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1

One does not want the rupture in the grips; that makes elongation and reduction of area measurements very difficult. Also, notch sensitive materials will rupture in the grip area unless the the grips are significantly larger cross-section than the gage length. For notch sensitive materials even the shoulders must have a long gradual taper to avoid shoulder ...


3

The stress is not uniform near the grip because there is a biaxial state of stress. There is the axial force the compression force from the grips. That is the reason that if the Cross-section was uniform the failure would start from the grip. the mental image is the following: If you have a ballon that you apply force from one end, and at the same time ...


2

As far as I know, the enlarged part is used to grip the specimen. The fillet and smaller cross-section area is where the necking happens and that smaller cross-section is designed to avoid necking on the grip. I think the failure does not happen at the end. If its completely axial load, the whole specimen will elongate and become thin, then the failure would ...


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As the name of the subject, "Statics", suggests, the beam and every piece of the segment (AF & FD), that is imaginarily separated from the beam, must stay static in its own system. In structural terms, it means the beam and the segments must remain in "structural equilibrium", either in the global scene/system, or the local scene/...


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The moments on the two sides of the FBD are the sum of the area of shear before the two sides of the cut, they are always acting in opposite directions to restore the beam from a curved deflection to the straight line. They have no direct relation to the shear if that has confused you. So that you can imagine how the shear is not related to the moment ...


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The reason why this the forces and moments are opposite, is that the cross-section on the edge belongs to both the right and the left. (I tend to think of it as an imaginary infinitesimally thin section, although it's not strictly correct). Additionally this cross-section is "static" in space. Therefore the sum of forces should be equal to zero. So ...


1

When modelling district heating network, I came across this figure showing recommended pipe diameters with respect to the flow velocity (of hot water). I hope it illustrates how maximum flow velocity should be considered w.r.t. pipe parameters. To evaluate the effect of the chosen design guideline, it has been differentiated between four design guidelines. ...


1

Concrete performs best (and more consistently) when loaded in compression. (Putting concrete in tension is not good practice). When a beam is pre-stressed essentially the rebars are acting as a spring that compresses the entire beam. Thus more of the material is in a state that can perform in a useful manner. On the other hand, the rebars also perform better ...


2

Efficiency is a relative term in comparing structures built using different materials and technologies. For prestressed concrete, it is most justifiable to compare it to its next kin - cast-in-place concrete. The efficiencies mainly lie in two aspects - load carrying capacity and cost. 1) Load carrying capacity: i) For the same size and span length of a beam,...


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The rebars just for the sake of being embedded in the concrete do not work! It has to be stretched to work. Hooks law, $ \ F=Kdx, \quad K = E*A$ That's why we place the rebars on the bottom not near the center of the beam, to give them elongation. So a lot of good concrete that could be used for compression has to crack open stretching with rebar while ...


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The fundamental reason is that at high voltages, buried cables get capacitively coupled to the surrounding earth and the buried transmission line experiences more losses per mile of run than an overhead line. The practical reason is that it is easier to repair cables when they are overhead than when they are buried, and when overhead, they do not require a (...


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The utility company and the local government are different entities, each has its own priorities and budgets, and the life cycle of the road and utility lines usually differs, such makes coordination extremely difficult except for new development. Direct bury the powerlines underground poses a hazard for the latter roadside construction activities, routine ...


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This is a biased answer, based on gripes of life experience (not as an engineer) (this by no means is the standard). I think this is routinely done in some parts of the world. The main drawback is what happens (in some parts of the world again) when there are problem. What I mean is that laying the power cables under the road is something that requires a lot ...


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For the system shown, intuitively we can cut the beam at halfway between the support points G & H, so the left half is a mirror image of the right half regarding geometry, loading, support reactions, and member internal forces, so we can analyze half of the structure to obtain the same results. However, the trick is what type of support needs to be ...


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For small equipment mounting, let me introduce two simple methods: 1) Rigid Rotation Method (Classic) 2) Cantilever Method (Conservative approximation) Assume cantilever action, for which the applied load rotates about the point "A", and the rotation is restricted by the two bolts farthest from the point "A". Conclusion: I recommend ...


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As mentioned in kamran's answer its very important that the bar is rigid. Otherwise the following analysis is not relevant. Although you don't seem to consider it this way, -if the beam is rigid enough-, then the fulcrum at the far left edge of the beam (not on B1, so the force there is not zero). The equation I derived is based on that assumption, which is ...


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Assuming the lever is rigid enough not to bend to simlify our estimate: The lever will rotate about B1 bolt because it can not penetrate the concrete block. So B2 to and B3 will share the 288N proprtionaly to their distance from B1. Lets call their reactio RB2 and RB3 respectively. $$R_{B3} =(1250-742=508)/(1250-912=338)*R_{B2}= 1.5 R_{B2}$$ By substituting ...


1

You have left out the most important data of the concrete - grade 25 concrete (M25), which has a compressive strength ($f_c'$) of, approximately, 3600 psi (or 3625 psi to be close to exact). I assume you are an engineer, from here you shall be able to determine its elastic (Young's) modulus, maximum tensile strength prior to crack, and the allowable stresses ...


1

The simplest weight-moving mechanism in ancient times is pictorially shown below. The weight was placed on wood logs and rolling ahead. The movement was done by the pulling and pushing of the slaves using ropes, rods/levers, and hands. You can estimate the number of slaves required if you know the following parameters - $W$(weight), $\mu$(rolling friction ...


1

This is not an answer. It is an extended comment on why this calculation is impossible - IMHO - to be accurately answered. For the calculations, I'll assume that the maximum pull force of a person on a rope is on average his body weight (think about pull ups - although many people can't do them). So a 80 kg person can produce a 800 N push force. Perfect ...


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When there are internal hinges on a continuous beam, the first step is to separate the beam into segments at the hinges, then write the equilibrium equations for each segment, and finally solving the equations. For statically indeterminate beams, you should resort to using other methods. Case 1) To the left beam segment, $\sum F_Y = 0, A_Y = B_Y$ $\sum M_B =...


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Amount of Water Used The amount of water used in the USA in 2015 for all uses other than thermoelectric power (1) (read: to cool power plants) was 189B gal/day, or 715M m^3/day. Amount of Energy Needed The amount of electrical energy it takes to desalinate ocean water is in the range of 3-5.5 kWh/m^3. Therefore the amount of electrical energy it takes to ...


2

Yes, it can be used in foundations and subbases of roadways if the rocks meet property and gradation requirements. However, crushed stone/gravel is often the choice for the base material. Base course is a layer of the pavement structure immediately beneath the surface course. It typically consists of high quality aggregate such as crushed gravel, crushed ...


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It looks like it's being used to backfill narrow watermain trenches with gravel. Edit: It's also used for filling up an excavator bucket with gravel -- so that the excavator doesn't need to move out of position to go over to the gravel pile. It's hard to tell from the photo, but the excavator in the back is straddling a narrow trench. And the gravel pile ...


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They may be unrelated parts. The top part looks like a column and baseplate that was later cannibalized and part of it was cut off to be used in a different assembly, say a 90-degree elbow. The lower photo looks like an attachment for a small excavation machine.


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