Questions tagged [civil-engineering]

Questions that fall into the problem domain of civil engineering or one of its sub-disciplines. Questions about buildings or other structures could usually use the "structural-engineering" tag also.

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Why is the point of failure load lower than the peak load? [closed]

In a tensile test the peak load was 69kN, but the point of failure load was 60kN. Why is it lower?
Harrison De George's user avatar
18 votes
5 answers
3k views

How are passive houses made in very hot regions (like Saudi Arabia)?

I think, here is the main problem the difference between the internal and the external temperature. For example, in Saudi Arabia, in 50 C, a passive house needed probably much sophisticated planning ...
peterh's user avatar
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10 votes
3 answers
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Can the structural integrity of bridges be measured in real-time for safety?

As a follow up to this question, I wonder if structural integrity monitoring information can be provided real-time and to a sufficient degree that safety decisions can realistically be made from the ...
Mahendra Gunawardena's user avatar
9 votes
5 answers
968 views

How can I measure the thickness of a sedimentation layer in a closed tank?

Biogas slurry often contains sand and grit and organic matter that eventually sediments. Clearing thetank from sedimentation is expensive (plant downtime, additional equipment) and dangerous. So it ...
mart's user avatar
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9 votes
1 answer
4k views

Why don't we use principal maximum stresses when designing a structural element?

Consider a concrete column is under compression from top loading and also carries some shear stresses. If take a plane 2d element in the column with these stresses and rotate it to the point it gives ...
InstallGentoo's user avatar
8 votes
2 answers
10k views

How Can I Determine Multiple Discharges from a Pipe Network? (Knowing the Inlet Conditions)

I have little/no experience with pipe networks and have been searching for a methodology to calculate the discharge from multiple outlets of an oil pipe network with a single inlet. As far as i can ...
Petrichor's user avatar
  • 508
4 votes
1 answer
3k views

Deriving the deflection force equation for a beam that is fixed on both ends

I want to calculate the force-displacement equation for a beam that is fixed at both ends. I think I should use the superposition principle but I am not very sure how to get started. I know that for,...
user5785's user avatar
3 votes
2 answers
301 views

How exactly do forces transfer in different directions?

If we imagine the load being placed at the top of the below triangle, I realise that the downwards force is transferred into one which goes in a 'south east' and 'south west' direction down to the end ...
Nick Cory's user avatar
2 votes
3 answers
671 views

What's the purpose of a 'burger' lane in a roundabout?

I recently read about a newly proposed 'burger' lane across a roundabout. From what I can see, it bypasses the main point of a roundabout, a continuous circle of traffic with well defined rights of ...
AncientSwordRage's user avatar
1 vote
2 answers
130 views

A question on understanding the nature of static equilibrium

In the statics lesson, we do not think about the effects of forces on objects. In other words, we do not assume that an object can break, bend or twist. In the same situation, we can combine different ...
Bilgehan Yılmaz's user avatar
0 votes
0 answers
61 views

Continues beam deflection

does any one know how to derive the deflection equation of a continues beam of three span of equal length and equal UDL load Here's a link these two pictures shows my tries to solve the question
Fatma Alsatmi's user avatar
-1 votes
2 answers
651 views

Principal Planes and Principal Stresses

Consider that a state of plane stress exists at a point and the stresses acting on an element taken at that point are given as, The normal stress acting at any plane of this element inclined at an ...
Harshit Rajput's user avatar
23 votes
5 answers
8k views

Why exactly does a washer help distribute the stress around a bolt?

Usually the reason for having a washer under a bolt head is stated to be that it helps to evenly distribute the stress to the clamped material surface. But why is this? I would understand if the ...
S. Rotos's user avatar
  • 2,259
20 votes
2 answers
4k views

Why are truss bridges the way they are?

Just by taking a train ride across my home city I can see truss bridges like the one in above picture everywhere. There are numerous variations, but the most common design seems to be this. But why ...
S. Rotos's user avatar
  • 2,259
18 votes
1 answer
2k views

How to design a house to be cooled passively? [duplicate]

I live in Louisiana these days, in an area that is known for its numerous antebellum plantation homes (circa early 1800s). While touring one of these homes it was clear that almost everything about ...
Chris Mueller's user avatar
15 votes
4 answers
1k views

How should the public raise questions about unsafe structures in the United States?

In a program on NPR that I was listening to, there was a bit about a bridge that from the description sounded to a layman as unsound and is still in use. The program described it as an old wooden ...
user avatar
11 votes
1 answer
1k views

How to determine the lateral earth pressure in a double-walled cofferdam?

The design of a retaining wall commonly involves determining the lateral earth pressure using either Rankine theory or Coulomb theory. Both theories involve mobilising the shear resistance of a ...
Question Overflow's user avatar
10 votes
7 answers
5k views

Why do we pave roads instead of making them from removable parts?

If roads were made of removable parts, we'd probably have fiber cable internet everywhere by now I'd say. It'd be so much easier to install e.g. new electricity and water infrastructure and to ...
Yuri Borges's user avatar
10 votes
1 answer
313 views

Developing a stochastic differential equation model for concrete fibers

I am working on modeling concrete fibers (metallic fibers) as a mathematical model. My work is for my thesis. I am a PhD student of numerical analysis, but I am working on a real tunnel project. I ...
Khosrotash's user avatar
10 votes
4 answers
27k views

Why does the stress-strain curve decrease?

This is a stress-strain diagram I have noticed that the curve decreases between points C & D and between E & F. Why does that happen? I expected the curve to always increase since the ...
Eman.suradi's user avatar
7 votes
2 answers
2k views

How do you model a real-life truss in structural analysis software?

I am trying to recreate the following model of a wooden roof truss provided to me by a truss manufacturer: My question is twofold: What is the common/correct way to model the boundary conditions and ...
user32882's user avatar
  • 573
6 votes
2 answers
11k views

How to strengthen an I beam

To save on material, I am requested to design a continuously supported beam with a maximum bending capacity that is half of its maximum bending moment and to strengthen the beam at certain intervals ...
Jarard's user avatar
  • 73
6 votes
5 answers
14k views

Is hydrostatic pressure a dead load or a live load?

I have a structural analysis question. I want to know if the hydrostatic pressure in a water tank is a live load or a dead load and why?
Refaat Mohamed's user avatar
5 votes
2 answers
327 views

How do I conduct an experimental modal analysis with a three-axis accelerometer?

How can I compute the Frequency Response Function (FRF) if I use two three-axis MEMS accelerometer to measure the input excitation and output response? I have read from some books that the FRF can be ...
ice_lin's user avatar
  • 153
5 votes
2 answers
636 views

Is there a theoretical bound to how tall a structure can be built?

Assuming that there are no constraints on cost, land to develop, or supply of materials, is there a theoretical limit on how tall a structure can be built? What are the main physical constraints that ...
Paul's user avatar
  • 2,569
4 votes
1 answer
5k views

Losses through holes drilled in a pipe

I asked a previous question about pipe t-junctions with pipes of varying diameters, and it got me wondering... How are losses handled and calculated in pipes with holes drilled directly into them? ...
Petrichor's user avatar
  • 508
4 votes
4 answers
11k views

Why 0.2% of strain is considered while taking proof stress?

When a material does not show a distinct yield point then 0.2% of strain is considered and a line is drawn parallel to the elastic line and the corresponding stress is called proof stress. My question ...
user6538's user avatar
3 votes
2 answers
241 views

How to simplify a truss bridge diagram?

Hello I have this truss structure question. I understand that we need to determine the zero-force members first so that we can simplify the diagram. But I am not sure which one that I need to ...
Sobika42's user avatar
3 votes
2 answers
1k views

How does one build a waterproof basement?

I have been doing a bunch of research online into how to build a basement that is below the water table. The common wisdom is to "not waste the money doing that" but as someone who doesn't like to be ...
Micah Zoltu's user avatar
3 votes
2 answers
279 views

Cooling tower for nuclear power plants

Cooling towers for nuclear power plants often have the shape of a hyperboloid. At first glance, I thought that an obvious reason for this would be the smaller sectional area, meaning the tower would ...
Philipp Imhof's user avatar
2 votes
2 answers
139 views

Can a crisscrossed metallic skeleton resist earthquakes for buildings?

To follow up with my previous question on the seismic design of buildings, I would like to ask if it makes sense to support buildings with strong thick 'crisscrossed' metallic frames. I have the ...
Chong Lip Phang's user avatar
2 votes
2 answers
83 views

Can a horizontal foundation safeguard against earthquakes?

I have not taken any course in civil engineering. What I was taught was that a broad base would prevent something from toppling. So it makes me wondering instead of nailing the foundation of a ...
Chong Lip Phang's user avatar
2 votes
1 answer
84 views

L beam - Strange result

I have the following system (at P and Q there is a ball joint; the length of L beam is l; the PB and PA forces are applied at l/2 and are known; Fz is not zero and is known): The system has 0 degrees ...
Gennaro Arguzzi's user avatar
2 votes
1 answer
138 views

Controlled demolition of a sky scraper?

Sky scrapers are often found in dense urban environments. Is there a known method to controllably demolish a sky scraper with minimal collateral damage?
Sparkler's user avatar
  • 223
2 votes
1 answer
258 views

What practical geographical and engineering constraints limit the depth to which you can build underground?

Similarly, does there exist an index with the maximum building depths and heights in the United States? I found this map of soil types in California by UC Davis, but I don't think this directly ...
johnluttig's user avatar
2 votes
2 answers
7k views

Ceiling mounted punching bag without compromising structure or floor above

This question is regarding the safest way of installing a heavy punching bag of 100 lbs from the basement ceiling. Above the basement ceiling is a wood floor. The goal is to sleep soundly at night ...
Mike's user avatar
  • 21
1 vote
2 answers
165 views

Where is the contact point between screw spindle teeth and nut teeth?

So this is a screw press used to hmm disconnect the clamp connection (sorry if these are not the correct terms I really don't know how to translate it properly). Anyway, I think it's obvious what this ...
M. Wother's user avatar
  • 351
1 vote
0 answers
321 views

How to calculate monosymmetry index of an unequal angle? [closed]

I saw some formula involving integration. Is there a straightforward formula to calculate this instead given b, d, t and alpha angle between x-x and u-u axis?
Bornny's user avatar
  • 11
1 vote
1 answer
2k views

Conjugate beam (M/EI)

I dont understand how the diagram of M/EI of conjugate beam drawn , can someone explain about it ? According to conjugate beam theorem , i know that the M/EI represent the w(x) , which is force per ...
kelvinmacks's user avatar
1 vote
2 answers
306 views

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

Above is the definition of fundamental basic wind velocity from Eurocode 1. According to its instructions, wind loads on building are supposed to be calculated based on this velocity. It says that ...
S. Rotos's user avatar
  • 2,259
1 vote
3 answers
95 views

column bending stress under vertical earthquake load

In Fema national US&R response system - Structrual collapse technicican training manual It says: "There are also vertical loads generated in a structure by earthquake shaking, but as mentioned ...
upstream's user avatar
  • 457
0 votes
4 answers
886 views

Any way to approximate effect of two point loads with just one?

Imagine a 3D problem where the goal is to calculate the max. cantilever beam deflection. There are 4 equal point loads A, B,C,D separated equally from the beam's major axis. Is there a way to ...
Noideas's user avatar
  • 13
0 votes
1 answer
97 views

Is a granite block tunnel longer lasting than reinforced concrete? [closed]

Assumptions Building Process exists Waterproofing is able to be replaced Notes Please answer yes or no with the science backing. This question is only about the strength and lifespan. This ...
Dev Slocum's user avatar
0 votes
1 answer
66 views

Laying problem in designing axis points in static design?

First of all, there is a simple pattern plan on the halter. Here, we design an axis point passing through the midpoints of the columns and use it in the static calculation program. However, when we do ...
Bilgehan Yılmaz's user avatar
0 votes
1 answer
3k views

How do you determine flow distribution at a dividing T-Junction?

So I've been trying to find out how to determine what proportion of fluid will flow down a given path when a main line branches into two lines at a 90 degree T-Junction and I can't find anything ...
Lamijops's user avatar