Nagesh R. Iyer

A four-stage procedure for effective management and maintenance scheduling for infrastructural facilities is presented. The structure/component needing immediate attention is identified during the first stage. The second stage investigations reveal local or global damage and also the location of damage, based on the principles of damage assessment. Nondestructive testing and evaluation form the third stage. In the last stage, repair and remedial measures are carried out, which are followed by testing, if necessary. Out of the case study examples presented, two are specific to the third and fourth stage evaluation only, while one case study example is explained in full.

The analytical deformation of a transmission line (TL) tower computed using software is less than the test deformation. A TL tower consists of many splice joints in the leg member. A small rotation owing to bolt slip in the joint may cause additional deformation in the tower, which is difficult to predict and cannot be accounted for in the analysis. Experimental studies are conducted on variation of bolt force with the applied torque and on bolt slip in butt-jointed specimens and the load at which it occurs. The actual behavior of the joints is studied on seven towers recently tested at the Tower Testing and Research Station of the Structural Engineering Research Centre, a national laboratory under the Council of Scientific and Industrial Research, Government of India. The bolt slip occurs when the axial force in the leg member exceeds the clamping force at that particular joint. On the basis of the studies conducted, a factor that gives the relationship between experimental and theoretical deform...

Transmission line towers, though designed per code provisions, may fail during mandatory testing required in many countries. Different types of premature failures that were observed during full-scale testing of transmission line towers at Tower Testing and Research Station, Structural Engineering Research Centre, Chennai (CSIR-SERC) are studied, and the results are discussed in detail. The failures are modeled using finite-element software, and the analytical results and the test results are compared with various code provisions. The nonlinear finite-element analysis program NE-Nastran was used to model the elastoplastic behavior of towers. Bracing members with slenderness ratios above 170 become ineffective, even though they have to carry insignificant forces. Importance of design assumptions and connection detailing in overall performance of towers were studied. Nonlinear finite-element analysis is useful in understanding the system behavior and for prediction of the failure pattern and ultimate load. B...