Some problems that arise when assessing the load capacity of road bridges in the process of field studies

   When studying the technical condition of road bridges in operation, the main and most difficult task is to obtain a correct assessment of the actual load capacity of the bridge. At the same time, problems arise that are mainly related to the insufficiency or lack of technical documentation for the construction, inconsistency of normative and methodological documents in terms of assessing the load capacity of bridges, uncertainty in the accounting of asphalt concrete pavement. In assessing the actual load capacity of the operated bridges in the classes of the standard load of the AK, there is a contradiction between the various existing load standards
   For a unified interpretation of the carrying capacity of bridges, both new and previously built according to various standards, it is necessary in all cases to follow the modern requirements fixed in the current GOST R 32960–2014. This provision requires testing at the regulatory level. When determining the possibility of passing a heavy vehicle over a bridge structure, there are situations when the pass condition determined by theoretical methods is not met, but the deficit in the lifting capacity of the superstructure is relatively small. In such cases, static tests of the structure are performed, the results of which determine the criteria for assessing the load capacity of the superstructure, regulated in the norms. Consideration of the effect of the coating thickness on the bridge load capacity should be justified by the test results.
   At the same time, the values of the reliability coefficients to the loads from the layers of clothing of the riding cloth, taking into account the unevenness of the thickness of the layers and the measurement error, must be determined separately by statistical methods with the security accepted for the calculated values – “three standards”. To take into account the possible increase in the thickness of the asphalt concrete coating during the operation of the bridge, it is advisable to introduce an additional coefficient of a prospective increase of 1.1 to the load from the coating, or alternatively, increase the measured thickness of the asphalt concrete coating by 4–5 cm.

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