Diagonal tension

It is important to note material such as those plastics or wood that are weak in either tension or compression will also be basically weak in shear. For example, concrete is weak in shear because of its lack of strength in tension. Reinforced bars in the concrete are incorporated to prevent diagonal tension cracking and strengthen concrete beams. Similar action occurs with RPs using fiber filament structures. 

The shear loads, V, are based on the ultimate bending resistance, r, of the structural element. Shear resistance is provided to support the resulting shear stresses, v. This allows the element to reach its full dynamic flexural loacf carrying capacity and not fail prematurely, in shear, at small deflection. Two major shear stresses must be checked diagonal tension at a distance from the support, and direct shear at the support. 

Diagonal Tension. The allowable shear stress, v (psi), on a concrete section without shear reinforcement is ... 

The primary failure mechanisms encountered in reinforced concrete buildings arc flexure, diagonal tension, and direct shear. Of these three mechanisms,. flexure is preferred under blast loading because an extended plastic response is provider prior to failure. To assure a ductile response, sections are designed so that the flexural capacity is less than the capacity of non-ductile mechanisms. 

Shear and Diagonal Tension, Report of ACI-ASCE Committee 526, ACI Manual of Concrete Practice-Part 2, American Concrete Institute, Detroit, Mich., I968. (U)... 

The vertical shear, resulting from the upward reaction of the soil, produces diagonal tension stresses in the foundation. The critical section lies at a dis-... 

The unit stress (diagonal tension) resulting from this vertical shear load can be determined as ... 

Example 4. Check diagonal tension stresses in the foundation considered in Example 1. Figure... 

Safe unit stress in concrete due to vertical shear (diagonal tension) (Ibs./sq. in.). . Safe unit stress in concrete base due to... 

Calculate unit stress in concrete using the equation for fd shown under diagonal tension. 

In actual practice, the depth of the base in the examples given could be reduced, if desired. All of the stresses for diagonal tension, punching shear, bending (upward and downward), and bond in the reinforcement are well below the allowable values. 

For vessels that require pivot bolsters, the shipping saddles shall be adequately braced by diagonal tension/compression rods between the vessel and the saddle. The rods and clips attached to the vessel shell should be designed by the vessel fabricator to suit the specific requirements of the carrier. 

For walls with moderate to high axial stress (more than 30 % of the wall axial capacity), cracks start to initiate within the bricks themselves due to diagonal tension in the bricks exceeding the tensile strength of the bricks. These cracks are also often complemented by staggered step cracking in head and bed joints, especially with wet mortar constmction. 

In conclusion, the use of an FRP retrofitting system in the direction of diagonal tension forces in the joint at 45° assures the strong-column weak-beam concept. In addition, the damaged zone location can be controlled through the utilized FRP retrofitting system. 

K = dynamic load factor for flexure, peripheral shear, and diagonal tension. 

The ultimate shear stress as a measure of diagonal tension, is computed for type I sections from... 

This lies within the range 3.0 > tm/to >0.1, hence the response is satisfactory. Diagonal tension at a distance dfrom the support... 

More recently, Crisafulli and Carr (2007) proposed a new macromodel in order to represent, in a rational but simple way, the effect of masonry infill panels. The model is implemented as a four-node panel element which is connected to the frame at the beam-column joints. Internally, the panel element accounts separately for the compression and shear behavior of the masonry panel using two parallel struts and a shear spring in each direction. This configuration allows an adequate consideration of the lateral stiffness of the panel and of the strength of masonry panel, particularly when a shear failure along mortar joints or diagonal tension... 

---