Shear lag what is

Third, based on the first two parts of the paper, recommended changes to the AISC specifications are presented. Samuel Easterling; Lisa Gonzalez Giroux.

JavaScript is disabled! View Cart. Quiz: has been added to your profile! View Profile. Your cart has been updated! The coupon code has been applied to your cart! The coupon code has been removed from your cart! This is the reason that the shear lag factor having a upper limit being greater than unity Hi there, I read your blogs on a regular basis.

Your humoristic style is witty, keep it up! I enjoyed this blog post. Really helpful down to the ground, happy to read such a useful post. I got a lot of information through it and I will surely keep it in my mind. Keep sharing. Your blog had very good knowledge and that gave huge instructions and that was really commendable ideas. Steel buildings Canada.

Hi Parishith Jayan, Found your blog while searching for a solution online, blog is interesting and your zeal to answer queries posted is commendable. My doubt is, can we use rod as bracing in tension for wind forces as per IS And if we use chapter 12, can we use rod for OMRF. Post a Comment. Shear Lag in Steel Structures. If we consider ourselves attending a design class in the undergraduate degree program, once the design philosophies are over, the first design lecture would be on "Design of Tension Members".

You can check any standard textbooks, once the author finished talking about introductions, prerequisites, design philosophies, the first actual design would be "Design of Tension Members".

In fact, if you check the codebooks, they too follow the same order. Attached the content page of IS to support my argument. It is the simplest design involving not so complicated loading conditions and very few limit-states that are easy to understand. Regarding the limit states for tension members, the tension member can fail due to.

Gross section yielding Rupture of Net section Kindly note, I have not listed the limit states for the failure of connections.

See, it is simple. Very few concepts and that is why it is placed first in the order. Before moving to the topic, would like to ask one more question.

What are the most widely used tension member sections? As a designer, say, I am about to design a tension bracing member, the first section that comes to my mind would-be "Angle Sections" Hoping, you too think of the same. When considering angle members, there is one important behavior or phenomenon which should be addressed or taken into account while determining its tensile capacity.

It is nothing but "Shear Lag", which is the main concentration for today's article. Elements receiving force by shear transfer lag behind the elements receiving it directly via rivets. This lagging creates an unequal distribution of stresses around the member connected side, which is called the shear lag effect; i. Thus, as the loading increases, the region near the bolts with higher stresses enters into the plastic zone and starts rupturing before the gross-section of the member reaches its ultimate capacity.

Out-of-plane eccentricity is the perpendicular distance from the face of the connected part to the centroid point of the section, and connection length is the distance between the two outmost bolts. This equation was then validated using more than 1, test data. Several studies previously investigated the shear lag factor effect on various steel members, especially angles and channels.

Kulak and Wu investigated various variables affecting shear lag on bolt-connected members. Nelson tested 18 single angle tension members with bolted connections to investigate the strain distribution and deformation of specimens at all stages up to failure. Kennedy and Sinclair tested single-angle, single bolted connections to investigate the influence of the edge distance and the end distance on net section efficiency.

March led a series of tests on single-angle members in tension and compression. The effect of plastic behavior was studied during ultimate loading of the sections. Yip and Cheng performed an experimental program consisting of 23 angle and channel specimens to study the shear lag effect. The connection length and cross-sectional geometry were the major studied parameters. Chung and Ip investigated the finite element modeling of bolted connections between cold-formed steel strips and hot-rolled steel plates under shear.

Orbison et al. Gupta and Gupta presented simple equations for predicting the load caring capacity of single and double angles in tension. Pan investigated the shear lag effect on bolted cold formed steel tension members.

Fifty-four channel sections with different dimensions were tested using bolted connections. Paula et al. Kulak and Grondin performed a statistical study on the evaluation of LRFD rules for block shear capacities in bolted connections with test results. It was stated that there were two equations to predict the block shear capacity but that the one including the shear ultimate strength in combination with the tensile yield strength seemed unlikely.

Examination of the test results on gusset plates revealed that tensile ductility is insufficient to permit shear fracture to occur. Gupta and Gupta conducted finite element analysis to evaluate the stress distribution in the angle at design loads predicted by previously developed equations on the basis of experimental results.

Epstein performed an experimental study on double-row, staggered, and unstaggered bolted connections of structural steel angles. Gaylord et al. The authors suggested that the effective net area of the tension member was a function of four factors: steel ductility, fabrication methods, connection efficiency, and shear lag effects.

Kouhi and Kortesmaa conducted a series of tests on double-shear bolted connections. Steel with yield strength of 90 ksi MPa was used. The bolts were arranged in two configurations: two in one line and four in two lines.

The bearing resistance and block shear resistance of the specimens were evaluated. The reviewed literature indicates the importance of shear lagging as a major design consideration in steel construction since it reduces the load capacity of tension members.

Accordingly, the main objective of this finite element analysis FEA -based study is to evaluate the rationality of the AISC provisions for calculating the shear lag factor U and to propose a new equation for a more reasonable calculation of U for any W and WT standard size.

Three different bolt sizes were evaluated for each model with different connection lengths, resulting in a total of models for W sections and models for WT-sections. For each section type, the influence of the bolt diameter, connection eccentricity, flange width, depth, flange area, and gross-sectional area were evaluated. Explicit analysis has a few advantages over standard analysis as it uses less computer storage and computational time, which is more dynamic for solving discontinuous processes.

This means that once the fracture strain was reached, the stress in the elements declines immediately to zero. The curve turned to the descending branch as more elements in the critical section fracture. A linear solid element with reduced integration C3D8R was used to create the FE models and converging was ensured by refining the mesh size. The final mesh size was selected to be 0. The typical models of the bolted W and WT specimens are shown in Figures 1 , 2 , respectively.

The leading edge of the gusset plate was restrained in all directions. A value of 0. The length of the bolt shank was selected as the sum of the thickness of the beam and the gusset plate, and the part of the bolt outside the nut was omitted.

The bolt shank, the nut, and the washer were created as a unity, thereby indicating that the interaction among these parts was not considered. Preload was applied on each bolt at the first step of loading to ensure tight contact snug-tight during testing.

Figure 1. Typical FE model of bolted. A W section and B WT section. A clearance of 0. Prior to loading, the bolts were made to contact with the bolt holes to eliminate any slip.

This approach was taken to prevent any undesired computational error that could occur when the bolt shank bore on the bolt hole.

Slip between the bolt shank and the bolt hole was also eliminated through pre-loading. A longitudinal uniform pressure tension was applied at the end of the member. The magnitude of the maximum applied load adopted depends on the ultimate load that can be carried by the section without connection. The period of loading is fixed for all sections at one step loading, which is 1-min 60 s long with linear increasing, starting with 0 kip at 0 s and increasing to the maximum at 60 s.

Figure 2 shows sample meshing and stress contours generated from the FEA. Two criteria were taken into consideration for computing the reduction in the ultimate tensile strength of a given cross section. The first criterion was by inspecting the ultimate tensile load carried by the section and calculating the area that was effective during the load transfer. Then, the amount of the reduction in the net area can be obtained and related to U. This process was done using Eqs 2 and 3.

The obtained results for U using this criterion were denoted as U p. The second criterion depends on the stress values and contours in each element in the member generated from the FEA and comprised of computing the effectiveness ratio in each element by dividing the stress value in the element by the yield stress.

Then, the weight averages for all elements were calculated and related to U. The obtained results for U using this criterion were denoted as U E. The simulated two sections were selected based on the authors experience as initial representative sections with three standard bolt diameters. Table 1 summarizes the FEA results of the two sections, which indicates that the influence of the bolt diameter is insignificant, since the difference in U among the three bolt sizes was less than 0.

Other W sections were not simulated since the results were insignificant. Also, it was consistent in the results that the performance of the WT section follows a similar trend to the W sections; i.