Actual stress state of the superstructure of the driveway overpass over gateways on hydraulic structures of the Dnieper hydroelectric power station with carriageway orthotropic deck plates

Abstract

The paper highlights peculiarities of analysis and operation under the actual technical condition of bridge superstructures with the orthotropic deck plates of the driveway. As an example, the design of the superstructure of the existing driveway along the overpass over gateways of the hydraulic structures of the Dnieper Hydroelectric Power Station is considered. The description of existing structures of the overpass over gateways is presented. It is noted that the erection joints of the driveway orthotropic deck plate are taken according to the inventor's certificate No. 431279 at the request of State Design Institute Ukrproektstalkonstruktsiya (now Limited Liability Company «V. Shimanovsky Ukrainian Institute of Steel Construction»). The methodology to build-up the finite-element model of the overpass over gateways is described, which allows to display adequately the actual technical condition of the overpass taking into account the data of the performed survey. Uneven distribution of normal stresses in the orthotropic plate decking is studied under the action of permanent load (dead load of its structural elements) and imposed load (wheeled vehicle load of a convoy of cars weighing 30 tf each (H-30) and uniformly distributed design load from human crowd on the sidewalk). Reduction factors characterizing the uneven distribution of normal stresses are found by calculating the computational model using the engineering-and-analytical (normative) method and the numerical calculation method. The results of the numerical calculation method in the form of vertical displacements and normal stresses in the decking of the orthotropic plate and tangent stresses in the webs of the main girder are presented and analyzed. The obtained results are compared. It is noted that the defects and damage of the driveway superstructure along the overpass over gateways affect the parameters of the stress-strain state of bridge structures in the range from 7 % to 10,5 % for nearly all structural elements as a result of almost uniform long-term corrosion with a minor weakening of the cross sections except for the area about 0,5–0,7 m wide, which is adjacent to the sidewalk and extends on the entire length of the overpass over gateways; unlike all other elements of the driveway superstructure, there is largely uneven corrosion of the metal of structural elements on it, so in this area the difference between displacements and stresses of the design state and actual state increases by about 1,5–2 times and reaches from 16 % to 20 %. Conclusions and recommendations based on the research results are formulated.