膨胀剂掺量和含钢率对钢管混凝土徐变性能的影响

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发布时间：2022-04-08

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：对膨胀剂掺量(质量分数 )为 4 ，8 和 12 的 3种钢管混凝土 (CFST，concrete filled steel
tube)在含钢率 (面积分数，钢管与混凝土的截面面积比)为 3．8 ，4．1％，6．6 ，9．2 和 1O．8 的
5种情况下进行了徐变性能试验．结果表明：膨胀剂掺量为 4 时钢管混凝土徐变度最大，掺量为
8 时徐变度次之，掺量为 12％时徐变度最小；膨胀剂掺量 12 相比膨胀剂掺量 8 时的钢管混凝
土徐变度下降并不显著；含钢率的增加有效分担了钢管混凝土的外部荷栽，使其徐变度有所减小．
应用扫描电镜 (SEM)观测及能谱仪 (EDS)分析得出膨胀剂的作用机理：膨胀剂反应生成钙矾石，
一方面通过钙矾石的微膨胀补偿了收缩；另一方面钙矾石填充在结构孔隙中，使水泥石更加密实．
分析合钢率对钢管混凝土徐变性能的影响机理后认为混凝土应力随着含钢率的增加而减小，原因
是含钢率的增加使得钢管对混凝土的约束也有所增加，由此限制了混凝土的变形．
关键词：钢管混凝土；膨胀剂；含钢率；徐变；机理
中图分类号：TU398 文献标志码：A doi：10．3969／j．issn．1007-9629．2015．05．006
Effects of Expanding Agent Content and Steel Ratio on
Creep Characteristics of Concrete Filled Steel Tube
ZHANG Rongling ， WANG Qicai ， MA Lina ， LONG Guangcheng。， GE Yong ， YANG Yang
(1．School of Civil Engineering。Lanzhou Jiaotong University，Lanzhou 730070，China；
2．School of Civil Engineering，Central South University，Changsha 410075，China)
Abstract：Experiments with expanding agent proportion(by mass)of 4 ，8 and 1 2 were carried out re—
spectively in order to clarify the effects of expanding agent proportion and steel ratio on concrete filled steel
tube(CFST)’S creep characteristics．The results show that 4 of expansive agent additive affects the creep
degree most，the 8 of expanding agent additive does less，and the 1 2 of expansive agent additive does the
least． w hen addition of expanding agent was decreased from 1 2 to 8 ，the creep degree of concrete filled
steel tube was slightly decreased．By means of SEM and EDS the action mechanism of expanding agent was
clarified． The analysis revealed that expanding agent reacts with concrete to produce ettringite． On the one
hand it may compensate shrinkage by slight expansion． On the other hand it m ay fill in pores and made dense
for hardened cement．The concrete filled steel tube with tube wall thickness of 3．8 ，4．1 ，6．6 0／／，9．2
and 1 0．8％ were prepared．It is shown that the exterior loads are shared with the increase of stee1 ratio．The
creep degree is decreased． The steel ratio affects CFST creep mechanism on the same loading condition． The
study concludes that the stress in concrete decreases along with increasing steel ratio．W ith the increase of wall
thickness，steel would be binding the concrete and limiting the deform ation of concrete．