Mechanical characteristics of concrete subjected to multi-axial stresses are considerably different from those under uniaxial stress in terms of the strength and the deformation as well. It is necessary to grasp these characteristics for analysis and design of reinforced concrete structures or their members under multi-axial stresses. In this paper the recent trends of studies on the strength, deformation and failure criterion are reivewed. The mechanical models of concrete under multi-axial stresses have been proposed by many researchers working in the finite element analyses of reinforced concrete structures. Here comparison and discussion are made on the representative studies about modeling of stress-strain relationships, yielding and failure criterions, cracking, aggregate interlock and compressive failure.
In Japan, the slipform is not so common construction method as in Europe. Since about 20 years before the slipform has been often used for the construction of the silos and the chimneys. In 1978 the micro wave tower with square concrete core and the inclined wall was built in Ishizaki for the construction of the flexible slipform system was applied. This report show the outline of the design and the tower construction using the system developed by Shimizu Construction Company.