Abstract:4 batches of self-stressing concrete with different mixture proportions and 11 self-stressing concrete filled steel tubes were continuously monitored.Effect of various conditions on the structural self-stress is discussed.Strain characteristics of different expansion factors(such as free expansion,confined expansion and effective expansion,etc) and the influential factors are analyzed.It is shown that some factors((e.g.) steel ratio,section dimension,aspact ratio,mix proportions of concrete etc.) have a significant effect on self-stress and expansion.It can also be drawn that the same factor has different effect on various expansions.