What is shear lag and when must it be considered?

What is shear lag and when must it be considered?

Shear lag is a concept used to account for uneven stress distribution in connected members where some but not all of their elements (flange, web, leg, etc.) are connected. The reduction coefficient, U, is applied to the net area, An, of bolted members and to the gross area, Ag, of welded members.

What is shear lag how it can be reduced?

It is found that bracing system considerably reduces the shear lag effect and hence increases the building stiffness to withstand lateral loads. Different geometric patterns of bracing system are considered. The best effective geometric configuration of bracing system is concluded in this study.

Why is shear lag important?

Shear lagging, resulting from non-uniformity of stress distribution around the connection, is one of the most important design considerations in steel construction since it reduces the load capacity of tension members.

What is shear lag width?

Solution: The length of outstanding leg will be w = 75 mm and w1 = 40 mm. So the shear lag width, bs = w + w1 – t = 75 + 40 – 10 = 105 mm.

What is the effect of shear lag?

This phenomenon is known as “shear lag.” The effect of shear lag is almost always to reduce the stress in a stringer below that given by the beam formula, s = My/I. Due to shear lag, the employment of longitudinal stiffeners may result in a lowered weight-strength efficiency.

What is lug angle?

Lug angle is small piece of angle used to connect outstand legs of the members to the gusset plate. • The purpose of lug angle is to reduce the length of connection to the gusset plate and to reduce shear lag effect.

What is block shear failure?

Block shear failure is a limit state that combines tension failure on one plane and shear failure on a perpendicular plane (Fig. 1). The guidelines assume that, when one plane reaches ultimate strength, the other plane develops full yield.

How do you calculate shear lag?

The common equation given in AISC [1] specification to calculate the shear lag factor of tension members is as follows: where U is the shear lag coefficient, which is equal to unity for a connection that ensures uniform stress distribution over the section; is the distance from the shear plane to the center of gravity …

What are a lug angle and its sketches?

The purpose of lug angle is to reduce the length of connection to. the gusset plate and to reduce shear lag effect.• If lug angle is used then the. unconnected length of main angle behave like a connected leg and entire cross. section• area of the angle become effective in resisting tension. So if lug angle is.

What are examples of shear stress?

Shear stress occurs whenever there is contact between two materials or components. Examples include stress exerted on a set of cantilever beams (with or without adhesion between layers), horizontal beams used in construction, pipelines carrying flowing fluids, soil when it is subjected to loads from…

What are effects of shear?

High shear rates lead to reduced apparent viscosity for some fluids. Lower viscosity results in lower pressure drop during fluid transport. Conversely, other fluids become more resistant to flow with increased viscosity at increased shear rates. High shear rates can also cause breakdown of the fluid structures, which leads to reduced viscosity.

What is shear stress and shear strain?

Shear stress and shear strain are also defined in the same way. Let’s see How we can define them? When a body is subjected to two equal and opposite forces acting tangentially, across the resisting section, then the body tends to shear off the section. The stress induced in the section is known as the shear stress.

What is shear distibution?

During flow a shear stress distribution develops in the cavity, with the shear stress at the freezing skin layer near the wall at a maximum value, retreating to a minimum value in the hot flowing center.5 The critical shear stress represents the value above which primary bonds in the polymer backbone can be broken during flow.