International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 11 (2016) pp 7426-7430
© Research India Publications. http://www.ripublication.com
The Industrial Accident Resulted from the Failure of Bolt
1
Hyun Wook YEO1, Jae Min LEE2 and Sang Won CHOI1, *
Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency, Ulsan, South Korea.
2
Department of Mechanical Design Engineering, Andong National University, Andong, South Korea.
Abstract
This study was to perform an investigation of the cause of
industrial accident, the cause of failure of anchor bolt to
collapse a steel frame structure on a construction site for two
workers on the steel frame structure to fall down and die.
Through the investigation of the accident site, the process of
accident and the situation of accident site were evaluated. The
finite element analysis on the steel frame structure was used
for an analysis, and the occurrence process of accident and the
circumstances of accident site when the accident occurred
were applied as analytic conditions.
According to the investigation of accident site and the finite
element analysis, it is evaluated that the asymmetric load by
the weight of steel frame structure and the external load under
insufficient fixture and support of steel frame structure led the
failure of anchor bolt to cause the collapse of steel frame
structure.
Also, it is confirmed that two anchor bolts at the back side to
receive the tensile stress among anchor bolts installed at the
pillar on the opposite of external force were broken in the first
place to lead the collapse of steel frame structure by the
feature of anchor bolt failure evaluated through the Von Mises
stress distribution.
Figure 1: Feature of steel frame structure before accident
Keywords: Industrial accident; Bolt; Failure; Finite element
analysis; Investigation of accident;
INTRODUCTION
In the industrial site, when bolts to be used to fasten
construction materials or machinery parts are failed due to
overload or fatigue, a serious industrial accident to cause a
severe damage may occur frequently. However, while there
are several studies about an analysis of engineering cause of
bolt failure in the industrial site [1, 2, 3], the analysis of cause
of bolt failure with respect to the investigation of cause of
industrial accident has not been studied much. In this study,
the investigation was performed on the cause of anchor bolt
failure to cause the serious industrial accident letting two
workers on a steel frame structure to fall and die.
The feature of steel frame structure at which the accident
occurred is shown in Figure 1 and Figure 2. The root diameter
of bolt was 20mm, and the nominal ultimate tensile strength
was 444N/mm2. For reference, the investigation of accident
site and the testimony by witness confirmed that the steel
frame structure was collapsed during the main assembly
(fastening of upper bolt connection) from the temporary
assembly.
Figure 2: Feature of steel frame structure fell after accident
METHODS
Through the site investigation of industrial accident, the
process of accident and the situation of accident site were
evaluated, and the collapsed steel frame structure was
modeled to be analyzed by using the finite element analysis
including the process of disaster and the situation of accident
site as analytic conditions. For concrete determination of a
possibility of anchor bolt failure, EN 1993-1-8:, Eurocode 3:
Design of steel structures. Part 1-8: Design of joints was
referred [4].
RESULTS
Anchor bolt failure process
Steel frame structure modeling
To predict the process of steel frame structure falling, the steel
frame structure modeled into the same dimension and the
same weight (9921.9kg) using the density and the external
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 11 (2016) pp 7426-7430
© Research India Publications. http://www.ripublication.com
two anchor bolts 5 and 6 (refer to Figure 6) located on the
opposite side of falling direction of steel frame structure out
of four anchor bolts on the right fixture receive the tensile
stress by asymmetric load from the weight of steel frame
structure [6], it was evaluated that they were damaged in the
first place among eight anchor bolts.
load (5000N of load each by two wires connected to the steel
frame structure) during the accident were applied. The steel
frame structure was modeled as the 3-D beam, the complete
fixture at both ends of lower part of steel frame structure was
applied as the boundary condition, and the modulus of
elasticity of 200×109N/m2, Poisson ratio of 0.285, and density
of 7850kg/m3 provided by the manufacturer of steel were
applied on the steel frame structure.
Review of the feature of anchor bolt failure
Figure 5: Feature of left anchor bolts failed
Figure 3: Modeling of steel frame structure (Load: weight of
steel frame structure and external load, Boundary: location of
anchor bolts)
Figure 6: Feature of right anchor bolts failed
The characteristics of anchor bolt failure evaluated through
the site investigation of accident are the followings:

Among four anchor bolts on the right side, the
threads of anchor bolt 5 and 6 located at the back
side (opposite of falling direction) were crushed by
tensile stress [6], but they were not broken. Since this
section receives the strongest tensile load by the
asymmetric load of the weight of steel frame
structure and by the pulling load of two wire ropes
connected to the steel frame structure among anchor
bolts, this section shall be deformed or failed in the
first place.
Figure 4: Von Mises stress distribution (Load: weight of steel
frame structure and external load, Boundary: location of
anchor bolts)
As a result of Von Mises stress distribution review [5], on the
right fixture at the bottom section of steel frame structure
(refer to Figure 4), the maximum stress was formed, and since
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 11 (2016) pp 7426-7430
© Research India Publications. http://www.ripublication.com


-Center of compression axis [refer to EN 1993-1-8:2005
Figure 6-15]
Except for 5 and 6, other anchor bolts were failed or
pulled out by instantaneous impact.
Comparing with the surface of failure of other anchor
bolts, the surface of failure of anchor bolt 2 at the
back side among four anchor bolts at the left side
was tilted to left.
Estimation of anchor bolt failure
The process of anchor bolt failure estimated based on the
feature of anchor bolt failure evaluated through the Von Mises
stress distribution [5] by the finite element analysis and the
site investigation of accident is the following:

The asymmetric load by the weight of steel frame
structure and the external load (pulling load by a wire
rope) crushed the screw threads of anchor bolt 5 and
6 at the back of right side for the steel frame structure
to be away from anchor bolt 5 and 6 →
Instantaneous failure of anchor bolt 7 and 8 at the
front of right side → Anchor bolt 2 was failed while
it was tilted to the left side by the collapsing steel
frame structure
(a) EN 1993-1-8:2005 Figure 6-15 c)
Review of anchor bolt safety
To analyze the failure of anchor bolt, the process of accident
and the situation of accident site were concerned to perform
the finite element analysis for two cases, and the EN 1993-18:, Eurocode 3: Design of steel structures. Part 1-8: Design of
joints [4] was referred to review the safety of anchor bolt.
Case1. Support of the weight of steel frame structure only
by anchor bolts without another support
To confirm whether the asymmetric load by the weight of
steel frame structure may be supported only with anchor bolts
without another support, the density was applied on the steel
frame structure modeled with 3-D Beam to apply the weight
of steel frame structure, and as the boundary condition, the
both ends of bottom of steel frame structure were completely
fixed to perform the review of anchor bolt safety.
(b) Dimension of end-plate installed anchor
Figure 8: Center of compression axis of anchor bolt
-Review of anchor bolt safety
Ft,Ed = Ft,Ed,M + Ft,Ed,N
(1)
Ft,Ed,M = (MEd × h)/(nv ×
∑ h2r )
(2)
Ft,Ed,N = NEd /nt
(3)
Ft,Rd = (K 2 × fμb × As )/(γM2 )
(4)
Where
Ft,Ed,M = The tension force from bending moment for one bolt
from bolt-row1
Ft,Ed,N = The axial force for one bolt from bolt-row1
MEd = The bending moment
h = The vertical distance from bolt-row1 to the center of
rotation axis (h = 23.8mm)
nv = The number of vertical bolt-rows (nv = 2)
Figure 7: Von Mises stress distribution (Load: weight of steel
frame structure, Boundary: location of anchor bolts)

Review of anchor bolt safety [4]
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 11 (2016) pp 7426-7430
© Research India Publications. http://www.ripublication.com
∑ h2r = The sum of the squares of the vertical distances
between bolt-row‘r’ and the center of compression axis
NEd = The axial force
nt = The number of bolts (nt = 4)
Ft,Rd = The design tensile resistance per bolt
K 2 = 0.9 [refer to EN1993-1-8:2005 Table 3.4]
fμb = The nominal ultimate tensile strength of the bolt (fμb =
444N/mm2)
As = The tensile stress area of the bolt (As = 314.159mm2)
γM2 = Partial safety factor for resistance of bolts (γM2 = 1.25)
[refer to EN 1993-1-8:2005 Table 2.1]
Table 1: Review of anchor bolt safety (Load: weight of steel
frame structure, Boundary: Location of anchor bolts)
MEd
NEd
Ft,Ed,M Ft,Ed,N
Ft,Ed
Ft,Rd Ft,Rd/Ft,Ed
1.25×108 -45692 2626050 -11423 2614627 100430 0.0384
(N·mm) (N)
(N)
(N)
(N)
(N)
※ For MEd and NEd,, the values at the location of “anchor
bolts under higher stress” in Figure 7 were applied.
Figure 10: Von Mises stress distribution (Load: external load,
weight of steel frame structure, and weight of workers,
Boundary: locations of braces, pipe supports, and anchor bolts)
Since the comparison value (Ft,Rd/Ft,Ed) between the design
tensile resistance (Ft,Rd) and the tensile force (Ft,Ed) by bending
moment and axial force is 0.0384, anchor bolts may not hold
the load by themselves.
Table 2: Review of anchor bolt safety (Load: external load,
weight of steel frame structure, and weight of workers,
Boundary: locations of braces, pipe supports, and anchor bolts)
Case2. Support of external load/weight of steel frame
structure/weight of two workers by braces/pipe
support/anchor bolts
To review the safety of anchor bolt supposing two braces and
four pipe supports which were installed at the site when the
accident occurred hold the steel frame structure without their
own failure or deformation, the analysis was performed by
applying external load (5,000N of pulling load each by two
wire ropes connected on the steel frame structure), the weight
of steel frame structure, and the weight of two workers as the
load on the steel frame structure modeled in 3-D beam, and as
the boundary condition, two braces and four pipe support and
the both ends of bottom of steel frame structure were
completely fixed.
MEd
NEd Ft,Ed,M Ft,Ed,N Ft,Ed
Ft,Rd
Ft,Rd/Ft,Ed
5.03×105 -10160 10567 -2540 8027 100430 12.5112
(N·mm)
(N)
(N)
(N) (N)
(N)
※ For MEd and NEd,, the values at the location of “anchor
bolts under higher stress” in Figure 7 were applied.
Under the assumption that two braces and four pipe supports
hold the steel frame structure without their own deformation
or failure, since the comparison value (Ft,Rd/Ft,Ed) between the
design tensile resistance (Ft,Rd) and the tensile force (Ft,Ed) by
bending moment and axial force is 12.5112, if braces and pipe
supports are not failed or deformed, the anchor bolst may not
fail.
Figure 9: Modeling of steel frame structure (Load: external
load, weight of steel frame structure, and weight of workers,
Boundary: locations of braces, pipe supports, and anchor bolts)
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CONCLUSION
Even though anchor bolts without other supports can’t hold
the asymmetric load only by the weight of steel frame
structure, if pipe supports and braces support the steel frame
structure without their own deformation or failure, the anchor
bolt may not be failed during the accident according to the
results of analysis of the failure of anchor bolt. Therefore, it is
evaluated that the asymmetric load by the weight of steel
frame structure and the external load led the failure of pipe
supports and braces temporarily installed at the accident site
for the steel frame structure to collapse. Also, it is identified
that the two anchor bolts at the back side to receive the tensile
stress among four anchor bolts installed at the right fixture to
be opposite of the external load were broken in the first place
International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11, Number 11 (2016) pp 7426-7430
© Research India Publications. http://www.ripublication.com
to lead the collapse of steel frame structure by the feature of
anchor bolt failure evaluated through the Von Mises stress
distribution.
CONFLICTS OF INTEREST
No potential conflicts of interest relevant to this article were
reported
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