This document provides design requirements for lacing and battening systems used in steel structural elements. It discusses two types of lacing systems - single and double. It outlines 9 design requirements for lacing per Indian code IS 800, including angle of inclination, slenderness ratio, effective length, width/thickness, transverse shear force, strength checks, and end connections. It also discusses 7 design requirements for battening systems, including transverse shear force calculation, slenderness ratio, spacing, thickness, effective depth, overlap for welded connections, and notes battening offers less shear resistance than lacing.

1. GANDHINAGAR INSTITUTE OF
TECHNOLOGY
BE SEM :-6th
DEPARTMENT OF CIVIL ENGINERING
Active Learning Assignment of
ELEMENTARY STRUCTURAL DESING
(STEEL)
Topic : LASSING AND BATTERING SYSTEM
Prepared By:
PRAJAPATI HIMANSU 140120106085
Guided By
Prof. Mohammed Challawala

2. Introduction
 Typical joining of the components is done by two ways
1. Lacing
2. Battening
 Lacing bars or battern plates are not design as load carrying
members.
 They carry transverse shear force which occurs when the
column defects.

3. Lacing

4.  There are two types of lacing system.
1. Single lacing system
2. Double lacing system
 The lacing system should not be varied
throughout the length of the strut as far
as practicable.

5.  The single-laced systems on opposite sides of the main
components should preferably be in the same direction so that
one system is the shadow of the other.
 Cross (except tie plates) should not be provided along the
length of the column with lacing system, unless all forces
resulting from deformation of column members are calculated
and provided for in the lacing and its fastening.

6. DESIGN REQUIREMENT
FOR LACING
(AS PER IS : 800 – 2007
CL. 7.6 PG. NO.48)

7. (1) Angle of inclination(θ): (cl. 7.6.4)
 For single or double lacing system,
 θ = 40 ͦ to 70 ͦ To the axis of the built up member
 normally,=45 is taken
(2) Slendernes ratio(kL/r) : (cl. 7.6.5.1)
 KL/r for each component of column, should not be greater than
50. ( or)
 kL/r not greater than 0.7 *most favourable slenderness ratio of
the member as a whole

8.  The slenderness ratio of lacing shall not exceed 145
(cl.7.6.6.3)
(3) Effective length of lacing (le) :
For bolted connection :
For single lacing, le = L
For double lacing, le = 0.7 l
Where, L = distance between the inner end fastner
For welded connection :
Le = 0.7 x distance between the inner ends of welds

9. (4) Width of lacing bars(b) : ( cl, 7.6.2)
minimum width of lacing bar, b = 3d
Wh, D = nominal diameter of bolt
(5) Thickness of lacing (t) : (cl. 7.6.3)
For single lacing, t > Le/40
For double lacing, t > Le/60

10. (6) Transverse shear (Vt) : (cl. 7.6.6.1)
 Vt= 2.5% of the axial force in the column.
This force shall be divided equally among
the lacing systems in parallel Planes.
For single lacing
F=Vt / 2sin ϴ
For double lacing
F=Vt/4 sin ϴ
wh, F= axial force in each lacing bar

11. (7) Check for compressive strength
For lacing using Le/r min & fy = 250 Mpa
Find fcd from IS: 800, table -9 (c) pg. 42
For rectangular section buckling class is “c”.
So, Compressive load carrying capacity of lacing
Pd = (b x t) x fcd
If (b x t ) x fcd > F (axial force n lacing) …. OK
b*t = area of lacing
i.e. pd > F …. OK

12. (8) Check for Tensile Strength
 Tensile strength of lacing flat is,
Or
Whichever is less.
If …O.K. IS : 800 cl. 6.3.1, pg 32

13. (9) End connections :
The bolted connection for lacing may be two types as given case.
For case (a)
Resultant force on bolt = R = F
So, no of bolts required

14. For case (b)
Resultant force on bolt
So No. of bolts required
Strength in single shear
16 dia. Bolts = 29 kN
20 dia. Bolts = 45.3 kN

15. Strength of bolt in bearing (cl. 10.3.4)
(10) Overlap
 In case of welded connection, the amount of overlap measured
along either edge of lacing bar shall not be less than , four times
the thickness of the lacing bar (or)
The thickness of the element of main member, whichever is
less.

16. Battening

17.  Compression member can also be built up intermediate
horizontal connecting plates or angle connecting two or four
elements of column .these horizontal connecting plates are
called battens.
 The number of battens shall be such that the member is divided
into not less than three bays within its actual length

18. DESIGN REQUIREMENT
FOR BATTENING
(AS PER IS : 800 – 2007
CL. 7.6 PG. NO.51)

19. (1) The number of battens shall be
such that the member is divided
into not less than three bays.
(2) Battens shall be designed to resist
simultaneous

20.  Longitudinal shear
Vb = Vt C / Ns
 Moment
M=Vt C / 2N
Where,
Vt = transverse shear force
C = distance between centre to centre of battens longitudinally .
N = number of parallel planes of battens (2 usually)
S = Minimum transverse distance between the centroid of the
bolt/ rivet group / welding.

21. (3) Slenderness Ratio : (cl. 7.7.1.4)
 The effective slenderness ratio of battened column
shall be taken as 1.1 times the ,the maximum actual
slenderness ratio of the column, to account for shear deformation
effects.
(4) Spacing of battens (C) : (cl. 7.7.3)
 For any component of column,
(1)
(2) of built up column (which ever is smaller)

22. (5) Thickness of battens (t) : (cl. 7.7.2.3)
wh, = distance b/w the inner most
connecting lines of bolts,
perpendicular to the main member
(6) Effective Depth of battens (de) : (cl 7.7.2.3)
 de > 3/4 * a …for intermediate battens
 de > a,……. ...For end batten
 de > 2b , …… For any battens
Wh, de = distance between outermost bolts longitudinally
a = distance between centroids of the main member
b = width of one member

23. Overall depth of battens
D = de + (2 * end distance)
(7) Transverse shear (Vt) : (cl. 7.7.2.1)
Vt = 2.5 % of the factored axial column load
(8) Overlap (cl. 7.7.4.1)
for welded connection, the overlap shall be not less than four
times the thickness of the battens
It should be noted that the battens columns have least
resistance to shear compared to column with lacings