tailieunhanh - BASICS OF CONCRETE SCIENCE - CHAPTER 5

DEFORMATIONS OF CONCRETE Phát sinh biến dạng của bê tông cứng, khai thác và thử nghiệm bê tông. Hai loại biến dạng của bê tông là: 1. Biến dạng do áp dụng tải trọng bên ngoài (biến dạng điện), 2. Biến dạng do khối lượng thay đổi theo ảnh hưởng của thay đổi nhiệt độ và độ ẩm (biến dạng riêng). | CHAPTER 5 DEFORMATIONS OF CONCRETE L. Dvorkin and Deformations of concrete arise up at hardening exploitation and test of concrete. Two kinds of deformations of concrete are 1. Deformations due to applied external loads power deformations 2. Deformations due to volume changes under influencing of changes in temperature and moisture content own deformations . . Concrete deformations at short-term load Concrete Performance in constructions is determined by elastic and plastic deformations. Complete deformation of concrete at a definite age of hardening st is calculated by the equation st sel s pl Sshr where sel - elastic deformation 8pl - plastic deformation Sshr - deformation of shrinkage. 88 Fig. . The idealized chart of deformations in cement stone at the axial compression at rapid loading 8 - deformation Ơ - stress On the idealized chart of compression of cement stone it is possible to select three basic areas a-b- absence of cracks in the structure of cement stone b-c- appearance of microscopic cracks c-d- destruction of cement stone as a result of spontaneous formation of growing cracks. For description of cement stone and concrete deformation under loading a number of rheological models are offered. .