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基于陕西省某连续刚构桥实桥监测系统采集到的桥梁有效竖向预应力长期变化数据,以实测数据作为初始序建立灰色系统理论预测模型GM(1,1),分析竖向预应力损失随时间的变化规律,进行时间非等步距残差修正,提出竖向预应力长期损失预测模型.采用该模型预测竖向预应力长期损失占控制张拉力的比例为7.92%,与实桥监测的7.8%~8.2%基本吻合,表明若采用公路桥规设计张拉力的0.6倍作为竖向预应力施工控制标准,将导致桥梁后期有效竖向预应力达不到要求.建议施工过程中锚下应力控制应充分考虑长期损失效应影响,压浆前锚下有效应力不小于设计张拉力0.7倍为宜.这为竖向预应力施工及无损检测提供了理论依据和参考,对PC混凝土箱梁竖向预应力体系应用发展具有重要的理论意义及实用价值.
Based on the long-term effective vertical prestressing data collected from a continuous rigid frame bridge in Shaanxi Province, a gray system theory prediction model GM (1,1) is established based on the measured data. The vertical prestress loss With the variation of time, the long-term loss of vertical prestressing model was proposed, and the long-term loss of vertical prestressed model was predicted by using this model.The ratio of long-term loss of vertical prestressed to that of control tension was 7.92% Of 7.8% ~ 8.2% basically consistent, indicating that if the use of highway bridge gauge design tensile 0.6 times as the vertical control of prestressed construction standards, will lead to an effective late vertical bridge pre-stress less than the requirements of the proposed construction of the anchor Stress control should take full account of the long-term loss effect, the effective stress before anchor grouting is not less than 0.7 times the design tension is appropriate.This provides theoretical basis and reference for vertical prestressed construction and non-destructive testing of PC concrete box girder vertical The application of prestressed system development has important theoretical significance and practical value.