In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, doe...In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position, which can be used for verification of steel-concrete interaction in real bridge structures rather than in specimens is proposed. The range of the index value changes, obtained during load testing of a typical steel-concrete composite beam bridge, is presented. The investigation was carried out on a motorway viaduct, consisting of two parallel structures. During the testing values of strains in girders under static and quasi-static loads were measured. The readings from the gauges were used to determine the index, characterizing composite action of the girders. Results of bridge testing under movable load, changing position along the bridge span is presented and obtained in-situ influence functions of strains and index values are commented in the paper.展开更多
This study proposes a concept for the development of a fireproof design code for the verification of dwellings susceptible to wildfire action.There are currently structural codes for the design of buildings when subje...This study proposes a concept for the development of a fireproof design code for the verification of dwellings susceptible to wildfire action.There are currently structural codes for the design of buildings when subjected to indoor fires,outside fires that grow on the facade of buildings,and even fires in an accident situation due to ignitions with hydrocarbons or transportation vehicles.All of these security verification specifications are described in EC1:1-2.The current regulation in Portugal uses safety criteria and risk categories that are for indoor fires,therefore is very conservative and may not present an economic fireproof design against the action of wildfires.The aim of this work is a straight verification based on natural temperature characteristic curves that simulate wildfire heat flow by convection,radiation,and the deposits of firebrands.展开更多
文摘In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position, which can be used for verification of steel-concrete interaction in real bridge structures rather than in specimens is proposed. The range of the index value changes, obtained during load testing of a typical steel-concrete composite beam bridge, is presented. The investigation was carried out on a motorway viaduct, consisting of two parallel structures. During the testing values of strains in girders under static and quasi-static loads were measured. The readings from the gauges were used to determine the index, characterizing composite action of the girders. Results of bridge testing under movable load, changing position along the bridge span is presented and obtained in-situ influence functions of strains and index values are commented in the paper.
文摘This study proposes a concept for the development of a fireproof design code for the verification of dwellings susceptible to wildfire action.There are currently structural codes for the design of buildings when subjected to indoor fires,outside fires that grow on the facade of buildings,and even fires in an accident situation due to ignitions with hydrocarbons or transportation vehicles.All of these security verification specifications are described in EC1:1-2.The current regulation in Portugal uses safety criteria and risk categories that are for indoor fires,therefore is very conservative and may not present an economic fireproof design against the action of wildfires.The aim of this work is a straight verification based on natural temperature characteristic curves that simulate wildfire heat flow by convection,radiation,and the deposits of firebrands.
