变形引起的疲劳、腐蚀、腐蚀疲劳_-John_W._Fisher

Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 1 Advanced Technology for Large Structural Systems Center Lehigh University Fatigue and Fracture Fatigue and Fracture Fatigue and Fracture Fatigue and Fracture Design of Steel BridgesDesign of Steel BridgesDesign of Steel BridgesDesign of Steel Bridges - Distortion Induced Fatigue 变形引起的疲劳 变形引起的疲劳变形引起的疲劳 变形引起的疲劳 - Corrosion/corrosion Fatigue 腐蚀引起的疲劳 腐蚀引起的疲劳腐蚀引起的疲劳 腐蚀引起的疲劳 Advanced Technology for Large Structural Systems Center Lehigh University Load vs. DisplacementLoad vs. DisplacementLoad vs. DisplacementLoad vs. DisplacementLoad vs. DisplacementLoad vs. DisplacementLoad vs. DisplacementLoad vs. Displacement 荷载和变位荷载和变位荷载和变位荷载和变位荷载和变位荷载和变位荷载和变位荷载和变位 � Load induced fatigue 荷载引起的疲劳 荷载引起的疲劳荷载引起的疲劳 荷载引起的疲劳 – Detail primarily subjected to in-plane stresses 主要受面内应力 主要受面内应力主要受面内应力 主要受面内应力; out-of-plane bending component due to element deformation negligible 面外弯曲可忽略 面外弯曲可忽略面外弯曲可忽略 面外弯曲可忽略 � Distortion (displacement) induced fatigue 变形引起的疲劳 变形引起的疲劳变形引起的疲劳 变形引起的疲劳 – Secondary stresses generated due to deformation of element either from secondary out of plane deformation and/or second order load-deformation interaction 二次应力 二次应力二次应力 二次应力 • Secondary deformation arises due to incompatibility in displacement between connecting elements • In plane stresses interact with out-of-plane deformation to cause second order stresses Advanced Technology for Large Structural Systems Center Lehigh University Examples of Secondary StressesExamples of Secondary StressesExamples of Secondary StressesExamples of Secondary StressesExamples of Secondary StressesExamples of Secondary StressesExamples of Secondary StressesExamples of Secondary Stresses 二次应力举例 二次应力举例二次应力举例 二次应力举例二次应力举例 二次应力举例二次应力举例 二次应力举例 � “Oil canning” or “pumping” of flexible plates in bending 受弯柔性板的“颤动” 受弯柔性板的“颤动”受弯柔性板的“颤动” 受弯柔性板的“颤动” – Occurs without any lateral forces applied • Primarily due to geometric imperfection (out of flatness) – Sometimes visible � Out-of-plane distortion due to lateral forces or displacements 横向力下的面外变形 横向力下的面外变形横向力下的面外变形 横向力下的面外变形 – Web-gap cracking at local details • Floor beams and diaphragms – Deck plate cracking • Orthotropic bridge decks – Tie girder floor beam connections in arches • Also at floor beam connections in trusses and plate girder bridges – Cantilever bracket tie plates Advanced Technology for Large Structural Systems Center Lehigh University Small Web Gap CrackingSmall Web Gap CrackingSmall Web Gap CrackingSmall Web Gap CrackingSmall Web Gap CrackingSmall Web Gap CrackingSmall Web Gap CrackingSmall Web Gap Cracking 小间隙腹板裂纹 小间隙腹板裂纹小间隙腹板裂纹 小间隙腹板裂纹小间隙腹板裂纹 小间隙腹板裂纹小间隙腹板裂纹 小间隙腹板裂纹 � Floor beam connection plate not connected to flanges (concerns about welding to tension flange) – Small deformable web gap at connection plate cope Advanced Technology for Large Structural Systems Center Lehigh University WebWebWebWebWebWebWebWeb--------gap Crackinggap Crackinggap Crackinggap Crackinggap Crackinggap Crackinggap Crackinggap Cracking –––––––– Cross Frame ConnectionCross Frame ConnectionCross Frame ConnectionCross Frame ConnectionCross Frame ConnectionCross Frame ConnectionCross Frame ConnectionCross Frame Connection 横撑结点处 横撑结点处横撑结点处 横撑结点处横撑结点处 横撑结点处横撑结点处 横撑结点处 Advanced Technology for Large Structural Systems Center Lehigh University WebWebWebWebWebWebWebWeb--------gap Crackinggap Crackinggap Crackinggap Crackinggap Crackinggap Crackinggap Crackinggap Cracking –––––––– Long. Stiffener EndLong. Stiffener EndLong. Stiffener EndLong. Stiffener EndLong. Stiffener EndLong. Stiffener EndLong. Stiffener EndLong. Stiffener End 纵向加劲肋端部 纵向加劲肋端部纵向加劲肋端部 纵向加劲肋端部纵向加劲肋端部 纵向加劲肋端部纵向加劲肋端部 纵向加劲肋端部 Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 2 Advanced Technology for Large Structural Systems Center Lehigh University Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking -------- Top FlangeTop FlangeTop FlangeTop FlangeTop FlangeTop FlangeTop FlangeTop Flange 上翼缘 上翼缘上翼缘 上翼缘上翼缘 上翼缘上翼缘 上翼缘 WebWebWebWeb FlangeFlangeFlangeFlange Trans. Trans. Trans. Trans. Conn. Conn. Conn. Conn. PlatePlatePlatePlate Advanced Technology for Large Structural Systems Center Lehigh University Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking ––––––––Top FlangeTop FlangeTop FlangeTop FlangeTop FlangeTop FlangeTop FlangeTop Flange 上翼缘上翼缘上翼缘上翼缘上翼缘上翼缘上翼缘上翼缘 � Stress Reversal 反向应力 反向应力反向应力 反向应力 Advanced Technology for Large Structural Systems Center Lehigh University Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking Web Gap Cracking -------- Bottom FlangeBottom FlangeBottom FlangeBottom FlangeBottom FlangeBottom FlangeBottom FlangeBottom Flange 下翼缘 下翼缘下翼缘 下翼缘下翼缘 下翼缘下翼缘 下翼缘 Advanced Technology for Large Structural Systems Center Lehigh University Crack Development on Both SidesCrack Development on Both SidesCrack Development on Both SidesCrack Development on Both SidesCrack Development on Both SidesCrack Development on Both SidesCrack Development on Both SidesCrack Development on Both Sides 裂纹在两侧发展 裂纹在两侧发展裂纹在两侧发展 裂纹在两侧发展裂纹在两侧发展 裂纹在两侧发展裂纹在两侧发展 裂纹在两侧发展 Advanced Technology for Large Structural Systems Center Lehigh University Tie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam Cracking 系梁和桁架横梁处的裂纹 系梁和桁架横梁处的裂纹系梁和桁架横梁处的裂纹 系梁和桁架横梁处的裂纹系梁和桁架横梁处的裂纹 系梁和桁架横梁处的裂纹系梁和桁架横梁处的裂纹 系梁和桁架横梁处的裂纹 WebWebWebWeb Top Top Top Top flangeflangeflangeflange Connection Connection Connection Connection angleangleangleangle � Result of Relative Movement between Structure and Floor beams Advanced Technology for Large Structural Systems Center Lehigh University Tie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam CrackingTie Girder / Truss Floor beam Cracking Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 3 Advanced Technology for Large Structural Systems Center Lehigh University Cantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection Cracking 悬臂支撑结点裂纹 悬臂支撑结点裂纹悬臂支撑结点裂纹 悬臂支撑结点裂纹悬臂支撑结点裂纹 悬臂支撑结点裂纹悬臂支撑结点裂纹 悬臂支撑结点裂纹 Advanced Technology for Large Structural Systems Center Lehigh University Cantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection Cracking Advanced Technology for Large Structural Systems Center Lehigh University Cantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection CrackingCantilever Bracket Connection Cracking At Small Gaps 小间隙处 小间隙处小间隙处 小间隙处 Advanced Technology for Large Structural Systems Center Lehigh University Mitigation MeasuresMitigation MeasuresMitigation MeasuresMitigation MeasuresMitigation MeasuresMitigation MeasuresMitigation MeasuresMitigation Measures 缓解措施缓解措施缓解措施缓解措施缓解措施缓解措施缓解措施缓解措施 � Displacement induced fatigue cracking � Account for secondary stresses 考虑二次应力 考虑二次应力考虑二次应力 考虑二次应力 – Conduct advanced analysis and/or measurements � Essentially two mitigation approach 两种基本方法 两种基本方法两种基本方法 两种基本方法 – Stiffening 刚化 刚化刚化 刚化 – Softening 软化 软化软化 软化 – Hole drilling not effective !!! 钻孔并不有效！！！ 钻孔并不有效！！！钻孔并不有效！！！ 钻孔并不有效！！！ 2 6 L EIM ∆= Advanced Technology for Large Structural Systems Center Lehigh University Hole Drilling at FloorbeamsHole Drilling at FloorbeamsHole Drilling at FloorbeamsHole Drilling at FloorbeamsHole Drilling at FloorbeamsHole Drilling at FloorbeamsHole Drilling at FloorbeamsHole Drilling at Floorbeams 横梁上钻孔横梁上钻孔横梁上钻孔横梁上钻孔横梁上钻孔横梁上钻孔横梁上钻孔横梁上钻孔 Girder Girder Girder Girder WebWebWebWeb Floorbeam Floorbeam Floorbeam Floorbeam Connection PLConnection PLConnection PLConnection PL Not always effective; however drill holes to remove crack tip Advanced Technology for Large Structural Systems Center Lehigh University Temporary RetrofitsTemporary RetrofitsTemporary RetrofitsTemporary RetrofitsTemporary RetrofitsTemporary RetrofitsTemporary RetrofitsTemporary Retrofits 临时性修复临时性修复临时性修复临时性修复临时性修复临时性修复临时性修复临时性修复 Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 4 Advanced Technology for Large Structural Systems Center Lehigh University Hole Drilling and StiffeningHole Drilling and StiffeningHole Drilling and StiffeningHole Drilling and StiffeningHole Drilling and StiffeningHole Drilling and StiffeningHole Drilling and StiffeningHole Drilling and Stiffening 钻孔和加固钻孔和加固钻孔和加固钻孔和加固钻孔和加固钻孔和加固钻孔和加固钻孔和加固 Here hole drilling was not effective; Stiffened connection 钻孔无效；须加固 钻孔无效；须加固钻孔无效；须加固 钻孔无效；须加固 Advanced Technology for Large Structural Systems Center Lehigh University Web Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. StiffenersWeb Gap Cracking at Long. Stiffeners 纵向加劲肋间隙裂纹 纵向加劲肋间隙裂纹纵向加劲肋间隙裂纹 纵向加劲肋间隙裂纹纵向加劲肋间隙裂纹 纵向加劲肋间隙裂纹纵向加劲肋间隙裂纹 纵向加劲肋间隙裂纹 � Retrofit with crack stopper (two holes connected with a slit: dog-bone shape) � 棒骨形钻孔 棒骨形钻孔棒骨形钻孔 棒骨形钻孔 Advanced Technology for Large Structural Systems Center Lehigh University Bottom Flange StiffeningBottom Flange StiffeningBottom Flange StiffeningBottom Flange StiffeningBottom Flange StiffeningBottom Flange StiffeningBottom Flange StiffeningBottom Flange Stiffening 下翼缘加固下翼缘加固下翼缘加固下翼缘加固下翼缘加固下翼缘加固下翼缘加固下翼缘加固 Rigidity of the retrofit is critical to success 刚性是关键 刚性是关键刚性是关键 刚性是关键 Advanced Technology for Large Structural Systems Center Lehigh University Retrofit by Stiffened Floor SystemRetrofit by Stiffened Floor SystemRetrofit by Stiffened Floor SystemRetrofit by Stiffened Floor SystemRetrofit by Stiffened Floor SystemRetrofit by Stiffened Floor SystemRetrofit by Stiffened Floor SystemRetrofit by Stiffened Floor System 加固横梁 加固横梁加固横梁 加固横梁加固横梁 加固横梁加固横梁 加固横梁 Advanced Technology for Large Structural Systems Center Lehigh University Softening with Large Web GapsSoftening with Large Web GapsSoftening with Large Web GapsSoftening with Large Web GapsSoftening with Large Web GapsSoftening with Large Web GapsSoftening with Large Web GapsSoftening with Large Web Gaps 加大腹板间隙进行软化 加大腹板间隙进行软化加大腹板间隙进行软化 加大腹板间隙进行软化加大腹板间隙进行软化 加大腹板间隙进行软化加大腹板间隙进行软化 加大腹板间隙进行软化 Permits out-of-plane displacement to occur over longer length or web gap (L) Must be sufficiently flexible to be successful 需足够柔软 需足够柔软需足够柔软 需足够柔软 Advanced Technology for Large Structural Systems Center Lehigh University Connection Softening Connection Softening Connection Softening Connection Softening Connection Softening Connection Softening Connection Softening Connection Softening –––––––– ExampleExampleExampleExampleExampleExampleExampleExample 结点软化实例 结点软化实例结点软化实例 结点软化实例结点软化实例 结点软化实例结点软化实例 结点软化实例 Quality control is critical Quality control is critical Quality control is critical Quality control is critical where connection plate is where connection plate is where connection plate is where connection plate is removedremovedremovedremoved Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 5 Advanced Technology for Large Structural Systems Center Lehigh University Connection SofteningConnection SofteningConnection SofteningConnection SofteningConnection SofteningConnection SofteningConnection SofteningConnection Softening 结点软化结点软化结点软化结点软化结点软化结点软化结点软化结点软化 Cantilever Bracket Connection softening by fastener removal 除去螺栓 除去螺栓除去螺栓 除去螺栓 Advanced Technology for Large Structural Systems Center Lehigh University Corrosion ConsiderationsCorrosion ConsiderationsCorrosion ConsiderationsCorrosion ConsiderationsCorrosion ConsiderationsCorrosion ConsiderationsCorrosion ConsiderationsCorrosion Considerations 腐蚀应考虑的因素腐蚀应考虑的因素腐蚀应考虑的因素腐蚀应考虑的因素腐蚀应考虑的因素腐蚀应考虑的因素腐蚀应考虑的因素腐蚀应考虑的因素 � Atmospheric corrosion resistance 环境 � Section loss from active corrosion cell activity from dirt, debris (with sulfates and chlorides) and moisture 尘土，废墟和潮气引起 � Changed structural function 改变结构功能 Advanced Technology for Large Structural Systems Center Lehigh University Open Bridge JointsOpen Bridge JointsOpen Bridge JointsOpen Bridge JointsOpen Bridge JointsOpen Bridge JointsOpen Bridge JointsOpen Bridge Joints 伸缩缝被打开伸缩缝被打开伸缩缝被打开伸缩缝被打开伸缩缝被打开伸缩缝被打开伸缩缝被打开伸缩缝被打开 Advanced Technology for Large Structural Systems Center Lehigh University Corrosion NotchCorrosion NotchCorrosion NotchCorrosion NotchCorrosion NotchCorrosion NotchCorrosion NotchCorrosion Notch 锈蚀缺口锈蚀缺口锈蚀缺口锈蚀缺口锈蚀缺口锈蚀缺口锈蚀缺口锈蚀缺口 Advanced Technology for Large Structural Systems Center Lehigh University Open Expansion Joint Open Expansion Joint Open Expansion Joint Open Expansion Joint Open Expansion Joint Open Expansion Joint Open Expansion Joint Open Expansion Joint –––––––– MianusMianusMianusMianusMianusMianusMianusMianus 伸缩缝 伸缩缝伸缩缝 伸缩缝伸缩缝 伸缩缝伸缩缝 伸缩缝断开 断开断开 断开断开 断开断开 断开 -------- 迈亚纳斯桥迈亚纳斯桥迈亚纳斯桥迈亚纳斯桥迈亚纳斯桥迈亚纳斯桥迈亚纳斯桥迈亚纳斯桥 Advanced Technology for Large Structural Systems Center Lehigh University Fatigue crack in pin at outside hangerFatigue crack in pin at outside hangerFatigue crack in pin at outside hangerFatigue crack in pin at outside hangerFatigue crack in pin at outside hangerFatigue crack in pin at outside hangerFatigue crack in pin at outside hangerFatigue crack in pin at outside hanger 外侧吊杆处栓销裂纹 外侧吊杆处栓销裂纹外侧吊杆处栓销裂纹 外侧吊杆处栓销裂纹外侧吊杆处栓销裂纹 外侧吊杆处栓销裂纹外侧吊杆处栓销裂纹 外侧吊杆处栓销裂纹 Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 6 Advanced Technology for Large Structural Systems Center Lehigh University Fractured segment that supported Fractured segment that supported Fractured segment that supported Fractured segment that supported Fractured segment that supported Fractured segment that supported Fractured segment that supported Fractured segment that supported outside hangeroutside hangeroutside hangeroutside hangeroutside hangeroutside hangeroutside hangeroutside hanger 支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分支承外吊杆的栓销的断裂部分 Advanced Technology for Large Structural Systems Center Lehigh University Corrosion PackoutCorrosion PackoutCorrosion PackoutCorrosion PackoutCorrosion PackoutCorrosion PackoutCorrosion PackoutCorrosion Packout 锈蚀堆集膨胀锈蚀堆集膨胀锈蚀堆集膨胀锈蚀堆集膨胀锈蚀堆集膨胀锈蚀堆集膨胀锈蚀堆集膨胀锈蚀堆集膨胀 Advanced Technology for Large Structural Systems Center Lehigh University Schematic of condition at failureSchematic of condition at failureSchematic of condition at failureSchematic of condition at failureSchematic of condition at failureSchematic of condition at failureSchematic of condition at failureSchematic of condition at failure 落桥时的状况 落桥时的状况落桥时的状况 落桥时的状况落桥时的状况 落桥时的状况落桥时的状况 落桥时的状况 Advanced Technology for Large Structural Systems Center Lehigh University Weld Cracking from Corrosion PackoutWeld Cracking from Corrosion PackoutWeld Cracking from Corrosion PackoutWeld Cracking from Corrosion PackoutWeld Cracking from Corrosion PackoutWeld Cracking from Corrosion PackoutWeld Cracking from Corrosion PackoutWeld Cracking from Corrosion Packout 由锈蚀堆集膨胀产生的焊接裂纹 由锈蚀堆集膨胀产生的焊接裂纹由锈蚀堆集膨胀产生的焊接裂纹 由锈蚀堆集膨胀产生的焊接裂纹由锈蚀堆集膨胀产生的焊接裂纹 由锈蚀堆集膨胀产生的焊接裂纹由锈蚀堆集膨胀产生的焊接裂纹 由锈蚀堆集膨胀产生的焊接裂纹 Advanced Technology for Large Structural Systems Center Lehigh University Weld Cracking at Chord SpliceWeld Cracking at Chord SpliceWeld Cracking at Chord SpliceWeld Cracking at Chord SpliceWeld Cracking at Chord SpliceWeld Cracking at Chord SpliceWeld Cracking at Chord SpliceWeld Cracking at Chord Splice 弦杆拼接板处的焊接裂纹 弦杆拼接板处的焊接裂纹弦杆拼接板处的焊接裂纹 弦杆拼接板处的焊接裂纹弦杆拼接板处的焊接裂纹 弦杆拼接板处的焊接裂纹弦杆拼接板处的焊接裂纹 弦杆拼接板处的焊接裂纹 Advanced Technology for Large Structural Systems Center Lehigh University Crack in WeldCrack in WeldCrack in WeldCrack in WeldCrack in WeldCrack in WeldCrack in WeldCrack in Weld 焊接裂纹焊接裂纹焊接裂纹焊接裂纹焊接裂纹焊接裂纹焊接裂纹焊接裂纹 Session 3 Distorsion Induced fatigue; Corrosion Induced Fatigue 7 Advanced Technology for Large Structural Systems Center Lehigh University Corrosion packout created high stress Corrosion packout created high stress Corrosion packout created high stress Corrosion packout created high stress Corrosion packout created high stress Corrosion packout created high stress Corrosion packout created high stress Corrosion packout created high stress at weld rootat weld rootat weld rootat weld rootat weld rootat weld rootat weld rootat weld root 锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力锈蚀膨胀在焊根产生高应力 Advanced Technology for Large Structural Systems Center Lehigh University Corrosion PackCorrosion PackCorrosion PackCorrosion PackCorrosion PackCorrosion PackCorrosion PackCorrosion Pack--------outoutoutoutoutoutoutout 锈蚀堆集锈蚀堆集锈蚀堆集锈蚀堆集锈蚀堆集锈蚀堆集锈蚀堆集锈蚀堆集 Advanced Technology for Large Structural Systems Center Lehigh University HPS Toughness & Corrosion HPS Toughness & Corrosion HPS Toughness & Corrosion HPS Toughness & Corrosion HPS Toughness & Corrosion HPS Toughness & Corrosion HPS Toughness & Corrosion HPS Toughness & Corrosion ResistanceResistanceResistanceResistanceResistanceResistanceResistanceResistance 高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性高性能钢的韧性和耐腐蚀性 � Actual toughness far exceeds the AASHTO requirements for fracture critical members. 远高于 远高于远高于 远高于 AASHTO对断裂敏感构件的韧性要求 对断裂敏感构件的韧性要求对断裂敏感构件的韧性要求 对断裂敏感构件的韧性要求 � Fracture mode changes from brittle fracture to yield on net section. 断裂模式由脆性断裂转向净截面屈服 断裂模式由脆性断裂转向净截面屈服断裂模式由脆性断裂转向净截面屈服 断裂模式由脆性断裂转向净截面屈服 � Enhanced crack tolerance increases the potential to detect cracks before failure. 裂纹容忍度提高从而提高了 裂纹容忍度提高从而提高了裂纹容忍度提高从而提高了 裂纹容忍度提高从而提高了 破坏前被查到的可能 破坏前被查到的可能破坏前被查到的可能 破坏前被查到的可能 � Fatigue resistance does not change 疲劳强度不变 疲劳强度不变疲劳强度不变 疲劳强度不变 � Weathering steel index is better than conventional weathering steel 耐候钢指数高于普通耐候钢 耐候钢指数高于普通耐候钢耐候钢指数高于普通耐候钢 耐候钢指数高于普通耐候钢 Advanced Technology for Large Structural Systems Center Lehigh University Thickness Loss After 2 YearsThickness Loss After 2 YearsThickness Loss After 2 YearsThickness Loss After 2 YearsThickness Loss After 2 YearsThickness Loss After 2 YearsThickness Loss After 2 YearsThickness Loss After 2 Years 22年后的厚度损失年后的厚度损失年后的厚度损失年后的厚度损失年后的厚度损失年后的厚度损失年后的厚度损失年后的厚度损失 Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG)Kure Beach 25m Location (ISG) - 1 2 3 0 2 4 6 8 10 12 A36 A588 HPS 70W 100W Kobe NKK NSC A1010 Co rr o si o n Lo ss , m ils G101 Townsend Index Advanced Technology for Large Structural Systems Center Lehigh University Comparison of Improved Weathering SteelsComparison of Improved Weathering SteelsComparison of Improved Weathering SteelsComparison of Improved Weathering SteelsComparison of Imp