Static Engineering Supported Beams
Beams are to support the axial loads as well as for the transverse support and hence; they differ from the truss elements though both are the long and the slender structures. The axis point can be the same or the different as the beams joints can be welded together where it can transmit the bending moments in the beam.
Before going into the details of what is the function of static engineering in the supported beams, this is important to know what a supported beam is. The simple answer is that it is a beam which is supported by rolls without being attached with them. Yes, it rests on them but is not attached with them. At this stage there is one prominent force acting on the beam which is known as reaction force. This is important to know the role of the reaction force and its exact calculation.
Let’s come towards the question of what is a reaction force and how does it act on the beam. The reaction force is the applied force against the surface of something which rests on. The force is produced as a result of the stress of the resting surface and acts equally back. This reactionary force is the responsible force of the beam which supports it. If the beam is having some loads along with, you will find the reactionary force working against these loads as well. The loads here are the point loads and the surface of rest is a roller or like a sharp knife. You must know that the sharp edged knife or the roller pushes the load upwards where the resultant force becomes zero and as a result the load is in resting and static position.
This whole story can be explained in simple two lines principles.
- When a body is in equilibrium, it does not experience any force acting on it in any direction, in other words you can say ∑Fy= 0
- There is no resultant moment which can turn the body in any direction when it is in the state of equilibrium i.e. ∑ M= 0
My selected beam:
Below is the image of the beam, I have chosen for this assignment of mine and the later part will deal with its specifications and the selected steel.
The size of the beam is very important in the whole procedure. When you go for the selection of the beam, you have to be careful about many things as the size exactly plays the role of the pillar if it is chose correctly and vice versa. The structural design of the beam depends upon the size. Usually an I beam has the following dimensions.
Before I go for the next part of my assignment, I would like to mention the factors which are important to consider while choosing an I beam. These are flange thickness, flange width, web thickness, beam depth and Fillet radius.
Now when comes the question of selecting the exact size of the beam, it falls on the basic mechanical and design calculation which is easy if followed step by step.
- First thing important to know is the steel and load specifications for which the beam is expected.
- Bending moment is much important to know and it can be found by drawing the bending moment diagram. By this, you can find the value of maximum bending load moment.
- Below is the specification table of I beams
In x lb/ft | Area (inch sq) | d(in) | bf(in) | tf(in) | tw(in) | lxx(in⁴) | lyy(in⁴) |
W12X336 | 98.8 | 16.82 | 13.385 | 2.955 | 1.775 | 4060 | 1190 |
W12X305 | 89.6 | 16.32 | 13.235 | 2.705 | 1.625 | 3550 | 1050 |
W12X279 | 81.9 | 15.85 | 13.14 | 2.47 | 1.53 | 3110 | 937 |
W12X252 | 74.1 | 15.41 | 13.005 | 2.25 | 1.395 | 2720 | 828 |
W12X230 | 67.7 | 15.05 | 12.895 | 2.07 | 1.285 | 2420 | 742 |
- Get inertia of the selected beam
- You must know the beam depth of the selected beam
- Calculate the stress of the beam using the formula f/(d/2)=M/l
- Compare this value with the stress of the steel. This is in order to know the safety measures.
Now I would be coming to the ideal situation where this beam can be deployed. For this, a knee wall must not be a load bearing partition because if this is a load bearing partition; the case can be very complex and things can be out of control because in this case, the beams start supporting the things and the loads in the roof. And if this is not load bearing, the load of the roof is not worrisome and it can be transferred to the walls.
Shaft alignment is the basic key principle determining the quality of all the machines, thus you can say that circular shaft is an important part of all machines. Proper alignment can give the best results of stress bearing while improper alignment can trouble you in the stress bearing problems. If your shaft alignment is improper, it can lead you facing the breakdown of your machines. Before I go in details, let me explain what shaft alignment is. This is a procedure of through which machines are connected to the generators through alignment. If this alignment is improper, the stress can be increased and as a result, you will suffer the breakdown of machine.
This is very necessary for an engineer to understand the basic mechanism and the procedures of alignment. Misalignment can make you panic, there are two main types of misalignments; one is known as offset or the linear gap and the second is angular or known as gap. In the former alignment; there are two parallel shafts which have coinciding parallel center lines but in offset conditions. In the later type, the centerlines of the shafts are angular to each other.
In angular alignment which is my prime concern; there are simple steps to follow; in between the coupling shaft faces, insert the feeler gauge. Rotate the couplings halfway when the gauge is put. When the shaft is coupled, check the reading on the feeler gauge on fourth point. If there is difference in the reading, it means there is some difference of displacement in between the shafts. This problem can be solved if you place shims underneath the surface or lift the machinery.
By: Ammarah Khan
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