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*Shindenpo Bridge of Route 43 : Replacement and Bolt connecting [#v9e768fa] *Shindenpo Bridge of Route 43 [#v9e768fa] **1.Field of application [#v2e87d1d] >Shindenpo Bridge of Route 43, Osaka.&br; **2.Circumstances of Repair [#pb16a00e] >Fatigue cracks were found in the sol plate welds at the girder support locations in 1990 after 24 years of service. Inspection of the support indicated that repair was required.&br; **3.Types of structure [#w853f43b] >The outline of the bridge structure is as follows.&br; -Bridge length : 860.3m -Span length : 4＠66.6m+5＠65.5m+4＠66.6m (13 spans) -Structure : Simple composite two-box girder bridge -Deck : Reinforced concrete deck -Structural steel : Corresponding SM 50 (steel proof against climate) &br; &br; >Plan and cross section were shown in [[figure 1>#fig1]]. The interior of the box girders contains the diaphragms. Two pin supports are constructed per a box girder.&br; &br; &br; CENTER:&aname(fig1);&attachref(Shinde3.jpg);&br; &br; CENTER:Fig.1 Elevation plan and cross section.&br; &br; &br; **4.Details of loading [#i8e12d14] >Fluctuating loads due to vehicles live load. **5.Description of damage [#e6d6a681] >Fatigue cracking were found in the sole plate front welds at the girder supports. &br; >Most of the cracks initiated from the weld in front of the sole plate. Only a few cracks which initiated from the girder web-flange weld are observed. After penetrating through the girder bottom flange, the cracks which initiated from the welds in front of the sole plate had propagated at an angle in the girder web([[Fig.2>#fig2]]). At the time of discovery, Both the movable supports and the fixed bearings lost the function as supports and the subsidence of the shoe base was also observed. &br; &br; >Cause of fatigue cracks was as follows: -Stress concentration due to the subsidence and lost of the support function. &br; &br; CENTER:&aname(fig2);&attachref(Shinde4.jpg);&br; &br; CENTER:Fig.2 Crack propagating in the girder web from the sole plate weld.&br; &br; &br; **6.Repair method applied [#m90ed0d7] >As an emergency repair, temporary support bent was constructed for the cracks which propagated to the girder web.&br; &br; &br; >As a permanent repair, strengthening was as follow ([[Fig.3>#fig3]],[[4>#fig4]]). -Removing the pin support and replacing with new BP (Bearing plate) supports. -Replacing with the large sole plates and bolt-connecting to the girder bottom flange. -Bolt-splicing after being refilled by welding. &br; &br; CENTER:&aname(fig3);&attachref(Shinde5.jpg);&br; &br; CENTER:Fig.3 Permanent repair.&br; &br; &br; CENTER:&aname(fig4);&attachref(Shinde6.jpg);&br; &br; CENTER:Fig.4 Repair view.&br; &br; &br;
