| 摘要 |
PURPOSE: A construction method of a multi-span continuous preflex composite bridge is provided to reduce tensile stress in lower flange concrete by reducing positive moment at a spot where rise and fall works are performed previously by using point rise and fall at two spots. CONSTITUTION: While preflex composite beams are connected over three spans at a regular interval, positive moment corresponding 25% of negative moment generated at a point C is generated at a point B due to rise of the point C. Then, tensile stress is generated in lower flange concrete of the point B where compressive stress is not applied. To offset the tensile stress, point raising force is applied to the point B before the rise of the point C. Thus, negative moment in accordance with the positive moment of the point B is generated in the point B. Therefore, the moment of the point B becomes zero and the lower flange concrete is prevented from tensile stress.
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