載下梁的最大撓度 受彎構(gòu)件的撓度

23、限值，按表規(guī)定采用,梁的最大撓度可用材料力學(xué)、結(jié)構(gòu)力學(xué)方法計(jì)算。,Design Principles of Steel Structure,5 Beams,Key 3: Checking of beams,3.整體穩(wěn)定驗(yàn)算：,(1) 判斷梁是否需要進(jìn)行整體穩(wěn)定驗(yàn)算。 (2) 如需要?jiǎng)t按照梁的截面類型選擇適當(dāng)?shù)挠?jì)算公式計(jì)算整體穩(wěn)定系數(shù)。 (3) 不論哪種情況算得的穩(wěn)定系數(shù)大于0.6，都應(yīng)采用修正公式進(jìn)行修正。,(4) 采用公式驗(yàn)算整體穩(wěn)定承載力是否滿足要求。,Design Principles of Steel Structure,5 Beams,Key 3: Checking of beams,4.局部穩(wěn)定驗(yàn)算：,) 對于焊接組合梁，翼緣可以通過限制板件寬厚比保 證其不發(fā)生局部失穩(wěn)。 ) 腹板則較為復(fù)雜，一種方法是通過設(shè)置加勁肋的方 法保證其不發(fā)生局部失穩(wěn)；另一種方法是允許腹板 發(fā)生局部失穩(wěn)，利用其屈曲后承載力。,Design Principles of Steel Structure,5 Beams,Key 3: Checking of beams,(1) The GB code prov