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Two continuous lattice steel truss bridges spanning 190 m with subdivided top chord members were constructed on the same design across river Alaknanda at Dugadda and Srinagar, respectively, in Uttarakhand, India. Both bridges were similar in design and geometry having middle span of 110.0 m and two end spans of 40.0 m. Garudchatti bridge at Dugadda was constructed first and opened to traffic, but excessive vibrations and lifting of end supports under live load condition were observed. Construction of Chauras bridge at Srinagar started later, but it collapsed during casting of the deck slab due to buckling of one of its top chord compression members. Failure of Chauras bridge led to the serious concerns in the minds of people and technocrats about the safety of Garudchatti bridge also, because it was constructed using the same design of Chauras bridge. Therefore, it was decided to strengthen and carry out load testing of Garudchatti bridge before reopening to the traffic. In the present work analyses of Garudchatti bridge are presented to identify structurally unsafe members for most severe live loads given in IRC:6-2010 code, and recommendations for strengthening of the critical members. Finite element space frame analyses of the bridge were carried out using STAAD Pro. v8i software to find excessively stressed members beyond their permissible stress limit. The critical compression members were strengthened by welding additional channel sections. RCC anchor blocks were constructed to restrict lifting of end supports under live load. After strengthening, load testing of the bridge was performed to ensure the safety of the bridge. The bridge is now reopened for traffic. In the past a number of bridges have collapsed during load testing. In case of any shortcoming in the design or overloading during load testing, compression members of the truss may suddenly buckle and cause collapse of the bridge. Therefore, it is not advisable to load test steel truss bridges which do not have adequate margin beyond the service load condition. [ABSTRACT FROM AUTHOR]

This paper deciphers the late stress systems involved in the development of kink bands in the perspective of thrust regime. In kink bands, the correlation coefficient for α- β plots is positive near thrusts and negative away from thrusts. The plots show nearly linear relationship near thrusts and non-linear relationship away from thrusts. The rotation was prominent mechanism of kink band formation near thrusts and rotation coupled with shearing, along the kink planes away from thrusts. Along thrusts σ is horizontal E-W trend and it rotates to horizontal N-S trend away from the thrust. The proposed model establishes that (1) the shearing along kink planes led to angular relationship, β < α and (2) the kink planes of conjugate kinks could be used for paleostress analysis even in those cases where shearing along these planes has occurred. [ABSTRACT FROM AUTHOR]