Abstract: Abstract: This paper focuses on steel connections using “rotating angle connecting module” in prefabricated modular structures. Fire resistance tests were carried out to study the fire performance of the steel connections with two different fire protection methods. The deformation curves, failure modes and fire resistance of the connections were studied. The National Standard GB/T 9978.1-2008 was applied to carry out the tests. Test results show: 1) for specimen A of which the columns were protected with 3-layers of high-performance gypsum boards (15+20+20) mm and the beams were protected with 2-layers of high-performance gypsum boards (20+20)mm, the fire resistance rating was more than 193 min. The gypsum boards remained a relatively good integrity, but a few gypsum boards in the middle of specimen fell off. The temperature at the steel column corners were higher due to the 2-diretional heat transfer. The temperature of connection was lower than that of steel columns and beams, due to the fact that the connection has thicker steel than columns and beams. The temperature of beams were higher than that of columns because beams had larger section factor. From the axil displacement of columns it could be sawn that the specimen stayed in its thermal expansion stage and the criteria of fire resistance rating were not met yet. 2) for specimen B of which the columns and beams were protected with 2-layers of fiber-reinforced calcium silicate boards and 60 mm-thick rock wool（120 kg/m3）, the specimen was elongated as the steel temperature raised up, and the gaps between gypsum boards expanded, but the boards remained integrity; the specimen started to reveal compression deformation at 131 min, and the test was stopped to prevent any damage to the furnace. It was shown that specimen B has similar temperature profiles as specimen A, but there was divergence among the temperature profiles because deformed steel stud at high temperature caused large gaps between gypsum board, and hot gases might reach the specimen through gaps and result in deferent temperature profiles at different spots. From the axil displacement of columns it could be sawn that the column stopped thermal expansion and stared to crush. Therefore, the specimen started to buckle, and it reached its failure stage and would fail soon. After the test, local buckling was observed on the column. Based on the results, specimen B was very closed to its failure at the end of the test. 3) the temperature curves showed a plateau at about 100 ℃ for both specimens, and this is because the moisture in the specimens evaporated and absorbed a large amount of heat. 4) for specimen B, the gypsum boards remained integrity, but the gaps between gypsum boards expanded a lot due to the deformation of steel studs at high temperature. Therefore, the stability of steel studs at high temperature is very important if they are used for supporting gypsum boards. 5) Test results show that the connection protected with 3-layers of high-performance gypsum boards (with thickness of (15+20+20) mm) has a fire-resistance rating of 3.00 h, while the connection protected with 2-layers of fiber-reinforced calcium silicate boards and 60 mm-thick rock wool has a fire-resistance rating of 2.00 h.

Key words: Key words: prefabricated modular building, steel structure;connection node, fire resistance, fire protection