Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Feasibility of Utilizing High-Performance Lightweight Concrete in Pretensioned Bridge Girders and Panels
The use of high performance lightweight concrete in Texas prestressed concrete bridges has potential advantages and disadvantages. Advantages included reduced dead load, crane capacity, and shipping costs. Disadvantages include higher prestress losses, deflections, camber, and material costs. Prestressed concrete bridge girders can be designed with lightweight concrete that has compressive strengths of 6000 psi and 7500 psi and unit weights of 118 pcf to 122 pcf, respectively. Comparisons of AASHTO Type IV girders made from normal weight concrete and girders made from lightweight concrete, both with various composite concrete deck combinations, reveal that higher prestress losses and lower allowable stresses reduce the possibility of having fewer prestressing strands in the lightweight girder. The design of the lightweight concrete girder was controlled by the allowable stresses and not by ultimate capacity. The lower modulus of elasticity of lightweight concrete results in higher camber and deflections. Testing of 3/8-inch prestressing strands in precast concrete panels to determine the transfer length showed that the AASHTO provision of 50 times the strand diameter is conservative for these panels. The transfer length in the lightweight concrete panel was slightly higher than the transfer length in the normal weight concrete panels, but both were below the AASHTO criteria.
Feasibility of Utilizing High-Performance Lightweight Concrete in Pretensioned Bridge Girders and Panels
The use of high performance lightweight concrete in Texas prestressed concrete bridges has potential advantages and disadvantages. Advantages included reduced dead load, crane capacity, and shipping costs. Disadvantages include higher prestress losses, deflections, camber, and material costs. Prestressed concrete bridge girders can be designed with lightweight concrete that has compressive strengths of 6000 psi and 7500 psi and unit weights of 118 pcf to 122 pcf, respectively. Comparisons of AASHTO Type IV girders made from normal weight concrete and girders made from lightweight concrete, both with various composite concrete deck combinations, reveal that higher prestress losses and lower allowable stresses reduce the possibility of having fewer prestressing strands in the lightweight girder. The design of the lightweight concrete girder was controlled by the allowable stresses and not by ultimate capacity. The lower modulus of elasticity of lightweight concrete results in higher camber and deflections. Testing of 3/8-inch prestressing strands in precast concrete panels to determine the transfer length showed that the AASHTO provision of 50 times the strand diameter is conservative for these panels. The transfer length in the lightweight concrete panel was slightly higher than the transfer length in the normal weight concrete panels, but both were below the AASHTO criteria.
Feasibility of Utilizing High-Performance Lightweight Concrete in Pretensioned Bridge Girders and Panels
G. S. Sylva (Autor:in) / J. E. Breen (Autor:in) / N. H. Burns (Autor:in)
2003
80 pages
Report
Keine Angabe
Englisch
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