Steel Pier with Box section on The Metropolitan Expressway の変更点

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Steel Pier with Box section on The Metropolitan Expressway へ行く。
Steel Pier with Box section on The Metropolitan Expressway の差分を削除
*Steel Pier with Box section on The Metropolitan Expressway [#g5f05733]
*首都高速道路の鋼製橋脚 [#g5f05733]

**1.Field of application [#r15ae1ab]

>Steel pier at The Third line on The Metropolitan Expressway, Japan.&br;
>首都高速道路3号線の鋼製橋脚.&br;

**2.Circumstances of Repair [#m6160cd1]

>Fatigue cracks were found in welded joints ,which were the corner of the steel bridge pier,in 1997.
>1997年、箱断面鋼製橋脚の角部の溶接継手に疲労き裂が見つかった。
>1997年、箱断面鋼製橋脚の隅角部の溶接継手に疲労き裂が見つかった。

**3.Types of structure [#k979f13d]

>Front views of the steel piers are shown in [[Fig.1>#fig1]].
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>[[図.1>#fig1]]に鋼製橋脚の正面図を示す.&br;

CENTER:&aname(fig1);&attachref(./pier_shutoko_1_R1.jpg,15%);&br;
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CENTER:Fig.1 Front of the steel piers
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CENTER:図.1 正面図
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**4.Details of loading [#s818a3f2]
>Fluctuating loads due to highway live load. 
>活荷重

**5.Description of damage [#y00eaa5f]
>One of these fatigue cracks location and detail are shown in [[Fig.2>#fig2]].
&br; 
>[[図.2>#fig2]]に、疲労き裂（抜粋）の位置と詳細を示す。
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CENTER:&aname(fig2);&attachref(./pier_shutoko_2.jpg,20%);&br;
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CENTER:Fig.2 One of these fatigue cracks location and detail
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CENTER:図.2 疲労き裂の位置と詳細
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>Causes of fatigue cracks were as follows:
>疲労き裂の原因は次のとおりである。
-Lack of fusion in the double bevel groove type welded joint which connected the transverse beam flange to the colum flange.
-Large cyclic stress due to live load.

-横梁と柱のフランジ間の両開先溶接部の溶け込み不良
-横梁と柱のフランジ間の両開先溶接部の溶け込み不足
-活荷重による高い繰り返し応力

**6.Repair method applied [#me675e4d]
>As the temporally-repair,bolted splice plates([[Fig.3>#fig3]]) were installed on the box webs of the connections.This repairing decreased the measured stress by about 50%,so that these piers could be used safely temporally.But it was needed to remove all the fatigue cracks as the final repair.
&br;
>応急的処置として、([[図.3>#fig3]])に示すとおり、WEBの当て板補強を行い高力ボルトで固定した。この当て板補強により、約50％の応力低減となり、安全に供用できる状態となった。

CENTER:&aname(fi3);&attachref(./pier_shutoko_3.jpg,20%);&aname(fi4);&attachref(./pier_shutoko_4.jpg,40%);&br;
CENTER:Fig.3 Bolted splice plates and Construction photograph of bolted splice plates
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CENTER:図.3 当て板補強とその施工状況
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**Reference [#b370504a]
>Hisashi MORIKAWA,Tetsuhiro SHIMOZATO,Chitoshi MIKI and Atsushi ICHIKAWA,STUDY ON FATIGUE CRACKING IN STEEL BRIDGE PIERS WITH BOX SECTION AND TEMPORALLY REPAIRING,'''Journal of JSCE''',No.703/I-59,pp177-183,2002.4(In Japanese)
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