滨州黄河大桥主梁边箱模型试验

滨州黄河大桥主桥是三塔预应力混凝土斜拉桥,主梁为预应力混凝土箱梁.为加强主梁受力的整体性,抵抗静载和动载产生的横向弯矩,横梁结构内设置了横向预应力钢束.进行标准梁段足尺模型试验,观测试验模型横向预应力钢束张拉后,主梁边箱测点的应变,以及模型表面混凝土裂缝的情况.采用空间有限单元法,建立主梁节段的计算模型,对主梁边箱在横向预应力作用下的受力特性进行分析.研究表明,在张拉横向预应力钢束以后,主梁边箱斜腹板中部会出现高拉应力区以及混凝土裂缝.可以采取在边箱上翼板内增设纵向预应力束、增设边箱斜腹板内纵向非预应力钢筋等技术措施来改善边箱斜腹板的受力情况,避免混凝土裂缝出现.

Experimental on side boxes model of Binzhou Yellow River Bridge

Binzhou Yellow River Bridge is a three-tower cable-stayed bridge with prestressed concrete girders.To ensure the integrity of the girder and resist transverse bending due to dead load and service load,powerful transverse prestressing tendons were disposed in the diaphragms.During the on-site experiment for full-scale segmental model of the girder,stress and cracks of the side-boxes were surveyed.Through mechanical analysis for segmental model of the girder by spatial finite element method(FEM),the mechanism of the two side-boxes of girder under transverse prestressing was obtained.It was showed that under the transverse tension,high stress concentration and even concrete cracks would appear on the oblique webs of the model.Improvement such as adding prestressed strands and reinforced bars is available to abate high stress concentration and avoid cracking of concrete.