Preliminary Design Calculations for Single Overhead Travelling Crane

Preliminary design calculations for single overhead travelling crane
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1.0 Introduction
An overhead crane is a type of crane , majorly found in heavy industrial
environments, usually referred to as a bridge crane. An overhead crane comprises
of elevons spanning the gap with a traveling bridge. A hoist, a crane's lifting
component, crosses the bridge. The crane is called a gantry crane (USA, ASME B30
series) or a goliath crane (UK, BS 466) if the bridge is rigidly supported on two or
more legs running on a fixed rail at ground level. The bridge can go down the
runways. The crane's lifting element is the hoist that is attached properly to a
trolley. The trolley is allowed to travel along the bridge. Such girders are found in
heavy industrial environments, factories and manufacturing plants, serving the
purpose of transporting (lifting and moving) objects within a given footprint from
one area to another. The bridge itself is a steel structure that is produced by
properly welding together steel plates. A commonly available rolled steel beam can
also be used, however. In any case, a preliminary design and assessment is
necessary to get a quick and easy first impression of the bridge girder cross
parameters (Behera, 2012).
Figure 1 single girder example (Indiamart, 2019)
2.0 Aims
The main goal of this paper is to present the following.
 Perform calculations for single overhead girder design
 To practice calculations of N-Q-M diagrams
 To be familiar with single girder overhead cranes, their design and standards
used in design
3.considerations
The crane is defined by the parameters define below
 The span of the crane will be 6m and with lifting capacity of 3.2 tones
 Wheel base for trolley is 600m with load distribution of 40% to 60%, distance
of trolley to beam end should be 100mm, at most. The beam is to be
considered as single supported.

4. calculations for preliminary design
Considering the maximum displacement for vertical movement to be 20mm, and
developed stress lower than the yield stress. The safety factor should be 1.15,
with frequency greater than 1.2 Hertz
Consider the girder frame span of 6m as shown,
Figure 2 illustration of simply supported girder beam, the point load is moving, the beam is assumed
as simply supported
To find maximum bending moments, consider the formulae below
Bending moments=perpendicular force × distance
Bending moment for the beam at span of 3 meters calculated as
Bm= Fr× d
Bm= 32kN × 3M
BM = 96 kN-M
direction of moments

BM= -96kM
(Tian, Zhang and Sun, 2012)
Bending moment for the beam at span of 3 meters calculated based on moving
support
Bm= Fr× d
Bm= 32kN × 3M
BM = 96 kN-M
BM = 96 kN-M
The position of maximum bending moments is at 3m from both ends. True
for simple supported beam
Figure 3 for the beam above, its Bm diagram will be plotted as follows