CAJ | 학술논문

为明确火灾下混凝土桥梁预应力的衰变幅值与高温之间的变化关系，采用热力耦合计算方法，基于强度损失的虚拟层截面等效原理，设定火灾下混凝土箱梁预应力火灾高温分析工况，研究单面火灾和三面火灾模式下混凝土箱梁的截面温度场分布状况，计算不同延火时间混凝土箱梁预应力沿程(沿桥梁跨径)分布状态，揭示强度减损下混凝土箱梁预应力火灾高温沿程损失规律.研究结果表明：箱梁底板受火，温度大致呈水平层状分布；箱梁底板和两侧腹板受火，温度呈U形分布，并且多面受火时的温度峰值大于单面受火时的温度峰值；随着延火时间的增加，高温层逐渐向内扩展并且扩展宽度递增；延火全程中，相对处于腹板上部，处于腹板下部的钢束预应力沿程损失较大，四分点的预应力损失值较其他部位大，大约是其他部位的1．1倍；跨中的预应力损失增长幅度相对较大，增长幅度最大值约为9．4％；锚下预应力损失值最小；整个延火过程中，沿程预应力损失呈倒 W形.
위명학화재하혼응토교량예응력적쇠변폭치여고온지간적변화관계，채용열력우합계산방법，기우강도손실적허의층절면등효원리，설정화재하혼응토상량예응력화재고온분석공황，연구단면화재화삼면화재모식하혼응토상량적절면온도장분포상황，계산불동연화시간혼응토상량예응력연정(연교량과경)분포상태，게시강도감손하혼응토상량예응력화재고온연정손실규률.연구결과표명：상량저판수화，온도대치정수평층상분포；상량저판화량측복판수화，온도정U형분포，병차다면수화시적온도봉치대우단면수화시적온도봉치；수착연화시간적증가，고온층축점향내확전병차확전관도체증；연화전정중，상대처우복판상부，처우복판하부적강속예응력연정손실교대，사분점적예응력손실치교기타부위대，대약시기타부위적1．1배；과중적예응력손실증장폭도상대교대，증장폭도최대치약위9．4％；묘하예응력손실치최소；정개연화과정중，연정예응력손실정도 W형.
To study the variation relations between the prestress decay amplitude of concrete bridges and high temperature,based on the virtualization equivalence principle of the concrete strength loss,fire condi-tions were designed to analyze the temperature field of concrete bridge with box girder under single-side fire and three-side fire,and the thermo-mechanics coupled method was adopted to calculate the prestress distribution along the bridge span of concrete bridges with box girder at various fire time and disclose pre-stress loss law of concrete bridges with box girder exposed to high temperature based on strength deroga-tion of concrete.The results show that:the temperature generally presents a layered distribution when the floor of concrete bridge with box girder is exposed to fire.When the floor and both sides of the web of con-crete bridges with box girder are exposed to fire,the temperature generally presents an U-type distribu-tion,and the temperature peak value at intersection is higher than that of in other parts.With the increase of the fire time,high temperature layer gradually extends inward and distribution width expands.Prestress loss of steel strand located at the bottom of the web is relatively more than it located in the upper position of the web,prestress loss at the quarter of span is more than that of other parts and its value is about 1 .1 times than that of other parts.The increase amplitude of prestress loss at mid span is more than that of other parts,and the maximum growth rate is about 9 .4%.Prestress loss loacated in anchor has a minimum value,and prestress loss along span presents an inverse W-type during various time steps.The research can provide a guideline for fire-resistant design and assessment of prestressed concerte bridge after fire hazard.