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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN

0976 – 6316(Online) Volume 5, Issue 3, March (2014), pp. 333-339 © IAEME

333

STUDIES ON STRESS CONCENTRATION AT BOLT HOLE LOCATION IN

LAP JOINTS USING FINITE ELEMENT ANALYSIS

H.K. Harsha1, R.P. Rokade

2, A. Sivakumar

3

1(M-Tech Project student, VIT University, Vellore – 632014, E-mail: [email protected])

2 (Principal Scientist, CSIR-Structural Engineering Research Centre, Chennai – 600113)

3(Professor and Head of Structural Engineering Department, VIT University, Vellore – 632014)

ABSTRACT

Concentration of stresses at the bolt hole locations in the direction of load influences the end

distance requirement and failure pattern e.g. bearing or end tearing. The optimum end distance

should be such that the joint strength should be at least equal to the net section capacity. In this

paper, the stress pattern of lap joint is studied. A three dimensional (3D) Finite Element (FE) lap

joint model is developed using general purpose FE software, Abaqus. Non-linear finite element

analysis is performed considering the stress strain behaviour of plate and bolt materials; interaction

between bolt and plate surfaces. Further contact between bolt shank portion and bolt hole inner

surface is modelled to simulate bearing interaction. Parametric study for variation in end distance in

multiple of bolt hole diameter is performed to estimate the optimum end distance with failure load.

The failure criteria and respective stress patterns are compared with codal provisions given in IS

800-2007.

Keyword: Lap-Joint, Bolted Connection, Finite Element Analysis, Bi-Linear, Bearing, Friction Grip,

Bolt Hole, End Distance.

INTRODUCTION

The structural joints are the critical elements of structural assembly and the main purpose of

it is to, transfer the forces across different members. The bolted connection is the most commonly

used method to join the structural members. In bolted joints, the stress concentration will develop

around the bolt hole which will cause premature failure, if the end and edge distances are not

sufficient. Hence, a parametric study is necessary to find the optimum end distance. Ungkurapinan.

N., (2000), studied the effect of variables like friction and slip that affect the joint behaviour in

bolted joint connection. The transfer of load in the applied direction was considered as shear.

Different friction co-efficient considered in the analysis and optimum value evaluated for effective

INTERNATIONAL JOURNAL OF CIVIL ENGINEERING

AND TECHNOLOGY (IJCIET)

ISSN 0976 – 6308 (Print)

ISSN 0976 – 6316(Online)

Volume 5, Issue 3, March (2014), pp. 333-339

© IAEME: www.iaeme.com/ijciet.asp

Journal Impact Factor (2014): 7.9290 (Calculated by GISI)

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IJCIET

©IAEME



334

force transfer. Swanson J.A., et. al., (2002), studied the T-stub flange models consisting rectangular

and triangular elements. The models were incorporated with bi- linear material characters, non linear

material behaviour and several contact interactions. Cloud. G.L., et. al., (2005), analysed

experimentally and numerically stress distribution inside the thick bolted plate along the bearing

plane normal to the plate surface for both composite and isotropic materials. Jespersen. M., (2011),

explained the contact surface between the lap joint plates and between the bolt and bolt hole. Balc.

R., et. al., (2012), analysed the behaviour of beam to column end bolted connection using Abaqus. In

FE modelling the pre tension of high strength bolts and friction between connecting components

were considered and the transfer of forces was realized through friction due to clamping action

between the connection elements. Liman. M., et. al., (2012), investigated assembly of two segments

of tower and termed it as new type of lap joint. The accuracy and efficiency of the model was

checked by generating the contact interaction with different friction values.

Extensive studies have been carried out on hot rolled and composite material connections.

The finite elements models were developed for these materials. In this paper, FE modelling

techniques has been developed for lap joint using cold formed steel sections. A bi-linear analysis was

carried out to determine the stress concentration at bolt hole and its effects on the end distances. The

analysis results were compared with codal provision.

STUDIES ON BOLTED LAP JOINT

A simple lap joint is considered for the cold form steel plate. The material properties used in

this analysis are taken from the Coupon test results. The coupon’s were fabricated and tested in

accordance to the ASTM Standards. The mechanical properties for cold form steel specimens based

on coupon tests are as follows, yield strength, fy = 350 MPa, Ultimate strength, fu = 490 MPa, and

Young’s modulus, E = 2.198 MPa.

The lap joint consists of high strength 8.8 grade 16 mm diameter bolt along with the 6 mm

high tensile plates used for modelling of cold form sections as shown in Fig.1. The edge distance and

initial end distance is taken as 1.5d0 as recommended in IS 800:2007. Further the joint is analysed for

various end distances 1.0d0, 2.0d0, 2.5d0 and the results were compared with respective failure pattern

and stress concentration at bolt hole locations.

Fig.1: Lap Joint



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Various modes of failure are considered for evaluating the lap joint capacity as per IS

800:2007 are as follows.

Net section capacity criteria:

where Tdn = design strength in tension of a plate, An = net effective area of the member, fu =

ultimate stress of the material, γm1 = partial safety factor for failure at ultimate stress.

Shear capacity of bolt:

Where fu = ultimate tensile strength of a bolt, nn = number of shear planes with threads

intercepting the shear plane, Anb = net shear area of bolt at threads, ns = number of shear planes

without threads intercepting the shear plane, Asb = nominal plain shank area of bolt.

Bearing capacity of plate:

where kb is smaller of , , 1.0. e = end distance of the fastener along bearing direction,

d0 = diameter of the hole, fub, fu = ultimate tensile stress of the bolt and the ultimate tensile stress of

the plate respectively, d = nominal diameter of the bolt, t = summation of the thickness of the

connected plates experiencing bearing stress in the same direction.

Tension resistance of bolt:

where fub = ultimate tensile stress of the bolt, fyb = yield stress of bolt, An = net tensile stress

area, Asb = shank area of the bolt, γmf = partial factor of safety.

The material properties based on coupon test and the capacities for various failure modes as

mentioned above except for the bearing capacity is given in Table 1.

Table 1: Joint capacity

sl.no Modes of failure Capacity

(KN)

1 Net section capacity 78.32

2 Shear capacity of bolt 74.29

3 Tension resistance of bolt 90.33

Since, plate bearing capacity is influenced by end distances, it is calculated for four different

end distances 1.0d0, 1.5d0, 2.0d0, 2.5d0 and indicated in Table 2.



336

In comparison to all the possible mode of failure listed in IS 800:2007, the joint failure may

govern the shearing of connecting plates with end distances. The joint capacity for this mode of

failure is calculated considering the block shear guidelines for shear capacity part as per IS 800:2007,

as follows

Fig.2: Plate Shear failure planes

where V = Shear capacity of plate, n is the number of shear planes developed in the load

applied direction, (n = 2) as shown in Fig.2., e is the end distance selected, d0 is the bolt hole

diameter, t is the thickness of plate, fy is the yield strength of plate.

The joint capacities for above mode of failure with various end distances e.g., 1.0d0, 1.5d0,

2.0d0, 2.5d0 is calculated and given in Table 2 along with bolt bearing capacity.

Table 2: Bearing capacity and shear capacity

(d0 = 18 mm), (t = 6 mm), (fu = 490 MPa)

sl.no End distances Bearing Capacity

(KN)

Shear capacity

(KN)

1 1.0d0 31.04 39.68

2 1.5d0 47.04 59.52

3 2.0d0 63.03 79.36

4 2.5d0 78.36 99.27

FINITE ELEMENT MODELLING

The 3-dimensional Finite Element (FE) model for lap joint is developed using general

purpose FE software Abaqus. The FE model is capable to simulate the bi-linear material

characteristics and the non linear geometric (deformation) behaviour. FE technique is one of the

most powerful tool to simulate the experiments numerically as the results are very close to the test

results depending on the refinement of mesh size and other factors. Further the FE modelling saves

the time and cost in comparison to actual experiments.



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Fig.3: FE model of Lap Joint

In present study, the FE model for lap joint is developed in Abaqus as shown in Fig.3. In lap

joint the force transfer between the plates is by friction developed between plate surfaces under the

action of bolt pretension force. The same has been modelled using the contact surface interaction

module available in Abaqus. The contact between plates is modelled with coefficient of friction of

0.4 defined in the interaction property of tangential behaviour and allowing an elastic slip of fraction

of surface characteristics dimension. The normal behaviour of friction is created by generating a hard

contact as Augmented Lagrange standard. Similarly the interaction between bolt shank portion and

the bolt hole surface is also developed.

The degree of accuracy of the results for finite element analysis is depending on the optimal

size of mesh. The bolt in lap joint FE model is meshed using C3D8R, a eight noded quadratic brick

element with reduced integration and hourglass control and the plates are meshed with C3D8I a eight

noded quadratic brick element with incompatible modes. The bolt, bolt head and nut were modelled

as a single object to limit the contact surfaces in a model. The analysis is carried out by applying the

load uniformly in increments on the x-z surface of one of the plate as a uniform pressure and the end

restraints are provided in opposite side x-z surface of the other plate. The results and respective

failure criteria is given for each analysis in Table 3 and the stress distribution along with deform

shape for each analysis is shown in Fig.4.



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Table 3: Comparison of FE capacity with calculated Joint capacity

(d0 = 18 mm), (t = 6 mm), (fy = 350 MPa), (fu = 490 MPa)

sl.no End distance

criteria

FE failure

load

(KN)

Calculated

Joint

capacity

(KN)

Joint

capacities

without

material

factors (KN)

Difference Failure

criteria

1 1.0d0 46.03 31.04 38.80 18% Bolt bearing

2 1.5d0 68.41 47.04 58.80 15% Bolt bearing

3 2.0d0 84.61 63.03 78.78 8% Bolt bearing

4 2.5d0 85.17 74.29 92.86 -9% Bolt shearing

a) End distance 1.0d0 b) End distance 1.5d0

c) End distance 2.0d0 d) End distance 2.5d0

e) End distance 2.5d0

Fig.4: Stress contours and deformed shape for lap joint plate and bolt.



339

CONCLUSIONS

� The 3D FE models for lap joint are developed using Abaqus and procedure for the same is

provided.

� The FE analysis failure loads are higher as compared to the joint capacities calculated as per IS

800:2007 provisions.

� The FE analysis failure loads in comparison to the joint capacities calculated excluding the

material safety factors are higher by 18%, 15% and 8% for end distances 2.0d0, 1.5d0 and 1.0d0

respectively.

� The joint capacity for end distance 2.5d0 is higher by 9% as compared to FE failure load.

� The failure modes for lap joints with end distances 1.0d0, 1.5d0 and 2.0d0 are in bolt bearing

whereas the same for lap joints with end distance 2.5d0 is in bolt shearing.

� The studies are based on FE analysis and codal calculation for lap joint capacities. Further it is

required to conduct experiments for conclusion purpose.

ACKNOWLEDGEMENT

We are thanking to Director, CSIR-SERC, for permitting to publish this paper in the

proceedings of International conference on 'Advances in Civil Engineering and Chemistry of

Innovative Materials-ACEMIN' 14.

REFERENCE

1. Abaqus / standard user manual, Version 6.12.

2. Ungkurppinan, N., “A Study of Joint Slip in Galvanized Bolted Angle Connections,” Master

Thesis, University of Manitoba, Winnipeg- Manitoba, April 2000.

3. Swanson, J.A., Kokan, D.S., and Leaon, R.T., “Advanced finite element modeling of bolted T-

stub connection components,” Journal of Construction Steel Research, Vol.58, No.5, pp.1015-

1031, Aug 2002.

4. Cloud, G.L, Iancu, F., Ding, X., and Basavaraju, B.R., “Three-dimensional investigation of

thick single-lap bolted joints”, Journal of Experimental Mechanics, Vol.45, No.4, pp.351-358,

August 2005.

5. Jespersen, M., “Angle Bar Bracings in Lattice Structures,” Master Thesis, Technical University

Of Denmark, Jan 2011.

6. Balc, R., Chira, A., and Chira, N., “Finite element analysis of beam to column end plate bolted

connection,” Civil Engineering & Architecture Vol. 55, No. 1, pp. 24-29, July 2012.

7. Limam, M., Heistermann, C., and Veljkovic, M., “Analysis of a Lap Joint Friction Connection

Using High Strength Bolts,” Nordic Steel Construction Conference, Norway, Sept 2012.

8. A.S Jeyabharathy, Dr.S.Robert Ravi and Dr.G.Prince Arulraj, “Finite Element Modeling of

Reinforced Concrete Beam Column Joints Retrofitted with GFRP Wrapping”, International

Journal of Civil Engineering & Technology (IJCIET), Volume 2, Issue 1, 2011, pp. 35 - 39,

ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

9. Y. Vanhove and C. Djelal, “Friction Mechanisms of Fresh Concrete Under Pressure”,

International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 6, 2013,

pp. 67 - 81, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

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