超低温下钢筋混凝土梁受弯性能试验研究

Experimental research on flexural properties of reinforced concrete beams at cryogenic temperatures

为确保钢筋混凝土结构在超低温下的安全使用,借助超低温冷库降温和自制保温箱保温的方式,对分别受20、-40、-70、-100℃等温度作用的不同配筋率的12根钢筋混凝土梁的受弯性能进行了试验研究。结果表明:随着温度的降低,钢筋混凝土梁的开裂荷载逐渐提高,裂缝数量减少,而裂缝间距增大;在同一荷载下,钢筋混凝土梁的挠度及钢筋应变均随温度的降低而呈减小趋势;随着温度的降低,钢筋混凝土梁的屈服荷载与极限荷载都有一定的提高,配筋率越大提高程度越大,且屈服荷载的提高程度较极限荷载的提高程度更大;在低温条件下,梁的平截面假定依旧成立,梁的延性降低;考虑材料参数的温度效应后,利用规范的承载能力计算公式估算的构件的受弯承载力仍然可靠,但在低温条件下梁的刚度变化较大,规范的挠度计算公式具有一定的参考意义。

In order to promote the safe application of reinforced concrete structure at cryogenic temperatures,experiments on flexural properties of 12 reinforced concrete beams with different reinforcement ratios at 20℃,-40℃,-70℃,-100℃ were carried out,with the help of cryogenic cold storage cooling temperatures and homemade incubator keeping temperatures. The results show that,the cracking load of reinforced concrete beams gradually increases as temperature decreases,the number of cracks reduces when the crack spacing increases; under the same load,the deflection of reinforced concrete beams and reinforcing bar strain decrease gradually with dropping temperature; the yield load and ultimate load have a certain improvement with the increase of reinforcement ratio,and the yield load always increases more; the plane-section assumption is still valid at low temperatures,and the ductility of beams is reduced; considering the temperature effect on material parameters,the ultimate load formulas are still applicable; since the stiffness of beams changes obviously at low temperatures,the deflection formula has some reference value.