预应力混凝土箱梁“蒸养”裂纹的成因及预防措施

Genesis and Preventive Measures of Atmospheric Steam Curing Crack in Pre-Stressed Concrete Box Girder

京承高速滦河特大桥在预应力箱梁冬季"蒸养"过程中,因混凝土内外温差、梁体顶板与底板收缩不一致和养护时降温梯度过大等原因,产生裂纹,采用加强混凝土梁的养护管理、蒸汽养护时适当增加大梁内的抗裂钢筋和严格控制升降温梯度等措施,有效解决了该问题。

The crack appeared in Luan River Bridge of Beijing-Chengde expressway during atmospheric steam curing of pre-stressed concrete box girder in winter,which was caused by the temperature difference between concrete inside and outside,the inconsistent contraction of top and bottom of the box girder,too large temperature gradient in maintenance.This issue has been settled by strengthening maintenance management,properly increasing crack resistance steel bar in the girder when doing atmospheric steam curing and strictly controlling temperature gradient.