It is common knowledge that structural fires have led to a great loss of buildings and damage to property in the past two decades. Therefore, there is a growing need to provide approaches for post-fire repair of structural members to enhance their structural safety. This paper presents a state-of-the-art review on the repair of fire-damaged reinforced concrete (RC) members with axial load. The investigations into the effects of loading method, physical dimension and bonding behavior on the residual strength of members are presented. In the meantime, the available experimental investigations on the performance of fire-damaged RC members with axial load repaired with concrete jacketing, steel jacketing and fiber-reinforced polymer (FRP) jacketing are summarized. Moreover, models for predicting the residual strength of fire- damaged columns are reviewed.

The mechanical properties of both concrete and steel reinforcement, and the load-bearing capacity of reinforced concrete (RC) structures are well known to be temperature-sensitive, as demonstrated by the severe damage that major fires cause in buildings, followed—in extreme cases—by their collapse. Since in most cases RC structures survive a fire, retrofitting fire-damaged RC members is a hot subject today. In this paper, after a recall on the performance of RC beams and slabs in fire, different repair techniques are considered, among them externally bonded reinforcement, near surface-mounted fiber-reinforced polymers (FRP), bolted side plating, jacketing with high- and ultra-high performance concretes or mortars, and damaged-concrete replacement. Last but not least, the design equations aimed at evaluating the residual load-bearing capacity after repairing are also presented and discussed.

Compared with traditional timber boards, timber–concrete composite (TCC) boards demonstrate a higher rigidity and bearing capacity, improved vibration, and better behavior under seismic conditions. However, they become charred when exposed to fire due the combustibility of timber, and the fire safety of this material is considered essential. In this research, 60 min fire exposure tests and residual load-carrying capacity tests following fire exposure were carried out on three full-scale composite boards, two of which were covered with an innovative form of gypsum board protection. The effect of the innovative protection on the temperature field and fire resistance of the TCC boards was studied in detail. The test results indicate that the fire resistance of the TCC boards was effectively improved by using the innovative protection. If the coverage ratio is identical, a wider single gypsum board can demonstrate a slight increase in residual carrying capacity. Finite element models of TCC boards were established to investigate the temperature field during fire exposure and the residual load-carrying capacity of the TCC boards after fire exposure, demonstrating high applicability and accuracy. The conclusions in this paper can provide reference for fire design in engineering.