Despite the awareness about the hazard gained through the past evidence, fire following an earthquake remains a predominant agent of damage to buildings and life-line structures. Often the damage caused by the subsequent fire can be more severe than the damage caused by the ground motion itself. Concrete filled double skin tube (CFDST) columns as a special composite structure are particularly prone to the inadequate steel-concrete interface bonding and subsequent local buckling during separate fire conditions and seismic action. To establish a favorable interface interaction between steel and concrete as well as to postpone overall buckling under post-earthquake fire, the effectiveness of stiffening CFDST columns with longitudinal steel stiffeners are investigated. The analyses on CFDST columns with different patterns of stiffeners embedded in the interior or exterior surfaces of the inner or outer tubes are conducted with a sequentially coupled approach, starting with a heat transfer analysis and followed by a stress/deformation solution. In the finite element modeling, the confinement provided by both the inner and outer tubes on the compressive strength of concrete is accounted for. The effect of concrete fracture is incorporated by inserting a horizontal discrete crack model at the location of the major tensile crack. The results showed that stiffeners on the exterior surface of the inner tubes are among the most effective of various patterns studied in enhancing the fire endurance of the columns up to 64%. For stiffened CFDST columns contrary to the unstiffened ones, the fire-resistance reduction to seismic damage is usually less than 5% of the initial value. The fire-resistance rating reduction obtained for hollow ratios of 0.5 is 58%, with respect to the hollow ratio of 0.25.

尽管已经意识到通过过去的证据获得的危害，但是地震后的火灾仍然是破坏建筑物和生命线结构的主要因素。通常，随后发生的火灾造成的损坏可能比地面运动本身造成的损坏更为严重。填充混凝土的双层皮管（CFDST）柱是一种特殊的复合结构，特别容易发生钢-混凝土界面粘结不足以及随后在单独的火灾条件和地震作用下发生局部屈曲的情况。为了建立钢与混凝土之间的良好界面相互作用以及推迟地震后大火的整体屈曲，研究了使用纵向钢加强筋来加固CFDST柱的有效性。对CFDST柱的分析是通过顺序耦合的方法进行的，其中CFDST柱的内，外管的内表面或外表面中嵌有不同的加强筋，从传热分析开始，然后进行应力/变形解决方案。在有限元建模中，考虑了内管和外管对混凝土抗压强度的限制。通过在主要拉伸裂缝的位置插入水平离散裂缝模型来合并混凝土裂缝的影响。结果表明，在内管外表面上的加强筋是研究的各种模式中最有效的一种，可将圆柱的耐火性提高多达64％。对于与未加筋相反的加筋CFDST柱，抗火破坏性的降低通常小于初始值的5％。空心率为0.5时，相对于空心率为0.25，耐火等级降低为58％。