| Abstrakt: |
A numerical model to simulate loading process of prestressed concrete (PC) continuous beams and slabs at elevated temperature is presented. It is considered that plane sections before bending remain plane after bending. Based on the thermal-mechanical coupling constitutive models of concrete, reinforcing and prestressing steels, the transient strain, creep strain in concrete at time t + 1 could be calculated by the stress in concrete at the former step. The coupled constitutive model of concrete could be decoupled, and the reinforcing and prestressing steels were calculated by the same way. Therefore, the moment-curvature relationships of PC beams and slabs subjected to fire can be calculated. The moment of flexure, deflection and support displacement of the beams and slabs imposed by curvature and support reaction together was calculated respectively. The support reaction was calculated by the iteration method until the deflection compatibility equation at the support was satisfied, and the deflection of continuous beams and slabs could be obtained. The deflection of PC continuous beams and slabs subjected to fire calculated by the computer program is verified by correlative fire resistance experiments. Through these studies, it is shown that support and span restraint effect has significant influence on the fire resistance of PC continuous beams and slabs. The mid-span deflection in side spans is larger than that in inner spans. [ABSTRACT FROM AUTHOR] |
