Steel elements are often required to sustain tensile forces, these elements are referred to as tension members or tie. Example of tension members includes steel bracings in buildings, roof truss members, cables etc. The design of steel elements in tension is straightforward. This is because the behaviour of steel in tension is closely related to the stress-strain behaviour of a material subjected to uniaxial tensile forces.

In this post, the design of steel elements in tension using Eurocode 3 will be presented.

#### Designing for Tension to EC-3

Steel elements exclusively subjected to tensile forces are under a uniaxial stress state. This is defined in Clause 6.2.3(1) that a steel element subjected to tension must satisfy the following expression:

Where N_{Ed}= the design tensile force ; N_{t,Rd}=the design tension resistance.

##### Tension Members with Welded Connections

For sections without holes (welded connections), the design tension resistance N_{t,Rd} should be taken as the design plastic resistance of the cross-section N_{pl,Rd}.

Where: A is the gross cross-section area, f_{y} is the yield strength of steel and γ_{M0} is the partial factor of safety defined as 1.0 in the National Annexe.

##### Tension members Welded on one leg

Members that comprise angles connected by welding only in one leg can be treated as being concentrically loaded. Resistance can be determined using the expression given above but based on an effective cross-section area. According to Clause 4.13 of BS EN 1993-1-1, this is determined as:

- for angles of equal legs or unequal legs that are connected by the larger leg, the area of the effective section may be considered as equal to the gross area.
- for angles of unequal legs, connected by the smaller leg, the area of the effective section should be taken as equal to the gross area of an equivalent angle, with legs that are equal to the smaller of the legs

##### Tension Members with Bolted Connections

For section with holes (bolted connections), the design tension resistance is taken as the lesser of the following.

- The plastic resistance of the gross section as defined above; and
- The design ultimate resistance of the net cross-section at holes for fasteners which is defined as

Where: A_{net} = is the net _{u} is the ultimate strength of steel and γ_{M2} is the partial factor of

##### Tension Members Bolted on one leg

However, there are further requirements. Unsymmetrically connected members in tension such as angle iron connected by one leg, T or channel sections. The eccentricity in joints and the effects of the spacing and edge distances of the bolts must be taken into account in determining the design resistance.

Clause 3.10.3(2) of BS-EN 1993-1-1 recommends that a single angle in tension connected by a single row of bolts see Figure 1, may be treated as concentrically loaded over an effective net section for which the design ultimate resistance should be determined as follows

###### Where

- d
_{o}is the hole diameter; - e
_{2}is the distance of the centre of the fastener holes to the adjacent edge of the angle, perpendicular to the direction of load transfer (See figure 1). - γ
_{M2}is a partial safety factor as defined before. - t is the thickness of the leg of an angle.
- f
_{u}is the ultimate strength of steel.

The net area A_{net} is obtained from (clause 6.2.2) of BS-EN 1993-1-1. In angles of unequal legs, connected by the smaller leg, A_{net} should be taken as equal to the net section area of an equivalent equal-leg angle of leg size equal to that of the smaller leg.

Parameters β_{1}and β_{2} are reduction factors which are defined depending on the distance between holes (pitch p_{1}), according to Table 1; for values of 2.5d0 < p_{1} < 5d, these parameters can be determined by linear interpolation.

Finally, it should be noted that no matter the value given by the ultimate resistance of steel, it is always limited by the plastic resistance of the section.

#### Procedure for designing a Tension Member

- At the ultimate limit state, determine the design axial tensile force N
_{Ed}using appropriate partial factors. - Select the steel grade
- Select a section such that A>N
_{Ed}/f _{y} - Determine the design tensile resistance (N
_{t,Rd}) for sections without holes (N_{t,Rd}=N _{pl,Rd}). For section with holes N_{t,Rd}= min of (N_{pl,Rd}, N_{u,Rd}). - Verify that N
_{Ed}/N_{t,Rd}<1.0.

#### Worked Example

The maximum tensile force in the diagonals of a steel truss N_{Ed} = 350kN. The cross-sec

##### Welded Connection

The diagonals are made up by two angles of equal legs, but the connection is made only in one leg of the angle. Thus, the effective area can be considered equal to the gross area. Therefore, the following conditions must be satisfied.

##### Bolted Connection

In this case, the diagonals are made up of angles of equal legs connected by 2 bolts only in one leg. According to clause 3.10.3 of EC3-1-8, the following design conditions must be ensured.

The net area of the bolted section made up of two angles is given by

Since, N_{Ed }=350kN > N_{u,Rd }=193.19kN ; therefore, the chosen cross section is not appropriate. By adopting a cross section with enhanced resistance, for example, two angles 80x80x8 mm (A =24.6 cm^{2} and A_{net} =21.08 cm^{2}), then

Also see: Designing a Laterally Restrained Steel Beam

Thank you!

how to get cialis in australia – buy online cialis online cialis from canada

viagra in india cost – generic viagra mastercard viagra tablets in india

cialis generic 5mg – cheap generic cialis for sale cialis without prescription canada

ivermectin dose for covid – where to buy stromectol ivermectin 1mg

casino slot – casino slots gambling online casinos usa

can i buy ed pills over the counter – medicine erectile dysfunction erection pills that work

prednisone 15 mg tablet – generic prednisone for sale 60 mg prednisone

buy cialis lowest price – Cialis delivery tadalafil 120 mg

ivermectin tablets for sale walmart – buy ivermectin uk ivermectin 9mg

what is the best ed pill – mens ed brenda 35 ed contraceptive pill

ventolin for sale – gnrventolin.com ventolin price australia

cytotec pills – cytotec 200 canada cytotec 200mg price

doxycycline 50 mg tablets price – doxycycline over the counter south africa generic doxycycline 200 mg

neurontin 200 mg – neurontin 300 mg buy synthroid 0.88

where to get viagra online – viagra for women

generic cialis for sale in canada – tadalafil india buy online

vardenafil cena – generic vardenafil vardenafil 20mg nila vardenafil generic

ivermectin online pharmacy – ivermectin pills for humans ivermectin ebay

buy prednisone tablets online – 60 mg prednisone daily prednisone 5mg coupon

can you buy accutane online – accutane 30mg buy accutane 5 mg

amoxicillin brand name – buy amoxicilin 500 mg from canada amoxicillin for sinus infection

methylprednisolone dose pack no presciption – lyrica 100 mg price lyrica 75 mg

sildenafil uk over the counter – fsviag.com best prices on viagra

buy cialis lowest price – Cialis next day price of cialis for daily use

buy stromectol 6mg – ivermectin order ivermectin oral 0 8

is a doctor a physician stromectol for humans generic ivermectin ivermectin ivermectina in vendita

prednisone order – prednisone online paypal prednisone 0.5 mg

lasix price in south africa – furosemide 40 mg diuretic order lasix online