In this paper a mathematical model for the combined system of framed tube, shear core and belt truss is developed with the objective of determining the optimum location of belt truss along the height of the building. The effect of belt truss and shear core on a framed tube is considered as a concentrated moment at the belt truss location. This concentrated moment acts in a direction opposite to rotation due to lateral loads. The axial deformation functions for web and fl ange of the frames are considered to be quadratic and cubic functions, respectively; developing their stress relations and minimizing the total potential energy of the structure with respect to the lateral defl ection (u), rotation of the plane section (f) and unknown coeffi cients of shear lag (a 1 , a 2 , b 1 and b 2 ), the mathematical model is developed. This model yields the displacement, axial stress distribution and bending stiffness as a function of the height of the combined system. The range application and validity of the proposed model is demonstrated by several numerical examples (30-, 40-and 50-storey buildings). The effects of belt truss position on lateral displacement and stress distribution are investigated and the optimum location for belt truss is obtained. basic form, the system consists of closely spaced exterior columns along the periphery interconnected by deep spandrel beams at each fl oor. This produces a system of rigidly connected jointed orthogonal frame panels forming a rectangular tube, which acts as a cantilevered hollow box according to classical beam theory.A relatively new concept that has evolved within the past two decades is the technique of using a belt truss on a braced core combined with exterior columns. In this system, columns are tied to the belt trusses. Therefore, in addition to the traditional function of supporting gravity loads, the columns restrain the lateral movement of the building. When the building is subjected to lateral forces, tie-down action of the belt truss restrains bending of the shear core by introducing a point of infl ection in its defl ection curve. This reversal in curvature reduces the lateral movement at the top. The belt trusses function as horizontal fascia stiffeners and engage the exterior columns, which are not directly connected to the outrigger belt truss. If a building is to have one or more fl oors devoted to mechanical equipment, rather than lease space, large belt or outrigger trusses can be placed in the perimeter, one storey in height (

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High rise structures are more vulnerable to earthquake loads. Hence to build this high rise structures stable an external frame works is required to increase its resistance against the seismic tremor one of such system is the belt truss systems. In this study, the response of steel tubular structures with and without the belt truss systems subjected to earthquake forces is evaluated under the seismic zone V considering 70 storey steel tubular structures for analysis. The analytical method used in this dissertation work is Time History Method. Time history analysis is performed by using BHUJ earthquake data. The software utilized for the analysis is ETABS v 9.7.4. Also, the location of belt truss in the tube in tube and framed tube structures and comparison of these steel tubular structures with the steel moment resisting frames are carried out. In this work, various parameters like storey drifts, storey displacements, time period and base shear has been evaluated for different models and have been compared to obtain an efficient structure.

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Deteriorated bridges are subjected to time-variant changes of resistance. Corrosion is one of the most important types of deterioration in steel bridges. The consequence is a reduction in safety of a bridge. Therefore, it is needed to evaluate procedures for an accurate prediction of the load-carrying capacity and reliability of corroded bridges, in order to make rational decisions about repair, renewal or rehabilitation. This paper presents a highway bridge reliability-based design formulation which accounts for pitting corrosion effects on steel box girder bridges. The study involves the idealization of pitting corrosion, development of resistance models for corroded steel box girders, development of load models, formulation of limit state function, development of reliability analysis method, and development of the time-dependent reliability for corroded steel girders. Numerical example illustrates the application of the proposed approach. The results of this study can be used for the better prediction of the service life of deteriorating steel box girder bridges and the development of optimal reliability-based maintenance strategies.