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*Haseltalbrucke Bridge [#kded4cff] **1.Field of application [#t65260d7] >Haseltalbrucke bridge on Bayern, Germany. **2.Circumstances of repair [#r903660f] >Fatigue cracks were found in the groove welds of the longitudinal ribs and in the vertical stiffener welds at the floorbeam connections in 1983 after 25 years of service. **3.Types of structure [#u1e1b913] >This bridge is curved (R=2000) bridge with steel plate floor which consists of two plate girders. Elevation is shown in [[figure 1>#fig1]], the cross section is in [[figure 2>#fig2]] and the side view is in [[figure 3>#fig3]]. Both ends of the longitudinal ribs under the steel plate floor were weld connected to the floorbeams. The floorbeams were fillet weld connected to the vertical stiffeners. The structural steel is St 52-3 and St 37-2. &br; CENTER:&aname(fig1);&attachref(Haselt1.gif);&br; &br; CENTER:Fig.1 Elevation view (m). &br; &br; CENTER:&aname(fig2);&attachref(Haselt2.gif);&br; &br; CENTER:Fig.2 Cross section (mm). &br; &br; CENTER:&aname(fig3);&attachref(Haselt3.gif);&br; &br; CENTER:Fig.3 Side view (mm). &br; **4.Details of loading [#kfae7600] >Fluctuating loads due to highway live load. **5.Description of damage [#fef1da6a] >Fatigue cracks occurred in the groove welds of the longitudinal ribs and in the vertical stiffener welds at the floor beam connections ([[Fig.4>#fig4]],[[5>#fig5]],[[6>#fig6]]). The cracks were classified in 5 types as shown in [[figure 4>#fig4]]. >Causes of fatigue cracks were as follows: -Luck of the weld strength at the connections. -Lack of the weld strength at the connections. -Action of the bending moment at the girder-floor beam connections. &br; CENTER:&aname(fig4);&attachref(Haselt4.gif);&br; CENTER:&aname(fig4);&attachref(Haselt5.gif);&br; &br; CENTER:Fig.4 Crack location. &br; &br; CENTER:&aname(fig5);&attachref(Haselt6.gif);&br; &br; CENTER:Fig.5 Crack at the groove weld of the floor beam web-flange connection (Type C). &br; &br; CENTER:&aname(fig6);&attachref(Haselt7.gif);&br; &br; CENTER:Fig.6 Crack at the fillet weld connection (Type D). &br; **6.Repair method applied [#waf2ec85] >For the cracks of the vertical stiffener welds, repair was performed by re-welding. >For the cracks of the longitudinal ribs, firstly, half depth plates of the ribs were weld connected ([[Fig.7>#fig7]],[[8>#fig8]]). Secondary, full depth plates of the ribs were bolt connected to the floor beam webs by using cover plates and were weld connected to the steel plate floor ([[Fig.9>#fig9]]). >As the improvement of structural detail, Two longitudinal truss structures were constructed between the girders ([[Fig.10>#fig10]],[[11>#fig11]]) and transverse truss bracings were constructed at 9.24 spaces ([[Fig.12>#fig12]]). &br; CENTER:&aname(fig7);&attachref(Haselt8.gif);&br; &br; CENTER:Fig.7 Weld connection of half depth plates of the ribs. &br; &br; CENTER:&aname(fig8);&attachref(Haselt15.gif);&br; &br; CENTER:Fig.8 Connection view of half depth plates of the ribs. &br; &br; CENTER:&aname(fig9);&attachref(Haselt10.gif);&br; &br; CENTER:Fig.9 Connection of full depth plates of the ribs. &br; &br; CENTER:&aname(fig10);&attachref(Haselt11.gif);&br; &br; CENTER:Fig.10 Connection of the longitudinal truss at the ribs. &br; &br; CENTER:&aname(fig11);&attachref(Haselt14.gif);&br; &br; CENTER:Fig.11 Connection view of the longitudinal truss. &br; &br; CENTER:&aname(fig12);&attachref(Haselt6.gif);&br; &br; CENTER:Fig.12 Truss structure view. &br; **Reference [#v9f776f4] >Schwerber L., Hofmanu U. R., Die Haseltalbrucke, Der Stahlbau 33, Heft 6, S, 168-177, 1964. >Nather Fr., Erfahruugen mit der Sanierung und Verstarkung stahlerner Staßeubrucken, Baukultur, Heft 5, S,44-50,1990. &br; &br;
