Monday, August 31, 2020

RINSING OFF SOAP WITH SOFT WATER - Why Is It Harder to Rinse Off Soap With Soft Water? - Rinsing in soft water may leave you feeling a little slippery and soapy, even after a thorough rinsing. Why? The answer lies in understanding the chemistry of soft water and soap. Hard water contains calcium and magnesium ions. Water softeners remove those ions by exchanging them for sodium or potassium ions. Two factors contribute to that slippery-when-wet feeling you get after soaping up with soft water. First, soap lathers better in soft water than in hard water, so it's easy to use too much. The more dissolved soap there is, the more water you need to rinse it away. Second, the ions in softened water lessen its ability to stick to the soap molecules, making it more difficult to rinse the cleanser off your body. The reaction between a triglyceride molecule (fat) and sodium hydroxide (lye) to make soap yields a molecule of glycerol with three ionically bonded molecules of sodium stearate (the soap part of soap). This sodium salt will give up the sodium ion to water, while the stearate ion will precipitate out of solution if it comes into contact with an ion that binds it more strongly than sodium (such as the magnesium or calcium in hard water). The magnesium stearate or calcium stearate is a waxy solid that you know as soap scum. It can form a ring in your tub, but it rinses off your body. Soap would rather stick to you than get rinsed away in soft water.

Washing Hands with Soap and Water
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Rinsing Off Soap With Soft Water
Why Is It Harder to Rinse Off Soap With Soft Water?
By Anne Marie Helmenstine, Ph.D.


Do you have hard water?
If you do, you may have a water softener to help protect your plumbing from scale buildup, prevent soap scum, and lessen the amount of soap and detergent needed for cleaning.
You've probably heard that cleaners work better in soft water than in hard water, but does that mean you will feel cleaner if you bathe in soft water?
Actually, no.
Rinsing in soft water may leave you feeling a little slippery and soapy, even after a thorough rinsing.
Why? The answer lies in understanding the chemistry of soft water and soap.
The Hard Facts of Hard Water
Hard water contains calcium and magnesium ions. Water softeners remove those ions by exchanging them for sodium or potassium ions.
Two factors contribute to that slippery-when-wet feeling you get after soaping up with soft water.
First, soap lathers better in soft water than in hard water, so it's easy to use too much.
The more dissolved soap there is, the more water you need to rinse it away.
Second, the ions in softened water lessen its ability to stick to the soap molecules, making it more difficult to rinse the cleanser off your body.
Chemical Reaction
The reaction between a triglyceride molecule (fat) and sodium hydroxide (lye) to make soap yields a molecule of glycerol with three ionically bonded molecules of sodium stearate (the soap part of soap). 
This sodium salt will give up the sodium ion to water, while the stearate ion will precipitate out of solution if it comes into contact with an ion that binds it more strongly than sodium (such as the magnesium or calcium in hard water).
The magnesium stearate or calcium stearate is a waxy solid that you know as soap scum.
It can form a ring in your tub, but it rinses off your body.
The sodium or potassium in soft water makes it much more unfavorable for the sodium stearate to give up its sodium ion so that it can form an insoluble compound and get rinsed away.
Instead, the stearate clings to the slightly charged surface of your skin.
Essentially, soap would rather stick to you than get rinsed away in soft water.
Addressing the Problem
There are a few ways you can address the problem:
You can use less soap, try a synthetic liquid body wash (synthetic detergent or syndet), or rinse with naturally soft water or rainwater, which probably won't contain elevated levels of sodium or potassium.

Anne Marie Helmenstine, Ph.D.
Chemistry Expert
Education
Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
B.A., Physics and Mathematics, Hastings College
Introduction
Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.
Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.
ThoughtCo and About Education chemistry expert since 2001.
Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.
Experience
Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.
In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor. 
Education
Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.
ThoughtCo and Dotdash
ThoughtCo is a premier reference site focusing on expert-created education content. We are one of the top-10 information sites in the world as rated by comScore, a leading Internet measurement company. Every month, more than 13 million readers seek answers to their questions on ThoughtCo.
For more than 20 years, Dotdash brands have been helping people find answers, solve problems, and get inspired. We are one of the top-20 largest content publishers on the Internet according to comScore, and reach more than 30% of the U.S. population monthly. Our brands collectively have won more than 20 industry awards in the last year alone, and recently Dotdash was named Publisher of the Year by Digiday, a leading industry publication.
Washing Hands with Soap and Water

Sunday, August 30, 2020

ASPARAGUS - In ancient times, asparagus was renowned as an aphrodisiac, and maybe for good reason. This succulent, savory vegetable contains a stimulating blend of nutrients that help boost energy, cleanse the urinary tract and neutralize excess ammonia, which can cause fatigue and sexual disinterest. High in vitamin K and folate (vitamin B9), asparagus is extremely well balanced, even among nutrient-rich vegetables. The vegetable contains the amino acid asparagine, which is important in the development and function of the brain. It also contains chromium, a trace mineral that helps insulin do its job transporting glucose. It's also especially rich in glutathione, a detoxifying compound that can help destroy carcinogens. For this reason, asparagus may help fight or protect against certain cancers, including bone, breast, lung and colon cancers. Asparagus is extremely low in calories at about 20 per serving (five spears), has no fat, and is low in sodium. It can be eaten raw or cooked; however, cooking times affect health benefits. And the vegetable's high level of B vitamins helps regulate the amino acid homocysteine, too much of which can be a serious risk factor in heart disease. Asparagus also has soluble fiber which lowers the risk of heart disease, and the amino acid asparagine helps flush your body of excess salt. Asparagus has excellent anti-inflammatory effects and high levels of antioxidants, both of which may help reduce the risk of heart disease.

10 Asparagus Health Benefits - And Health Risks - Explained
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Asparagus
Pictures of Things That Can Affect the Smell of Your Pee
Health Benefits, Risks (Stinky Pee) & Nutrition Facts
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asparagus, nutrition, healthAsparagus can act as a natural diuretic - this can help rid the body of excess salt and fluid, making it especially good for people suffering from edema and high blood pressure. It also helps flush out toxins in kidneys and prevent kidney stones. Asparagus is known to help stabilize digestion due to the high amount of fiber and protein that it contains - both help move food through the gut and provide relief from discomfort during digestion. Asparagus contains inulin, a unique dietary fiber associated with improved digestion. Inulin is a prebiotic; it does not get broken down and digested until it reaches the large intestine. There, it nurtures bacteria known to improve nutrient absorption, decrease allergies and reduce the risk of colon cancer.
By Jessie Szalay - Live Science Contributor



In ancient times, asparagus was renowned as an aphrodisiac, and maybe for good reason.
Health benefits of asparagus | Like a miracle | Healthy Recipe SeaThis succulent, savory vegetable contains a stimulating blend of nutrients that help boost energy, cleanse the urinary tract and neutralize excess ammonia, which can cause fatigue and sexual disinterest.
High in vitamin K and folate (vitamin B9), asparagus is extremely well balanced, even among nutrient-rich vegetables.
"Asparagus is high in anti-inflammatory nutrients," said San Diego-based nutritionist Laura Flores.
It also "provides a wide variety of antioxidant nutrients, including vitamin C, beta-carotene, vitamin E, and the minerals zinc, manganese and selenium."
Furthermore, the vegetable contains the amino acid asparagine, which is important in the development and function of the brain, according to a study published in 2013 in the journal Neuron.
It also contains chromium, a trace mineral that helps insulin do its job transporting glucose.
It's also especially rich in glutathione, a detoxifying compound that can help destroy carcinogens.
For this reason, asparagus may help fight or protect against certain cancers, including bone, breast, lung and colon cancers.
Benefits of Asparagus And Its Side Effects | LybrateAsparagus is extremely low in calories at about 20 per serving (five spears), has no fat, and is low in sodium.
It can be eaten raw or cooked; however, cooking times affect health benefits.
A 2011 study published in Food Chemistry examined blanching (cooking asparagus briefly in boiling water) and saw a marked difference in the asparagus depending on how long the vegetable was submerged.
In general, the longer the asparagus was blanched, the more nutrients it lost, though cooking it for too short a time resulted in hard stalks.
Furthermore, the tip, middle and bottom sections of the spears had different sensitivities to blanching times, with the tip being the most likely to lose nutrients quickly.
The authors of the study therefore recommend blanching different segments of asparagus for different lengths of time.
Health benefits
Heart health
Asparagus is good for your ticker in a variety of ways. Flores noted, "Asparagus is extremely high in vitamin K, which helps blood clot."
Healthy Lifestyle – reiimmune® the Hydrobiotic™And the vegetable's high level of B vitamins helps regulate the amino acid homocysteine, too much of which can be a serious risk factor in heart disease, according to Harvard University School of Public Health.
Asparagus also has more than 1 gram of soluble fiber per cup, which lowers the risk of heart disease, and the amino acid asparagine helps flush your body of excess salt.
Lastly, asparagus has excellent anti-inflammatory effects and high levels of antioxidants, both of which may help reduce the risk of heart disease.
Regulating blood sugar
Inimitably Asparagus - The Permaculture Research Institute
The Mayo Clinic notes that vitamin B6 may affect blood sugar levels and advises caution for people who have diabetes or low blood sugar.
However, those with healthy levels can benefit from asparagus's ability to regulate it.
Lowering the risk of type 2 diabetes
As with heart disease, risk of type 2 diabetes increases with excessive inflammation and oxidative stress.
Therefore, asparagus' impressive anti-inflammatory properties and high levels of antioxidants make it a good preventive food.
A 2011 study published in the British Journal of Nutrition also suggested that asparagus' ability to improve insulin secretion and improve beta-cell function also helps lower the risk of type 2 diabetes.
Beta cells are unique cells in the pancreas that produce, store and release insulin.
Anti-aging benefits
That's What She Fed: Asparagus, pee and your noseThe antioxidant glutathione is thought to slow the aging process, according to a 1998 article in The Lancet journal.
And the folate that asparagus provides works with B12 to prevent cognitive decline.
A Tufts University study found that older adults with healthy levels of folate and B12 performed better during a test of response speed and mental flexibility than those with lower levels of folate and B12.
Skin
Yet another amazing thing about the antioxidant glutathione: it helps protect the skin from sun damage and pollution.
A small 2014 study published in Clinical, Cosmetic, and Investigational Dermatology studied healthy adult women ages 30-50 who applied a glutathione lotion to half their faces and a placebo lotion to the other half for 10 weeks.
The glutathione side saw increased moisture, suppressed wrinkle formation and smoother skin. It is unknown if eating glutathione-rich foods like asparagus would produce a similar effect.
Keeping you cleansed and preventing kidney stones
Asparagus can act as a natural diuretic, according to a 2010 study published in the West Indian Medical Journal.
Health Benefits of Asparagus, Nutritional Facts And Consumption TipsThis can help rid the body of excess salt and fluid, making it especially good for people suffering from edema and high blood pressure.
It also helps flush out toxins in kidneys and prevent kidney stones.
On the other hand, the National Institutes of Health recommends that people who are suffering from uric acid kidney stones should avoid asparagus.
Pregnancy health
Flores noted asparagus' significant amount of folate, which she said "is important for women of childbearing age to consume daily."
Folate can decrease the risk of neural-tube defects in fetuses, so it is essential that mothers-to-be get enough of it.
Digestive health
"Asparagus is known to help stabilize digestion due to the high amount of fiber and protein that it contains," said Flores.
"Both help move food through the gut and provide relief from discomfort during digestion."
According to The Ohio State University, asparagus contains inulin, a unique dietary fiber associated with improved digestion.
Inulin is a prebiotic; it does not get broken down and digested until it reaches the large intestine.
There, it nurtures bacteria known to improve nutrient absorption, decrease allergies and reduce the risk of colon cancer.
Immune system health and cancer risk
Antioxidants and anti-inflammatories, which are found in great quantities in asparagus, are typically associated with decreased risk of cancers.
A 2016 review in the journal Nutrients stated that polysaccharides (carbohydrate molecules) found in asparagus helped inhibit dangerous liver cancer cell proliferation in animal studies.
When injected with anti-cancer drugs directly into the tumor, scientists saw "markedly suppressed liver tumor growth as well as prolonged survival time … with little toxicity."
A group of phytonutrients called saponins are found in high qualities in asparagus.
They have both fat-soluble and water-soluble components, meaning they can affect the body in more ways than some other phytonutrients can.
They are known for their effects on cell membranes and immune response.
Today, several animal studies have been done to learn more about how saponins can inhibit production inflammatory molecules and promote white blood cell activity.
One such study, published in Biomedicine and Pharmacology in 2017, proposes that saponins from asparagus might be a helpful component in preventing secondary tumor formation.
The study looked at the effect of saponins from asparagus being injected into mice for 56 days and saw an improvement in cellular immunity without the high allergic reactions typical in drugs used to prevent secondary tumors.
Risks of eating asparagus
"There are no life-threatening side effects of eating too much asparagus," said Flores, "but there may be some uncomfortable side effects such as gas, and a noticeable smell to the urine."
It is also possible to have an asparagus allergy, in which case you should not eat it, she said.
People who are allergic to other members of the lily family, such as onions, garlic, and chives, are more likely to be allergic to asparagus.
Symptoms include a runny nose, hives, trouble breathing, and puffiness or swelling around the mouth and lips.
Why does asparagus make urine smell?
According to Smithsonian magazine, asparagus is the only food to contain the chemical asparagusic acid.
When this aptly named chemical is digested, it breaks down into sulfur-containing compounds, which have a strong, unpleasant scent.
They are also volatile, which means that they can vaporize and enter the air and your nose.
Asparaguisic acid is not volatile, so asparagus itself doesn't smell.
Genes for Smelling Asparagus Metabolites Determine Urine Luck - Scientific  AmericanWhat's weirder than a veggie causing stinky pee? The fact that not everyone can smell it.
Scientists aren't entirely sure why this is. Most evidence seems to suggest that not everyone can smell the odor, though some scientists think that not everyone produces it.
In 2016, The BMJ medical journal published a study in which researchers examined data from The Nurses' Health Study, a large-scale study involving nearly 7,000 participants of European descent, to help determine if there is a genetic basis for smelling asparagusic acid.
More than half of the participants could not smell it and researchers found that genetic variations near olfactory receptor genes was associated with the ability to detect the smell.
The researchers suggested treatments could potentially be created to turn smellers into non-smellers and thereby increase the potential for eating healthy asparagus.
Whether you can smell it or not, there are no harmful effects to producing, or smelling, the odor in urine.
Asparagus facts
According to the Michigan Asparagus Advisory Board:
Asparagus comes in three varieties: American and British, which is green; French, which is purple; and Spanish and Dutch, which is white.
Asparagus was first cultivated about 2,500 years ago in Greece.
"Asparagus" is a Greek word, meaning stalk or shoot.
The Greeks believed asparagus was an herbal medicine that would cure toothaches and prevent bee stings, among other things.
Galen, a second-century physician, described asparagus as "cleansing and healing." Claims for medicinal benefits of asparagus persist to this day.
The Romans became great lovers of asparagus, and grew it in high-walled courtyards. In their conquests, they spread it to the Gauls, Germans, Britons and from there, the rest of the world.
The top asparagus-producing states are California, Washington and Michigan.
Asparagus spears grow from a crown that is planted about a foot deep in sandy soils.
Health Benefits of Asparagus, Nutritional Facts And Consumption TipsUnder ideal conditions, an asparagus spear can grow 10 inches in 24 hours.
Each crown will send spears up for about 6-7 weeks during the spring and early summer.
The outdoor temperature determines how much time will be between each picking.
Early in the season, there may be four or five days between pickings and as the days and nights get warmer, a particular field may have to be picked every 24 hours.
After harvesting is done, the spears grow into ferns, which produce red berries and the food and nutrients necessary for a healthy and productive crop the next season.
An asparagus planting is usually not harvested for the first three years after the crowns are planted, allowing the crown to develop a strong fibrous root system.
A well-cared-for asparagus planting will generally produce for about 15 years without being replanted.
The larger the diameter, the better the quality!

Jessie Szalay is a contributing writer for LiveScience and nonfiction editor of So to Speak Journal. Her work has appeared in The Jewish Daily Forward, Waccamaw Literary Journal, and National Geographic Traveler--Personal Explorer, among other places. She lives in Washington, DC and is working on a book of personal narrative and social inquiry regarding interfaith issues and non-LDS identity within Utah.
Grow it yourself: Asparagus | CANNA Gardening USA
Winter Asparagus Soup | Banyan Botanicals

Saturday, August 29, 2020

OLEANDRIN A POSSIBLE TREATMENT FOR COVID-19 - What is oleandrin, the compound touted as a possible COVID-19 treatment? Scientists warn that the botanical natural product is unproven and could have lethal side effects. Recent news that US President Donald J. Trump has expressed interest in researchers investigating oleandrin as a possible COVID-19 treatment has scientists raising alarms that the compound is unproven and has dangerous, potentially lethal side effects. So what is oleandrin and what do we know about it? Oleandrin is a sugar-containing compound found in Nerium oleander, a shrub that’s popular for landscaping in the southern US and elsewhere. The plant is poisonous, causing nausea, vomiting, irregular heartbeat, and in some cases death when consumed. Oleandrin accounts for much of N. oleander’s toxicity, and it’s in every part of the plant from root to flower. Animals and people have died from eating the plant. Reports of poisonings resulting from the use of twigs from the plants to roast food date back to the 1800s. Oleandrin inhibits the action of sodium and potassium pumps in heart tissue, which are involved in the electrical signaling responsible for heart-muscle contractions. Sodium and potassium pumps also control the water balance in cells, which is why people with oleandrin poisoning experience nausea and diarrhea, adds Justin Brower, a forensic toxicologist.

Beware Oleandrin, It is a Deadly Cardiac Poison, Not a COVID-19 Cure – The  Skeptical Cardiologist
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Notes from the Kakistocracy: Miracle cure or deadly toxin? | BlueNC
Oleandrin a possible treatment for COVID-19
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New Poison For You: Oleander Cure Covid - Oleandrin Supplement - Oleander  Trump - Oleandrin Trump - YouTubeWhat is oleandrin, the compound touted as a possible COVID-19 treatment?
Scientists warn that the botanical natural product is unproven and could have lethal side effects
by Bethany Halford



Oleandrin is not a coronavirus cure, Trump. It's a plant poisonRecent news that US President Donald J. Trump has expressed interest in researchers investigating oleandrin as a possible COVID-19 treatment has scientists raising alarms that the compound is unproven and has dangerous, potentially lethal side effects.
So what is oleandrin and what do we know about it?
Oleandrin is a sugar-containing compound found in Nerium oleander, a shrub that’s popular for landscaping in the southern US and elsewhere.
The plant is poisonous, causing nausea, vomiting, irregular heartbeat, and in some cases death when consumed.
“Most people who have grown up around this plant have been told since childhood, ‘Don’t eat this plant. It will kill you,’” says Cassandra L. Quave, a medical ethnobotanist at Emory University.
Oleandrin accounts for much of N. oleander’s toxicity, and it’s in every part of the plant from root to flower.
Oleandrin won't cure coronavirus Flipboard에서 Popular Science님Animals and people have died from eating the plant.
Reports of poisonings resulting from the use of twigs from the plants to roast food date back to the 1800s, although more recent tales about deadly feasts of hot dogs roasted on oleander twigs have been debunked.
A case report from 2006 details how two people suffered oleandrin poisoning after dining on homemade snail stew (J. Anal. Toxicol. 2006, DOI: 10.1093/jat/30.9.683).
The snails had been found near N. oleander plants in their garden and analysis of the frozen leftover snails revealed they contained oleandrin, which the snails probably took in when their slime mingled with the plant’s juices.
Oleandrin photos, royalty-free images, graphics, vectors & videos | Adobe  StockOleandrin inhibits the action of sodium and potassium pumps in heart tissue, which are involved in the electrical signaling responsible for heart-muscle contractions.
Sodium and potassium pumps also control the water balance in cells, which is why people with oleandrin poisoning experience nausea and diarrhea, adds Justin Brower, a forensic toxicologist who writes the Nature’s Poisons blog about toxic natural products and is working on a book by the same name.
Quave and Brower point out that oleandrin is structurally similar to digoxin, a cardiac glycoside used to treat various cardiac conditions.
But they note that digoxin has a narrow therapeutic window — the dose required for it to be an effective treatment is close to the dose that makes it toxic.
oleandrin Archives - Kara Fitzgerald ND Naturopathic DoctorThe US Food and Drug Administration has not approved oleandrin or experimental N. oleander extracts, such as Anvirzel or PBI-05204, for the treatment of any disease.
Oleandrin and N. oleander extracts have been studied as potential treatments for cancer and as antivirals.
In July, a preprint published on bioRxiv claimed that oleandrin can stop SARS-CoV-2, the virus that causes COVID-19, from replicating in cells in a test tube (2020, DOI: 10.1101/2020.07.15.203489).
The paper has not yet been vetted by other scientists.
Robert Harrod, a virologist at Southern Methodist University, has studied oleandrin’s ability to block human T-cell leukemia virus, type 1, a retrovirus that causes a fatal blood cancer, from spreading to other cells in test tubes (J. Antivir. Antiretrovir. 2019, DOI: 10.35248/1948-5964.19.11.184).
He says oleandrin probably does this by blocking cells from binding to the virus’s glycoprotein spike — a process he says could be general for envelope viruses, including SARS-CoV-2.
He notes that there’s a lot more research needed to go from the preprint to giving oleandrin to people, including tests in human cells, animal models, and early clinical trials.
“Even if it does make it into treatment of coronavirus as a therapeutic, this is going to have to be monitored very closely by doctors,” Harrod says.
“It is a very dangerous compound.”
Even so, he’s not willing to dismiss the idea.
“We should wait and look at the data before making a decision,” he says.
Because of the recent hype around oleandrin, Emory’s Quave worries that people might try to self-treat with N. oleander.
“Don’t consume or smoke this plant or consume any oleandrin,” she warns.

Bethany Halford, Senior Correspondent
Bethany Halford
Phone: 202-579-4133
E-Mail: b_halford@acs.org
Twitter: @beth_halford
Areas of coverage: Chemistry in general, particularly organic chemistry, medicinal chemistry, nanotechnology, and materials science. Also, as Newscripts editor, loves a quirky science story.
Once upon a time Bethany was a synthetic organic chemist, churning out new molecules. She used to tell people she was a sculptor on a very small scale. Now she sculpts stories. She works in her office and various coffee shops in the Boston area.
What You Need to Know About Oleandrin, the Unproven COVID 'Cure'COVID-19: Doctors refute claim that oleandrin can be a cure for coronavirus  - EconoTimesOleandrin, touted as COVID-19 cure, has no scientific support | NestiaCan oleandrin treat COVID-19? - CGTN

Thursday, August 27, 2020

PRE-ENGINEERED BUILDINGS - Pre-engineered buildings are factory-built buildings of steel that are shipped to site and bolted together. What distinguishes them from other buildings is that the contractor also designs the building - a practice called design & build. This style of construction is ideally suited to industrial buildings and warehouses; it is cheap, very fast to erect, and can also be dismantled and moved to another site - more on that later. These structures are sometimes called 'metal boxes' or 'tin sheds' by laymen - they are essentially rectangular boxes enclosed in a skin of corrugated metal sheeting. Great speed is achieved because while the foundations and floor slab are being constructed, the beams and columns - the structural system - are being fabricated in the factory. Once the foundations and floor are done, the columns are shipped to the site, lifted into place by cranes, and bolted together. The structural system of pre-engineered steel buildings give it its speed and flexibility. This system consists of factory-fabricated and factory-painted steel column and beam segments that are simply bolted together at site. The columns and beams are custom-fabricated I-section members that have an end plate with holes for bolting at both ends. These are made by cutting steel plates of the desired thickness, and welding them together to make I sections.


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Pre-Engineered Buildings
understandconstruction.com




Pre-engineered buildings are factory-built buildings of steel that are shipped to site and bolted together.
What distinguishes them from other buildings is that the contractor also designs the building - a practice called design & build.
This style of construction is ideally suited to industrial buildings and warehouses; it is cheap, very fast to erect, and can also be dismantled and moved to another site - more on that later.
These structures are sometimes called 'metal boxes' or 'tin sheds' by laymen - they are essentially rectangular boxes enclosed in a skin of corrugated metal sheeting. 
This pre-engineered industrial building, designed by one of the authors of understandconstruction.com,
 has polycabonate strips in the roof to allow for uniform natural lighting. Ten foot (3m) high concrete
block walls on the periphery contain windows and provide security; above that,  the only walling
material is a thin corrugated metal sheet.
Great speed is achieved because while the foundations and floor slab are being constructed, the beams and columns - the structural system - are being fabricated in the factory.
Once the foundations and floor are done, the columns are shipped to the site, lifted into place by cranes, and bolted together.
STRUCTURAL SYSTEMS
The structural system of pre-engineered steel buildings give it its speed and flexibility.
This system consists of factory-fabricated and factory-painted steel column and beam segments that are simply bolted together at site.
The columns and beams are custom-fabricated I-section members that have an end plate with holes for bolting at both ends.
These are made by cutting steel plates of the desired thickness, and welding them together to make I sections.
The cutting and welding is done by industrial robots for speed and accuracy; operators will simply feed a CAD drawing of the beams into the machines, and they do the rest.
This production line style of work makes for great speed and consistency in fabrication.
Pre-engineered building before the roof skin has been installed. Note that the shape  of the
beams follows the forces in them; the beams are deeper where the forces are greater.
The shape of the beams can be tailored to optimum structural efficiency: they are deeper where the forces are greater, and shallow where they are not.
This is one form of construction in which the structures are designed to carry exactly the loads envisioned, and no more.
ERECTION
Each piece of the system is very much alike - an I section with end plates for bolting.
The painted steel sections are lifted into place by crane, and then bolted together by construction workers who have climbed to the appropriate position.
In large buildings, construction can start with two cranes working inwards from both ends; as they come together, one crane is removed and the other finishes the job.
Usually, each connection calls for six to twenty bolts to be installed. Bolts are to be tightened to exactly the right amount of torque using a torque wrench.
FOUNDATIONS AND FLOOR SLAB
The foundations for pre-engineered metal buildings are made with conventional concrete systems, usually open foundations.
Since these structures are usually quite large, they attract a fair amount of wind forces.
Wind can cause a net upwards force on a building, called uplift.
Since these structures are very light (they can weigh as little as 50 kg per square meter, excluding the foundations and floor slab), the foundations are designed to firmly anchor the structures to the ground, preventing them from being blown away by the wind.
The floor system for industrial and storage buildings is usually a thick (about 8" to 12" / 200 to 300mm) concrete grade slab that rests directly on the prepared earth beneath it.
The concrete can be topped with a thin, abrasion resistant smooth coating called an epoxy floor or polyurethane floor if desired.
CLADDING AND ROOFING - THE BUILDING ENVELOPE
The most economical cladding for these structures is light corrugated metal sheeting, on both the roof and the external walls.
These steel sheets, barely 0.5mm thick, are coated with an aluminum-zinc alloy for corrosion protection on both sides, and come with an attractive, durable paint finish on the outside.
These sheets are installed over a grid of purlins, a steel member that rests on the main structural frame and supports the roofing material.
In pre-engineered buildings, cold formed Z sections are the member of choice for purlins.
Before installing the sheets, contractors will install layers of insulation and vapor barriers.
Rolls of glass wool or mineral wool are the most common type of insulation for such buildings.
Since there is no inner wall over which to fix these layers, a layer of galvanized chicken wire mesh is first laid over the purlins.
Over this, the insulation and vapor barriers are laid, and then the corrugated sheets are laid.
The sheets are fixed with self tapping screws that run through the sheets and layers of insulation directly into the purlins.
The purlins, chicken mesh and insulation are thus visible from below, and can be left as such or covered with a false ceiling.
Polycarbonate skylights can be installed in the roof sheeting to create natural lighting.
It is common for industrial buildings to have a masonry wall upto a height of 10 or 15 feet (3 to 5m).
This allows doors and windows to be easily fitted, and provides security.
This wall can be built behind the metal sheeting, making it invisible from the outside.

 This is a site that explains the art and science of building construction in great clarity and detail.  Our goal is to make you understand concepts in building construction.
Written by architects and engineers, the content on the site is actually a result of accumulated years of work experience at building construction sites and design offices.  This expert knowledge of building construction is not available in textbooks!
We also take great pains to ensure that our quality of writing is of a high standard.  We aim to take complicated situations and make them simple and clear, as well as to provide content that is interesting to industry experts and newcomers alike.  Do let us know where we succeed - and where we fail - in this task.