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*Steel bridge of The Tomei Expessway(at sole plate) [#n8429ca7] *東名高速道路の鋼橋（ソールプレート）[#n8429ca7] **1.Field of application [#x5f9fe82] >Steel bridge on the roadway bridge,Japan.&br; >鋼道路橋.&br; **2.Circumstances of Repair [#kffdf54e] >Fatigue cracks were found in the sole plate welds at the girder support locations in 1990 after 22 years of service. >供用開始から22年が経過した1990年、主桁支点部のソールプレートの溶接部に疲労き裂が見つかった。 **3.Types of structure [#la0108b0] >The outline of the bridge structure is as follows.&br; >橋梁の構造諸元は次のとおりである。 -Bridge length : 114.864m -Span length : 35.0m+44.0m+35.0m -Structure : Three spans continuous girder bridge. -Structural steel : SM490A,SM490B,SS400 &br; -橋長：114.864m -支間長：35.0+44.0+35.0m -橋梁形式：3径間連続鈑桁橋 **4.Details of loading [#hf7aeb29] >Fluctuating loads due to highway live load. >活荷重 **5.Description of damage [#u45a91e0] >The location where the fatigue cracks were found were as follows.&br; >疲労き裂は以下の部位で発見された。 -The fillet welding joint at the front side of the sole plate(Type-1). -The fillet welding joint between the lower flange and the web(Type-2). -ソールプレート前面のすみ肉溶接部（Type-1） -下フランジとWEB間のすみ肉溶接部（Type-2） >Type-1 crack penetrated the lower flange.The length of type-2 crack was 200mm. >Type-1のき裂は下フランジを貫通し、き裂長200mmまで進展した。 CENTER:&aname(fig1);&attachref(./sole_plate_1.jpg,20%);&br; &br; CENTER:Fig.1 Crack location.&br; &br; CENTER:図.1 疲労き裂の位置.&br; &br; >Causes of fatigue cracks were as follows: >疲労き裂の原因は以下のとおりである。 -Stress concentration at the front side of sole plate that due to the lost of the rotation function of the bearing support caused by corrosion([[Fig.2(a)>#fig2]]). -Stress concentration at the welding between the lower flange and the web plate that was caused by the gap that occurred at the time of fabrication([[Fig.2(b)>#fig2]]). -腐食によって支承の回転機能が失われ、そのためにソールプレート前面に応力集中が生じた([[図.2(a)>#fig2]]). -製作過程でソールプレートと下フランジに隙間が生じ、そのため下フランジとWEB間のすみ肉溶接部に応力集中が生じた([[図.2(b)>#fig2]]). CENTER:&aname(fig2);&attachref(./sole_plate_2.jpg,40%);&br; &br; CENTER:Fig.2 Causes of the cracks.&br; &br; CENTER:図.2 疲労き裂の原因&br; &br; **6.Repair method applied [#m7ca0d2c] >Emergency repair &br; >応急的処置&br; >At first, H-steel was inserted just under the lower flange.The main girder was supported by jack up after the partial repair that the temporary brackets and the temporary stiffener were installed to the web plate of the main girder. &br; >仮受け用のブラケットと補剛材を主桁に取り付け、主桁の下に設置したH形鋼をジャッキアップして主桁を支持した。 &br; >Permanent repair &br; >恒久的処置 +The cracks were repaired by full penetration welding after gouging. +The reinforcement plate was bolted with the lower flange to decrease the gap([[Fig.3(a)>#fig3]]). +The reinforcement plate with rib plate was bolted with the web to decrease the stress at the location of the crack([[Fig.3(b)>#fig3]]). +At the same time, the work to recover the function of the bearing supports was done. &br; +疲労き裂をガウジングで除去したのち、完全溶け込み溶接で補修した。 +隙間を少なくするため、下フランジに補強板を高力ボルトで固定した。 +疲労き裂位置での応力を低減させるため、WEBにリブ付き補強板を高力ボルトで固定した。 +同時に、支承の機能回復のための作業も行った。 CENTER:&aname(fig3);&attachref(./sole_plate_3.jpg,35%);&br; &br; CENTER:Fig.3 Permanent repair.&br; &br; CENTER:図.3 恒久的処置.&br; &br; **Reference [#aaa10bc7] >Watanabe et al, Fatigue damage and effect of repair at welding of sole plate,'''Prc.of Annual Conferenece of JSCE''',vol.51,1996.(In Japanese)
