Curved Bridges

Curved Bridges – Descus I for plate girders and Descus II for box girders

Abstract

The computer program DESCUS I will perform the complete analysis and partial design of a horizontally curved bridge composed of flanged steel sections which act either compositely or noncompositely with a concrete deck. The program can be run using either Working Stress Design (WSD) method, Load Factor Design (LFD) method or the LRFD specifications for curved girders. DESCUS I incorporates the LRFD loadings. The bridge may be of arbitrary plan configuration and can be continuous and skewed over supports. The girders may have high degree of curvature, may be nonconcentric, bifurcated, and may contain hinges.

Program Scope

The program models the bridge structure as a two-dimensional grid in a stiffness format with three degrees-of-freedom at each nodal point (corresponding torsion, shear, and bending moment). All nodal locations, member connectivity, and section properties are generated internally from basic input. All dead load (DL) computations are performed automatically within the program to satisfy the construction conditions specified by AASHTO. Additional constant dead load is allowed input per girder as a special program option. All live load (LL) computations also are performed automatically where the AASHTO truck and lane loadings are applied to an influence surface previously generated for the entire bridge. Impact (I) effects also are included per AASHTO recommendations. Up to nine arbitrary trucks can also be specified and analyzed concurrently.

Output contains the positive and negative maximum moments, shears, and torsion along with the corresponding primary and warping stresses for each girder and beam or truss diaphragm element. These maxima are given along with all AASHTO group combinations for DL + LL + I. Also output are deformations along each girder for DL and maximum LL + I, along with the allowable recommended by AASHTO. Finally, various tables are output which yield information on the design of the sections including maximum stresses, allowable stresses, shear ranges, shear connector, and stiffener spacings.

The program runs using Windows operating system for both single user and Network versions.

New Graphical Displays

3-dimensional model of input nodes and members for easy verification of the structural model and a solid model rendering.

Construction Staging

Construction staging is an integrated utility program designed specifically for the construction staging of a curved steel bridge. Program will read program input from the DESCUS I program with additional data for construction staging to investigate effects of a curved girder bridge during construction.

Descus II

Abstract

The computer program DESCUS II will perform the complete analysis of a horizontally curved bridge composed of steel box sections which act either compositely or noncompositely with a concrete deck. The program can use either the Working Stress Design (WSD) method, the Load Factor Design method or the Load Resistance Factor Design (LRFD) method. DESCUS II has incorporated the LRFD loadings. The bridge may be of arbitrary plan configuration and can be continuous and skewed over supports. The box girders may have a high degree of curvature and may be non-concentric.

Program Scope

The program models the bridge structure as a two-dimensional grid in a stiffness format with three degrees-of-freedom at each nodal point (corresponding to torsion, shear, and bending moment). All nodal locations, member connectivity, and properties are generated internally from basic input. All dead load (DL) computations are performed automatically within the program to satisfy the construction conditions specified by AASHTO. Additional dead load (DL) and superimposed dead load (SDL) are allowed to input to combine with the program-generated dead load. All live load (LL) computations also are performed automatically where the AASHTO truck and lane loadings are applied to an influence surface previously generated for the entire bridge.

Output contains the positive and negative maximum moments, shears, reactions, and torsion along with the corresponding primary and warping stresses for each girder and beam or box diaphragm element. These maxima are given along with all AASHTO group combinations for DL + LL + I. Also output are deformations along each girder for DL and maximum LL + I. Various tables are output which yield information on the design of the sections including stresses and shear ranges. Finally, tables for bottom flange allowable normal stresses with actual torsional shear stress based on the AASHTO Specifications.

The program runs using Windows operating system for both single user and Network versions.

New Graphical Displays

3-dimensional model of input nodes and members for easy verification of the structural model and a solid model rendering.

Construction Staging

Construction staging is an integrated utility program designed specifically for the construction staging of a curved steel bridge. Program will read program input from the DESCUS II program with additional data for construction staging to investigate effects of a curved girder bridge during construction.