Reinforced concrete buildings and structures when being exposed to fire, the concrete qualities can vary in the case of an uncontrolled fire. It is essential to know how concrete's properties maybe change as a result of exposure to high temperatures and loading for normal concrete with / without fibers reinforcement. To understand the strength characteristics of concrete structures exposed to high temperatures is important. In order to predict how these structures will perform after exposure to this condition. Therefore, this study focuses on the investigation of the combined impact of loading and high temperature on the properties of concrete samples by testing the compressive strength, flexural strength, ultrasonic pulse velocity test (UPV) and rebound number of normal strength concrete (NSC) with/without steel fiber or basalt fiber. Two types of fibers were used in this study, steel and basalt fibers. The type of steel fiber employed in this investigation is hooked end steel fiber with 1% volume fraction of concrete while the type of basalt fiber is chopped fiber with 1% volume fraction. The concrete samples were subjected to three sustained load cases (20, 40, and 60) % of ultimate load and exposed to elevated temperatures (300 and 500) °C for about 2 hours. In addition, using unrestrictive test before and after loading and after heating. The results indicated that the loss in compressive strength is little where the percentage of reduction of compressive strength at 300° C was observed between (6-16%), (6-10%) and (16-19%). While, at 500° C temperature, the percentage of deterioration in compressive strength ranged (14-36%), (22-23%) and (17-22%) for mixes (NSC, Normal strength concrete with steel fiber (SF1) and normal strength concrete with basalt fiber (BF1)) respectively for all load cases. At 300° C temperature, the percentage of reduction of flexural strength between (14-18%), (6-9%) and (20-46%), while at 500 °C temperature, the percentage of reduction of flexural strength between (30-36%), (23-27%) and (35-76%) for mixes (NSC, SF1 and BF1) respectively for all load cases. The results also indicated that cubes show no significant difference in ultrasonic pulse velocity for mixtures (NSC, SF1 and BF1) in all load cases at the 300 OC, whereas at 500 OC, NSC mix has a higher ultrasonic pulse velocity than SF1 and BF1 for (40% and 60%) of load. In addition, it was discovered that the percentage of rebound number reduction fell between (4-17%), (7-12%), and (4-7%) at 300 ° C, while at a temperature of 500° C, the percentage of rebound number reduction fell between (15-26%), (22-26%), and (14-18%) for mixes (NSC, SF1, and BF1), respectively. It was discovered that basalt fibers improved compressive strength at high temperatures and under all loading conditions, hence it is preferred to employ them in this field as opposed to improving flexural strength. In comparison with the use of other types of fibers, steel fiber performed well in flexural tests when it came to resisting loads and high temperatures.