ISO 28841:2013 pdf free

ISO 28841:2013 pdf free.Guidelines for simplified seismic assessment and rehabilitation of concrete buildings
Shear cracks are those that result from tension stresses corresponding to applied shear forces. The cracks run diagonally, typically at an angle of 359 to 709 from the horizontal. The angle of cracking depends on normal forces (e.g., axial load) and on the geometry of the component. For components that have undergone cyclic earthquake displacements of similar magnitude in both directions, the cracks cross each other, forming X patterns. Flexural cracks often join up with diagonal shear cracks. A typical case is in a wall pier where a horizontal crack at the wall boundary curves downward to become a diagonal shear crack as it approaches the pier centerline. When shear cracks connect to flexural cracks, determine the widths of the flexural portion of the crack and the shear portion of the crack separately. Cracks initially form perpendicular to the direction of the principal tension stresses in a section. At any point of a component, it is possible to relate the orientation of initial cracking to the applied stresses by considering the stress relationships represented by Mohr’s Circle.However, after initial cracking, the orientation of principal stresses will change and crack patterns and stress orientations are affected by the reinforcement.
In investigating reinforced concrete components, the designer should establish whether critical flexural and shear cracks extend through the thickness of the element. It is assumed that the most significant flexural and shear cracks are full-thickness cracks having a similar crack width on each side of the element. L .aboratory tests have invariably used in-plane loading. Therefore, significant cracks observed in these studies are typically full-thickness. In actual buildings, out-of plane forces and deformations may cause cracks to be partial-thickness, or they may result in cracks that remain open to a measurable width on one face of the element, but are completely closed on the opposite face. In such cases, the designer should use judgment in assessing the consequences of the critical cracks. It may be justified to use the average of the measured crack width on each face. More conservatively, the maximum crack width on either face of the element can be used in classifying the observed damage.ISO 28841 pdf free.