THE VALUES’ DETERMINATION OF THE OSCILLATIONS’ INTRINSIC PERIOD OF THE RUBBER-METAL SUPPORTED SPAN STRUCTURE BY APPROXIMATE METHODS

Abstract

The natural vibration frequencies’ calculation of the pedestrian bridges’ span structures is still practically valued. Such factors as dynamic effects, elements’ structural features, the neglection of which is the norm in the classical hinge-rod model of the span structure, provide a significant influence on the dynamic characteristics of the longitudinal girders. Not taking into account the real conditions of the span structure supporting leads to the appearance in them of the vertical oscillations’ period in an unacceptable interval of 0.45 ... 0.60 s (in accordance with SP35.13330.2011). The appropriate preliminary calculations in engineering practice are based on approximate methods. However, the existing methods for determining the values of the oscillations’ intrinsic period of the span structures, which are based on the simplifications and the assumptions, have the significant calculation error. The research suggests the approximate method for determining the values of the intrinsic oscillations’ period of the span supported structures with the rubber-metal support parts. The proposed method is based on the work [1], the calculation scheme is also defined, the most accurate analytical expressions are also obtained on the differential equation solution basis. The longitudinal beams of the flyover along the M-60 «Ussuri» highway, in Khabarovsk-Vladivostok section 747- 750 km of the PK 156 + 132 are calculated as an example in the research.

Keywords

• pedestrian overpass
• vertical vibrations
• longitudinal and transverse bending
• beam deflection
• circular cleanliness
• rubber-metal support part