Wasabi
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Reinforced concrete by steel, poor durability, why?
0 votes

There are multiple avenues through which this can be approached. One is the economics of the construction. As you've mentioned, concrete structures are far cheaper to build than steel, though the ...

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Is bending moment along a beam independent of the cross sectional area of the beam?
3 votes

You seem to be mixing up a few concepts. As others have mentioned, bending moment is independent of a structure's cross-sectional dimensions. After all, bending moment is simply the sum of $F_i\ell_i$,...

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a model of a solid using trusses to approximate internal stresses?
3 votes

Not only can this be done, but it also is done for concrete structures all the time. The shear reinforcement in concrete beams is calculated using Mörsch's truss analogy model: Source The concrete ...

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Assuming identical hole perimeter, for which shape is the stress minimized?
2 votes

It depends on the loading conditions. It's important to note that the stress concentrations can be intuitively understood as created by the load's need to deviate from the hole. The larger the width ...

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What are the units used in beam bending equations? Do they matter?
2 votes

What's an equation? In life there are two types of equations: theoretical equations are obtained from first principles: make some assumptions and then play around with variables until you get a ...

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Is an axial force applied at the centre of a beam considered a compressive force, tensile force, or both?
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2 votes

I think your big misunderstanding is in this paragraph: [...] if I were to scan, starting from the leftmost side towards the right. I would initially see a compressive force onto the beam from R, ...

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is this a picture of a plate girder train bridge or a deck truss train bridge?
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2 votes

It's a truss bridge. A quick Google Image search will make the difference between the bridge types clear. This is a plate girder bridge: And this is a truss bridge: Basically, a girder bridge uses a ...

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Exactly what makes steel-concrete composite beam better than pure steel?
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4 votes

Some other answer have touched upon this, but I think it needs to be made explicit: Your mistake is in thinking that civil engineering is about making the lightest structure possible. It's not. ...

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How is any kind of structural reliability achieved if the probability of annual wind speed exceedance is 0.02?
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0 votes

Buildings are typically designed with a 50-year lifespan. So a 2% yearly chance of passing the limit makes intuitive sense. But you're right: that'd basically mean we expect the structure to collapse ...

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Civil Engineering - Detailing of free draining backfill and modelling of hydrostatic pressure in retaining walls
1 votes

I'm not a geotechnical engineer, but I believe the gravel is there precisely to prevent the soil behind it from getting saturated. That is, if the soil gets saturated, the hydrostatic pressure will ...

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Confused about internal hinges for calcualting reactions
3 votes

An extended discussion on internal vs. external forces We usually like to describe hinges as "places where the moment is always zero." But, wait a minute, the moment is always zero anywhere ...

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How do the constraints imposed on a material increase the stiffness?
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7 votes

Let me see if I understood it correctly: You have a rubber block under a uniaxial load (compression or tension). That block may or may not be constrained on one pair of sides (the load is applied ...

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Does a photon impart energy on a surface (to raise its temp) if it goes THROUGH that surface?
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1 votes

Photons either pass through a given material or they don't. If they pass through, it's as if the material isn't there as far as they're concerned (ignoring refraction). If they get absorbed, then they ...

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Hollow (rectangular) sections versus solid sections
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0 votes

You are correct on both counts. For members under tension, both cross-sections should behave equally, since the limit to the allowable tension force is simply: $$P = f_y A$$ Where $f_y$ is the ...

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Steel frame connection
1 votes

The lesson to learn here is that you need to design your structure such that it matches your analytical model. Does your model have a transfer of moment between the beam and the column? Then you need ...

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What is "per unit strain"?
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1 votes

While I completely agree with @NMech's answer, let me take a different approach. As I see it, the problem is that you're forgetting something: look at the right-hand side of that equation: $IR_gG_F$. ...

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In FEA, why is the stress at an interior angle (<180 deg) is a singularity and an exterior angle (>180 deg) it is not?
1 votes

Fair warning, I'll be anthropomorphizing and using metaphors throughout this answer. It helps to think in terms of how the applied force "flows" through the element. It "wants" to ...

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Is static determinacy regardless of the number of reactions?
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1 votes

We usually describe structures as either statically determinate or indeterminate. However, this determinacy is actually two-fold: there's internal and external determinacy. External static determinacy ...

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The difference between two load combinations in LRFD
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1 votes

Dead loads can, in some cases, be beneficial to the structure's safety. For instance, say you have a simply-supported beam with a cantilever and you want to find its bending moment envelope. Depending ...

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Why are actions combined in this way Eurocode?
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1 votes

If we look at each of those fractions individually, their meaning is obvious. Obviously, for a structure under axial load (or bending moment), the applied force must be lower than what the structure ...

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Why loads in serviceability limit states usually don't include factors of safety?
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1 votes

There's a reason why they're called "factors of safety" The answer to your question is in its title. When designing a structure, we need to make sure of two things: that the structure will ...

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Why doesn't prestressed concrete crack at the top before the load is applied?
0 votes

For starters, what makes you think the concrete doesn't crack at the top? Let's assume for a second that it does crack. Well, if we were dealing with a pure concrete beam, that'd be a big problem ...

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What parameter to lower elastic elongation of a rod under tension
1 votes

As insinuated by @Solar Mike's comment, a good first step is to think about the equation which defines elongation, Hooke's Law: $$\begin{align} \sigma &= \frac{F}{A} = E\epsilon \\ \therefore \...

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What is "hyperstatic moment"?
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2 votes

To understand the hyperstatic moment, we need to first remember that prestress is, by definition, the application of an internal stress state on the beam. Therefore, it cannot generate external loads ...

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How can deflection and spring constant of cantilever beam stack be calculated?
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2 votes

This is a case of a variable-cross-section beam. What you need to do in these cases is separate the cantilever into two parts: near the support it has one cross-section, near the free end, another. ...

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How to check if bending moment diagram is correctly drawn
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0 votes

In such exercises, I suggest doing things by steps. Your work goes from the equilibrium equations directly to the internal force equations. Instead, I suggest doing one thing at a time. The ...

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Determine the reactions on supports A and C and write the functions of the internal forces for the beam sections AB
1 votes

This is a statically determinate structure (four reactions minus one release equals three static equilibrium equations). So we should be able to do this using simple statics: $$\begin{align} \sum F_x &...

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How to determine the fixed end moment?
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1 votes

It can't be done Indeed, this problem is unsolvable using only equilibrium equations. Broadly speaking, structures can be split into three categories: hypostatic: when there are too few supports to ...

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Bending moment calculation
0 votes

It depends on how you choose to interpret those images. When doing simple models and especially when one's at an early stage in their education, the answer is that the three are equivalent. The reason ...

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Understanding Pressure
0 votes

The thing to understand about water pressure is that it is always equal in all directions. Sure, the value of the pressure is defined by how deep underwater you are, but that doesn't mean you'd feel ...

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