Questions tagged [building-physics]

The physics of buildings, specifically thermal conduction, convection, & radiation; heating and cooling; ventilation; transmission and management of water vapour & pollutants

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How did gothic church architects/builders properly scale up their models to full size churches?

In this video the author explains how ancient church builders used models to determine the proper shape and order of installation of architectural elements in gothic churches. From the little I know, ...
0 votes
3 answers
56 views

How to design safely collapsing buildings?

Background—Currently, buildings seem to be designed to be strong enough to not fall upon dangerous events, such as earthquakes. This makes them expensive, and out of the reach of poor places. Poor ...
0 votes
3 answers
110 views

How do I measure max oscillation of building using accelerometer?

For my school project, I am trying to measure the effect of a mass damper by changing the length of the string (that carries the mass), my setup is similar to the following video: https://youtu.be/...
3 votes
2 answers
298 views

Modeling rigid body dynamics: Trouble with equations, encountering nonsense answers

Hi, I am working on modeling a simple rigid body dynamic system through a certain range of motion. Here is the picture of the system. I am trying to solve the system for the variables $x_1'', y_1'', ...
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0 answers
54 views

How to make a galilean cannon with balls falling/rebounding straight

Here is what I mean by galilean cannon, simply letting balls fall, but hard to experiment though... First, I tried to drop 2 balls with my hands, but balls do not rebound straight and I get enormous ...
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0 answers
29 views

Washing machine in apartment

I live on a second floor of 4 story apartments building and I'm planning to change my old washer+dryer tower for a new one, however it is bigger and heavier. I'm worried that the weight could cause a ...
0 votes
2 answers
36 views

Can a buckling steel column fracture on multiple points?

When a column buckles, then yields, and finally fractures fractures, along the most stressed point, this will initially reduce the axial and bending strains along other points. The apparent conclusion ...
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1 answer
57 views

Doubt about Reynolds number formula

In fluid dynamics, when I have to compute Reynolds number, I was taught to differentiate between two cases: $$ 1)\space \frac{\rho\cdot v\cdot d}{\mu}$$ or $$2)\space \frac{v\cdot d}{\mu}$$ but, why ...
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How to compute the resistance of this metallic part (steel angle iron), for a joist fitted in an I-profile beam?

Let's say we have an oak joist (15 cm x 15 cm x 370 cm), which is "fitted" in the profile of an I-profile beam (height 140 mm, width 66 mm), and the surface where the joist is laid is too ...
0 votes
2 answers
107 views

how to find final temperature of a fluid in an heat exchanger?

I have to find final temperature of water in an heat exchanger. the heat exchanger must cool down air using water, meaning initial temperature of water must be cold, initial temperature of air is 298....
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33 views

Mechanism to even out force from linear motion

Not sure exactly how to explain this, but I am looking to use a threaded rod connected to a motor, to push and pull open a gate valve. My idea for this is to attach a nut to the handle of the pull/...
0 votes
2 answers
50 views

Advice needed on how to cool 50 ml liquid from 60 °C to 30 °C

In Short: I'm working on a project where we need to cool 50 ml of liquid from 60 °C to 30 °C or 20 °C. The liquid will be in a 150 ml copper container with an open top. Due to the lack of skills in ...
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0 answers
127 views

What design could fit this egg drop challenge?

My class is doing the egg drop challenge as a school project, but the rules are a little different than normal. First of all, the construction needs to contain a microbit connected to a battery pack ...
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2 answers
49 views

After how many days can concrete framework be removed?

After how many days can concrete framework be removed? Do admixture chemicals like superplasticizer or accelerating admixtures allow early removal of concrete framework?
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1 answer
2k views

What is the most efficient way to ionize air?

I have a project to convert wind energy directly to electrical energy with no moving parts. The wind will enter a reducing tunnel for concentration, then go through an unobstructing de-humidifier, ...
0 votes
1 answer
57 views

what speed must a bullet be fired at to turn into gas when hitting a steal plate

what speed must a bullet be fired at to turn into gas when hitting a steel plate. from watching this video on 9gag, i see that the bullet almost turns into liquid, what speed would it need to hit it ...
0 votes
3 answers
81 views

How deep do you have to check for problems underneath a building site?

When you're putting up a new building, you have to check the soil underneath for stability. How deep do you typically have to check? What's the extent of your "due diligence" when ensuring that a ...
1 vote
2 answers
43 views

Impact of decreasing weight from a part of body w.r.t tipping

If I decrease the weight from top portion of the body keeping all dimensions same, the center of mass shifts downwards, but does it makes it more stable against tipping from perpendicular forces ? ...
-2 votes
1 answer
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Would pyramid shape buildings prevent people from falling to their deaths? [closed]

If a building the shape of pyramids slops downwards, wouldn't it minimize the risk of fall from heights, whether intentionally or by accident (like fire/bomb scare), from a balcony or window opening? ...
1 vote
5 answers
588 views

Reinforced concrete by steel, poor durability, why?

I've been reading up about reinforced concrete, as it is one if not the cheapest way how to build (with some solid foundation). I found out that it actually has quite poor durability (50-100 years or ...
0 votes
2 answers
40 views

Who takes care of structural health monitoring of civil structures?

There are numerous studies about the possibility of structural health monitoring (SHM) of tall structures, like bridges, skyscrapers, water towers, wind turbines, where, for example, inclination or ...
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4 answers
61 views

Would a larger building more safely or smoothly ride the seismic waves of an earthquake?

If larger ships are less affected by ocean waves, and tend to ride smoothly through them, would that same principle influence the survivability of a larger building when weathering the seismic waves ...
1 vote
3 answers
138 views

Tensile Force on Line of Bolts

I'm presented with a problem requiring some analysis to determine if an antenna bracket mounted to a concrete blockwork wall is sufficiently strong enough to endure a wind load given the known surface ...
0 votes
4 answers
431 views

How are these bricks being supported?

My question is how can all of these bricks be supported by the thin columns on either side? How can there be that much empty space under all of the bricks that the arrow is going through? Looking at ...
2 votes
0 answers
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What would happen if the air conditioning failed in a skyscraper for an extended period?

I'm writing some fiction which involves the AC in a modern glass curtain skyscraper (50-80 floors?) in an American city failing for a period of weeks, maybe even for up to two months. Could anybody ...
5 votes
1 answer
90 views

What approaches are there for demolishing a structure and how is an approach chosen?

From my office on the 21st floor of a building in Vancouver, BC two parking garages in the process of being demolished are visible. A third is just out of view a few more blocks away. One of these ...
2 votes
1 answer
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Investigating the potential of generating energy from moving water in pipes on a water production site

I work on a water production site, we have a staggering amount of water flowing, much of which is just using gravity pressure and feeding into reservoir tanks. (flow on various sites ranges from 100 ...
0 votes
0 answers
28 views

Which will be stronger for securing a cantilever umbrella in a deck

I am securing a cantilever umbrella baseplate to a deck. The decking timber will be reinforced with a pine nog between the deck joists. The options that I have are to use 10mm stainless steel coach ...
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 ...
38 votes
2 answers
19k views

What is the purpose of these diversions in a natural gas line?

The campus where I work has a long covered walkway (~.5 mile) which has several labeled pipes running under the roof (chilled water, fuel oil, air...). All of the pipes run dead straight except for ...
-1 votes
1 answer
83 views

calculating energy usage with measuring the temperature

I am an electrical engineer working on a project. My goal of this project is to make an IoT solution where I continuously measure the temperature of room in a building. I want to calculate the amount ...
0 votes
1 answer
47 views

Why did they move ancient Egyptian temples to prevent them from water damage instead of encircling them with a dam?

Specifically I'm talking about Abu Simbel temple and Philae temple. Which are close to a reservoir created by Aswan dam. It seems to me easier to build a dam than to move a temple.
-1 votes
1 answer
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Is it just surface area alone that causes bridges to freeze?

Scenario: Object 1, a bridge freezes over do to the surface area exposed to the below freezing air. Object 2 has the same surface area exposed to the same air, but its base sits on the ground that is ...
0 votes
1 answer
375 views

Could Tesla have REALLY shaken a building with a little oscillator?

I came across this story while reading about Nikola Tesla ground-power scheme. Supposedly, he created a little oscillator that could be plugged into the ground, tuned to the right (resonant) frequency,...
1 vote
3 answers
146 views

Can temperature gradient keep concrete wall below 100% RH in 100% RH atmosphere?

Consider a high and wide concrete wall of say 30 cm thickness, covered with a sheet of vapor barrier on one side, and a sheet of say 30 cm thick and effective insulation on the other side. The vapor ...
-1 votes
2 answers
410 views

Why are/were sewers made large enough for somebody to walk down in there?

Today, I have been reading a lot about sewer systems on Wikipedia, in the hope that I would find information or at least photos showing what I think of as sewers, namely somewhere under the streets in ...
2 votes
0 answers
43 views

One dimensional U-Factor Calculation - How to determine indoor / outdoor film resistances

Can someone clarify the ASHRAE Fundamental 2017 (SI Units) (See Below) Indoor and Outdoor film resistances. The manual states that it comes from Table 3 and in the description of table 3 it states &...
2 votes
0 answers
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Sun light illumination on a lower floor vs high building closely

there is an investor that wants to build very close to our building. In case we agree, the buildings will stand like on the pictures below, 3 meters apart from each other. I tried to draw them in ...
0 votes
1 answer
217 views

What does Leonardo da Vinci mean in his statement on arches?

I was recently reading some of Leonardo da Vinci's notes on architecture. One passage on arches states: An Experiment to show that a weight placed on an arch does not discharge itself entirely on ...
-1 votes
3 answers
380 views

can ceramic be used as a building material?

From what I read, concrete has much lower compressive strength than ceramics. So why aren't we using ceramics to build? Is it because ceramic failure is difficult to predict? Because it's hard to ...
2 votes
0 answers
48 views

Increase in target emission rate (TER) when using a air source heat pump (ASHP) in standard assessment procedure (SAP) calculation

I am running a SAP calculation on a proposed building which will be utilising a 8.5 kW ASHP for space and water heating. I am also running a comparative analysis against a mains gas boiler to show the ...
6 votes
2 answers
63 views

Is a single large impact better than several small impacts for breaking ice

I'm designing a device that uses impact to remove ice from sidewalks. I have a question about how to best design the impact mechanism. I can design it to deliver several light impacts or fewer harder ...
3 votes
0 answers
276 views

What is the minimum height of a chimney needed in a camper?

Like a lot of people nowadays, I'm fitting a log fire into the back of a camper van but can't find the minimum height above the roof for the chimney. Ideally, it should be as low as possible for ...
0 votes
1 answer
112 views

Do concealed door closers exacerbate wear on a door's hinges?

Not being of an engineering background, I was first inclined to think that a door closer would reduce horizontal load on all hinges and not contribute any support in the vertical dimension. However, ...
1 vote
1 answer
156 views

Inertial Forces while analysing forces on a Piston in a Slider - Crank Mechanism?

I get that we are analysing the Piston in a non-inertial frame of reference, but the point of my question is that according to D'Alembert's Principle, whenever an inertial force comes in the line of ...
1 vote
1 answer
38 views

Looking for something to reflect ultraviolet light at extremely low wavelengths

I have been working on a product that involves the reflection of low wavelengths of UV light (200-250nm). However, I have not come across many materials that are able to do so and the high-...
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 ...
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 ...
1 vote
0 answers
25 views

Heat storage mass vs. AIR in an ICF house

If we would want to build a family house (ICF) regarding operational costs, should we leave the insulation on the inside, or should we remove it from the inside? If we would remove it, the walls ...
1 vote
1 answer
103 views

how would one calculate the % of heat not absorbed by a heat sink?

I'm planning on building a plant growth chamber inside a sealed/insulated 55 g rain barrel, and I'm trying to figure out how much of the heat from my lights will enter the chamber, and how much ...