# 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, ...
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 ...
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/...
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'', ...
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 ...
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 ...
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 ...
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 ...
24 views

### 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 ...
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....
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/...
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 ...
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 ...
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?
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, ...
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 ...
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
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 ? ...
74 views

### 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
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 ...
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 ...
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
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 ...
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 ...
84 views

### 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 ...
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 ...
68 views

### 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 ...
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 ...
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 ...
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 ...
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 ...
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.
36 views

### 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 ...
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
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 ...
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 ...
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 &...
18 views

### 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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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
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
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-...
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 ...
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