"COMPUTER AIDED ANALYSIS OF CONCRETEBOX GIRDER BRIDGES FOR SECONDARY LOADS"

Abstract

In reinforced concrete bridge construction,various- types of decks are being used like beam decks, grid decks, slab decks, beam & slab decks, cellular decks etc. The present dissertation work consists of the development of analysis program for concrete box girder bridges for secondary loads. Three types of box girder bridges have been taken up for.analysis, viz; single cell, two. cell & three cell box, with both vertical as well as inclined webs. Secondary loads which have been considered are: a) Temperature effects b) Earthquake loads c) Wind loads For discretization of the structure grillage analysis has been used. The structure has been discretized into the. longitudinal members in. two mutually perpendicular directions. For analysis stifness approach has been adopted using the matrix notations. Basic outline _of.the dissertation work is as follows. The entire work is divided into four modules. They are: a) Modelling b) Loads c) Analysis and. d) Drafting Modelling and loads. modules act as preprocessor to analysis, whereas Drafting module is the post processor. Output of analysis part is used in the drafting program as input. Therefore the user is required to. execute two different programs. •This is. done to keep memory requirements under control as also to add flexibility for further use. (iv) The programming language used is FORTRAN-77 and runs on both UNIX & MS-DOS environments. Drafting part is done using PLOT88 software which is PC based. Output of drafting program consists of various types of sections ofbox, basic plan of box-girder bridge and discretized mesh. Output of the drafting part can be taken either on Dot m ;trix printer or Plotter For interpretation of analysis output "HPG" .(Hardward Presentation Graphics) software has been used for drawing various graphs. The program is divided into several subroutines which are called in the main. program for clarity of understanding and for easy handling & debugging of the program. Computer program has-been developed' for box girder bridge with straight and simply supported-span. The analysis program calculates member forces such as axial force, shear force, bending moment and torsional moment at various sections of the box-girder bridge. These values can be fed to some design software therefore. increasing, the flexibility of software for checking & rechecking the design. This analysis .software can be executed for various types of. box-sections & for various arrangements of box-girder bridge and then output can be -interpreted1-for arriving at some pertinent conclusions.