Traffic Load Models for Latvian Road Bridges With Span Length up to 30 Meters

Abstract

Bridges are structures that propose the service life up to hundred years. However, the actual traffic load models significantly differ from the characteristic load models used in the design. The analysis of former design codes of bridges used in the last century in Latvia showed the considerable increase in values of characteristic traffic loads. The traffic loads proposed in Eurocode 1: Actions on Structures – Part 2: Traffic Loads on Bridges considerably increase the actual traffic loads passing Latvian bridges. Therefore, the use of the actual traffic load models for assessment of the load carrying capacity of the older bridges will extend the service life and save financial funds for the maintenance of the bridges. Earlier, the obtaining of the correct traffic data was complicated. Today after implementation of the Weight-in-Motion system, it is possible to collect vehicle information without interrupting traffic flow. This includes data of the number of axles, vehicle wheelbase, speed and axle loads that describes the actual loading cases on the roads and bridges. The analysis of the recorded data of Weight-in-Motion the system enabled to obtain the load distribution diagrams, to determine the position of the heaviest axel, traffic speed and intensity values. The obtained results of statistical analysis of actual traffic loads allowed developing the integrated traffic load models for bridges, based on actual traffic load in Latvia. Obtained integrated traffic load models for bridges in Latvia is used for evaluation of the value of the adjustment factor α of the load model LM1 proposed in Eurocode 1: Actions on Structures – Part 2: Traffic Loads on Bridges.