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*Two hinges arch bridge on roadway bridge [#pe109788] **1.Field of application [#ffba77bd] >Deck-type two hinges arch bridge on roadway bridge, Japan.&br; **2.Circumstances of Repair [#f8ab7ad2] >Fatigue cracks were found in the intermediate vertical member ends at the arch crown connections in 1981 after 16 years of service.&br; **3.Types of structure [#o2a2ee44] >The outline of the bridge structure is as follows. -Bridge length : 197.0m -Span length : 32.0m + (6.0m + 120.0m + 6.0m)+ 32.0m -Structure : Deck-type two hinges arch bridge, Gerber bridge -Deck : Reinforced concrete deck (19.0 cm thickness) -Structural steel : SS 41, SM 50, rivet SV 34, SV 41 &br; &br; >Elevation and cross section are shown in [[figure 1>#fig1]]. The number of the stiffening girders, which are spaced at 9.5m, is two. The top and bottom ends of the vertical member are bolt connected to the gusset plates which are fillet weld connected to the arch ribs and stiffening girders.&br; &br; &br; CENTER:&aname(fig1);&attachref(Twohin1.jpg);&br; &br; CENTER:Fig.1 Elevation and cross section.&br; &br; &br; **4.Details of loading [#uc33431a] >Fluctuating loads due to vehicles live load. **5.Description of damage [#k91a090e] >Fatigue cracks were found in the weld at the gusset plate connection with the stiffening girders and the arch ribs ([[Fig.2>#fig2]]). The cracks also occurred in the fillets of cut-out gussets ([[Fig.2>#fig2]]). One of them had propagated into the stiffening girder bottom flange. >Cause of fatigue cracks was thought as follows: -Notch of the fillets caused by gas cutting. &br; &br; CENTER:&aname(fig2);&attachref(Twohin2.jpg);&br; &br; CENTER:Fig.2 Crack locations.&br; **6.Repair method applied [#ff745bbe] >Emergency repair &br; >At the locations where the crack propagated in the stiffening girder flange, repair was performed by hole-drilling and splice joint by high strength bolts ([[Fig.3>#fig3]]). &br; &br; >Permanent repair &br; >Permanent repair was performed by improvement of the structural detail. The original intermediate vertical members were improved to new structure such as increasing the stiffness of the vertical member. In the damaged vertical member ends except for the intermediate vertical members, Pin connections were performed ([[Fig.4>#fig4]]).&br; &br; >At the inspection in 1990, it had not been reported that the crack re-initiated and propagated. &br; &br; CENTER:&aname(fig3);&attachref(Twohin3.jpg);&br; &br; CENTER:Fig.3 Emergency repair.&br; &br; &br; CENTER:&aname(fig4);&attachref(Twohin4.jpg);&br; &br; CENTER:Fig.4 Permanent repair..&br; CENTER:Fig.4 Permanent repair.&br; &br; &br;
