STEEL PIPE-CONCRETE COLUMNS WITH PRELIMINARY PRESSED CORE

摘要

Columns such as concrete in a pipe find wide application in construction of high-altitude buildings, underground and wide-span bridges in many countries of the world. The simple manufacturing techniques and essential economy of metal due to high bearing capacity make constructions of the steel pipes filled with concrete especially attractive. One of the basic defects of columns such as 《 concrete in a pipe is that the internal core and a steel holder do not work effectively, because of a difference in factors of Poisson of concrete and steel at small longitudinal compressing loadings. The effect can be achieved in use of the concrete, hardening under influence of pressure in such columns. Owing to a preliminary pressure of a steel pipe the concrete is in conditions of three-axial compression even at a low level of loading by axial compressing force. For experimental acknowledgement of efficiency of columns laboratory samples both round, and square sections have been made. The results of their tests for the central compression have shown that processing, of concrete mix by mechanical pressure of 2 … 4 Mpa results in increases in durability of initial concrete in such elements in 1.5-1.8 times. In addition, durability grows in 1.4-1.6 times due to three-axial compression of concrete. It positively affects the bearing capacity of pipe-concrete elements. The author develops the method of calculation of columns of the offered construction, taking into account features of work revealed during experimental research.