摘要
利用形状记忆合金(shape memory alloy,SMA)丝超弹性和激励回复产生较大驱动力的特性,将不同预拉长度及根数的Ni-Ti SMA丝预埋入混凝土模型梁中,研究了混凝土梁加载过程中Ni-Ti SMA丝电阻变化率与混凝土梁裂缝宽度的关系以及Ni-Ti SMA通电激励过程中混凝土梁裂缝恢复的变化规律.试验中考虑了SMA滑移的影响,并通过理论计算对其进行验证,计算时考虑了锚具造成的附加电阻的影响.结果表明:SMA显著提高了混凝土梁的变形能力和抗裂能力;在通电激励后,混凝土梁在Ni-Ti SMA激励回复效应驱动下,挠度迅速恢复,裂缝闭合;增加Ni-TiSMA总截面面积可提高合金对混凝土梁的驱动效果;在裂缝宽度小于1.5 mm时,Ni-Ti SMA电阻变化率和混凝土梁的裂缝宽度呈明显的线性关系;钢筋塑性变形的存在,对混凝土模型梁的变形回复起阻碍作用.
Taken advantages of the characteristics of super-elasticity and restoring forces while the shape memory alloy（SMA） was excited,concrete model beams were established by embedding different pre-stretching length,different pieces of Ni-Ti SMA under martensitic state into the concrete tensile zone before the concrete casted under environmental temperature,the relationship between the resistance rate of SMA and the cracks width of beams was studied under loaded process.The impact of slip and bond between the concrete and SMA was taken into account by embedding the anchor at both ends of the beam to prevent the slip of the SMA,the influence of additional resistance coming from the anchor was taken into consideration in the process simulated.The result is in good agreement with the experimental result.It was shown that SMA increased the deformation capacity of the beam significantly,the crack closed almost completely and the deformation recovered suddenly after the SMA was excited by electrifying.The drive effect can be improved by growing in quantity of SMA.When Cracks width of beam was less than 1.5 mm,the relation between rate of change of alloy resistance and crack width of concrete beam is linear,however,the existence of residual deformation of rebar play a very negative role while recovering of the residual deformation.
出处
《建筑材料学报》
EI
CAS
CSCD
北大核心
2010年第2期237-242,共6页
Journal of Building Materials
基金
甘肃省科技支撑项目(0708GKCA002)
甘肃省自然科学基金暨中青年科技基金资助项目(3ZS062-B25-031)
