Investigation of the Impact of Dual-Lane Axle Spacing on Lateral Load Distribution, 2016

(2016) Investigation of the Impact of Dual-Lane Axle Spacing on Lateral Load Distribution, 2016. Transportation, Department of

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Abstract

The spacing of adjacent wheel lines of dual-lane loads induces different lateral live load distributions on bridges, which cannot be determined using the current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) or Load Factor Design (LFD) equations for vehicles with standard axle configurations. Current Iowa law requires dual-lane loads to meet a five-foot requirement, the adequacy of which needs to be verified. To improve the state policy and AASHTO code specifications, it is necessary to understand the actual effects of wheel-line spacing on lateral load distribution. The main objective of this research was to investigate the impact of the wheel-line spacing of dual-lane loads on the lateral load distribution on bridges. To achieve this objective, a numerical evaluation using two-dimensional linear elastic finite element (FE) models was performed. For simulation purposes, 20 prestressed-concrete bridges, 20 steel bridges, and 20 slab bridges were randomly sampled from the Iowa bridge database. Based on the FE results, the load distribution factors (LDFs) of the concrete and steel bridges and the equivalent lengths of the slab bridges were derived. To investigate the variations of LDFs, a total of 22 types of single-axle four-wheel-line dual-lane loads were taken into account with configurations consisting of combinations of various interior and exterior wheel-line spacing. The corresponding moment and shear LDFs and equivalent widths were also derived using the AASHTO equations and the adequacy of the Iowa DOT five-foot requirement was evaluated. Finally, the axle weight limits per lane for different dual-lane load types were further calculated and recommended to complement the current Iowa Department of Transportation (DOT) policy and AASHTO code specifications.

Item Type: Departmental Report
Keywords: Axle weight limits, bridge loads, dual-lane axle spacing, lateral load distributions, load distribution factors, oversize permits, overweight permits
Subjects: Transportation
Transportation > Bridges and tunnels
Transportation > Motor vehicles
Transportation > Motor vehicles > Trucks
Transportation > Trucking and freight
Transportation > Research
Transportation > Design and Construction
Transportation > Maintenance and preservation
ID Code: 22240
Deposited By: Iowa DOT Library
Deposited On: 02 Jun 2016 12:37
Last Modified: 02 Jun 2016 12:37
URI: http://publications.iowa.gov/id/eprint/22240