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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28 views

Hencky nets on the *interior* of a closed domain

The equations for Hencky nets are usually solved in the exterior of some domain; typical examples are the upper half plane or the exterior of a circle. I would like to know about examples of these ...
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3answers
85 views

How does an arch transfer vertical load?

I am hoping that someone can explain to me how, physically, an arch transfers a purely vertical load (Fy) into a diagonal force to the abutments of the arch. I understand that the y and x components ...
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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 ...
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50 views

what does the EI in deflection of beams formula stand for?

I know it has something to do with young modulus, but how do you apply it in real life. ( say you have a reinforced concrete beam)
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1answer
37 views

Jointed reinforced concrete tie-bar smoothness

We know that in Jointed Reinforced Concrete pavements we use dowels and tie bars. Why are dowel bars Smooth and tie bars are deformed? Dowels are used to transfer about 40% of the load from one slab ...
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38 views

Calculating discharge from a reservoir as the head of water decreases

Due to the dry weather we've been experiencing in the UK I need to calculate the discharge rate from some reservoirs for work and how the dropping water level will result in a reduced head and so a ...
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Help calculating discharge rate from a reservoir as the water level drops?

I could do with some help calculating the discharge rate from a reservoir and factoring in how that flow will decrease as the head of water decreases. The information I have is: Maximum height of ...
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4answers
160 views

Can/do Civil Engineers do “hands-on work” such as physically partake in building the infrastructure as well?

Peace and Blessings. While doing research about the Civil Engineering profession, I see that they typically do a lot of computer work, desk work, meetings, and fieldwork in the sense of overseeing ...
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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 ...
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1answer
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Can I use empirical formula ,time period T=0.1*N, (N= number of floors) to find fundamental frequency of vibration of Tesla's lab building in1890?

I want to know ,can I use the empirical formula time period T=0.1*N, where N = number of floors, to find the fundamental frequency of vibration of Tesla's laboratory building in which he performed ...
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1answer
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What is the physical significance of bolt elongation length?

Eurocode: design of steel connections mentions something called "bolt elogation length", defined as the grip length of the bolt plus half of the sum of bolt head height and nut height. But ...
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1answer
30 views

Neutral axis and 2nd moment of area [closed]

Does anyone know how I would find the horizontal neutral axis (yc) and 2nd moment of area of this cross section? (R = 210 mm) I know that and that there needs to be the same amount of area on either ...
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61 views

Why do we have profiles with fraction millimeter dimensions?

We have standard profiles such as this type of tube with outer diameter of 60.3mm, used for example in railing. Why is it 60.3mm rather than exactly 60mm? In what application does the extra 0.3mm make ...
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2answers
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Find out the forces in members (as mentioned in the figure) of the truss by method of sections [closed]

I'm trying to find the forces in every member. But having a hard time resolving it. The Problem is to be solved by the Method of Sections of Truss.
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Working out location of a hydraulic jump

This is the question I am working on: And here is part of the working i don't understand: I don't understand the process of plotting the profile - the little crosses marked on the diagram, how do ...
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1answer
61 views

How to design an enclosure around the load cell (Beam type)?

Hardware and Electronics Used: Arduino UNO, HX711 ADC Load cell amplifier, Load Cell (2Kg); Currently, I am working on a project which requires me to put load cell along with the other circuitry in an ...
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54 views

How to guess direction of friction in any case

Here , in case of a death well situation as an example. Q How is direction of friction going to be opposite to mg or in upwards direction ? Why not: In case of like circular turning , direction of ...
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Is there any frame of reference in which we can neglect the gravitational force?

There is a laboratory in which there is a string tied to a bob on the earth.Consider the earth is perfect sphere ,rotates on its own axis in a circular path with uniform angular velocity. Main Q of ...
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How much energy is needed for the USA to only use desalinated water?

What amount of energy would it take to replace the entirety of America's water consumption with desalinated water? And how does it compare with the country's current energy generation capacity? By &...
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2answers
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How to construct rcc column footing on rock?

I am constructing my house on a rocky plot. Some of the columns will be placed over rocks and we were not able to dig deep in the rock. So, these column footings will be on the surface. Is it safe?
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Response time and time constant of Mercury thermometer

I searched to find differences between response time and time constant of a thermometer. So I found that those two are not same and we have to get 99.3% of the total step change to find response time ...
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1answer
35 views

Force required to vertically pull a post out of ground with various soil types

I am trying to determine the force required to vertically lift a typical traffic sign post (round, square and/or channel) out of the ground based on typical soil types at standard installation below ...
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2answers
50 views

Do PVC concrete joint water stops degrade over time? Or were they never installed correctly?

A UK subterranean reinforced concrete structure built in the late 1960s has experienced sustained water ingress over time as shown by the deposition of minerals of the walls: According to the ...
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1answer
107 views

PE exam: situations in which two question choices are close to my final answer: how to pick one?

Consider this question: I solve this eventual question and my answer is 7.29667: Among the question choices are 7 x 7 ft and <...
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2answers
60 views

How do I start determining the forces in the 3 bars?

For part A I have $\Delta$A + $\Delta$B = $\delta$. For part B I've tried summing forces at the joints but keep getting lost. Any help is appreciated my final is on Friday.
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How can steno's law of superposition be relevant in construction? [duplicate]

Steno's law of stratigraphic superposition states that younger layers of rock sit atop older layers. Meaning that the youngest stratum in a sedimentary sequence will be at the top and the oldest at ...
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1answer
53 views

How do engineers reduce vibration of system with multiple known natural frequencies? How do they design the isolation system for specific frequencies?

I have a system that is pretty much a chamber that needs to sit on the ground. I measured the transmissibility of the chamber vs the ground (output/chamber acceleration over input/ground acceleration) ...
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How would you build a road system that respected nature? [closed]

How would build a road system or transportation system that respected nature with the following constraints: No paved roads or less than 10% paved roads can’t use gasoline (oil) allow nature to ...
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37 views

Fixed end moments

If B is a roller or pinned, should the fixed end moment for AB be (wl2)/8?
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2answers
46 views

Stiffness factor of beam member

If I have a beam with the left end being "A" and it is fixed at that end and the right end being "B" with a roller support, would KAB=3EI/L??
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2answers
60 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 ...
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1answer
67 views

Questions about a controlled demolition video

I came across the following Youtube video which shows the controlled demolition of a chimney. https://www.youtube.com/watch?v=Sb62_QesDTw The construction of the chimney appears to be reinforced ...
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2answers
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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 ...
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1answer
49 views

FE Exam practice: “How many years until you're a millionaire?” [closed]

One of the early questions in the NCEES FE Industrial/Systems Exam studyguide has a solution that I can't decipher. The question is as follows: ...
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2answers
51 views

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

It is considered best practise to specify free draining backfill material (eg gravel) to be placed immediately behind a retaining wall. Supposedly, this alleviates hydrostatic pressure on the wall, ...
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4answers
370 views

Why does a beam in shear crack at 45 degrees?

Why does a beam in shear like in this picture crack at 45 degrees instead of vertically? This is called "Punching shear", and requires concrete reinforcement at an angle: Assuming that the ...
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1answer
42 views

Lintel construction technique in UK in 80s using blockwork

An issue has been raised when replacing windows that the blockwork inner leaf is missing a lintel. The hollow blocks have been in-filled with concrete which makes me believe that this is a ‘cast-it-...
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28 views

Conversion of orthographic projection to isometric projection [duplicate]

I'm new to engineering drawing, and I am having trouble drawing isometric projection from orthographic projections. Can someone give the steps/thought process behind this conversion? I can upload the ...
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1answer
54 views

Is it possible to use Plain Cement Concrete post for fencing?

I am in need of around 700-800 posts to fence my farm in a semi-arid area in TN state, India. In my place granite posts mined from quarries are normally used. It costs around Rs 300-400 per post(6-7ft)...
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1answer
31 views

What should be the relation between flange length and web thickness for an optimum I - beam?

While learning about I-beams I became curious to know if there is any relation between the flange length and web thickness of I-beams or if its arbitrary.
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3answers
80 views

how much force is required to drive a fence post 2ft into soil or sand using a hydraulic press?

I'm building a post driver for the farm and it got me thinking: what force is required to drive a 6ft(1.8 m) 4 inch (100 mm) post 2 ft into the ground? I'm wondering how different soils affect driving ...
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3answers
89 views

Axially loaded member with a spring / Mechanic of Materials

i've been struggling with this problem i made up. It is about a cylindrical copper member (diameter $d=20$ mm and length $L=250$ mm) with a spring (stiffness $k=166,5$ kN/mm) fixed on a wall, as the ...
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A mechanical system with coupled oscillators and dampers

I found here Coupled oscillators, the last one on this page, a system named by the author "Vehicle Suspension System". But I am not sure this modelizes a suspension for a vehicle. I am ...
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4answers
107 views

Deflection of a fixed-fixed pvc pipe under self weight

I would like to start by saying I am not an engineer, so I apologize if this question seems simpleminded. I am making a manual tarp reel from pvc pipe, and I am trying to decided whether to use ...
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1answer
52 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 ...
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1answer
140 views

What is a 'rocker slab'?

See below for an extract from a general arrangement drawing from the 1980s. It makes reference to a '9" rocker slab' which appears to be a slab supported by steel beams. Does anyone have any ...
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5answers
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Why are some public benches made with arm rests that waste so much space?

While watching a YouTube video today, I noticed this public/park bench somewhere in the USA: It looks strange to me the way the arm rests on each side are so far into the bench, wasting a rather ...
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2answers
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What's the name of the calculus used to make smooth transitions in roads?

So I'm not actually an engineer, I'm a novice computer programmer but I think in order to solve a problem I have I'm going to need some help from the world of engineering. I remember in high school ...
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28 views

Inspection chamber in sewage drain

For civil engineers, There is a high drain connection work is under progress in my location. Few days ago, a contractor visited my house and asked me to construct 2ftX2ft inspection chamber inside the ...

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