science

Porch collapse

Porch collapse is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Porch collapse rather than just read about it. In short: Porch collapse or balcony collapse is a phenomenon typically associated with older or poorly constructed multi-story apartment buildings that have wooden porch extensions on the front or rear of the building. The collapses have a number of causes, including overloading due to excessive weight from overoccupancy (too many people).

Key takeaways

Porch collapse belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Porch collapse to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Porch collapse from memory before moving on to harder problems.

Reference excerpt

Porch collapse or balcony collapse is a phenomenon typically associated with older or poorly constructed multi-story apartment buildings that have wooden porch extensions on the front or rear of the building. The collapses have a number of causes, including overloading due to excessive weight from overoccupancy (too many people). Overoccupancy can result from guests filling a porch at a party, from people seeking cooler breezes during a heat wave, or from people filling a porch while seeking shelter from the rain. It may be from the weight of furniture/appliances, wading pools, or air conditioner compressors. After years of rain and snow, it may be from rotted wood, soil subsidence under the porch foundation, rust of nails and fasteners, and not being built to specifications required by modern-day building codes. Many older porches were built before codes required them to be able to support a legally mandated load of so many pounds per square foot or metre, and porches are often not as sturdily built as interior structures. The phenomenon is associated with older or poorly constructed multistory apartment buildings with wooden porches. Architect Stanley Tigerman said that in New York City one finds steel fire escapes, but in Chicago, the distance to alleys behind multistory brick buildings encouraged the construction of wooden multistorey porches. While not an everyday occurrence, collapses happen often enough in Chicago that city building inspectors make a point of checking porches when making inspections. People have been killed and injured by collapses of wooden porches in other cities as well. A Chicago porch collapse during a get-together in the Lincoln Park neighborhood in 2003 killed 13 people. The weight of approximately 70 people caused the recently renovated porch of the 1890s vintage building to fail. The disaster inspired a 2005 episode of the ER television show. In June 2008, a third-story balcony collapsed in Ottawa, injuring six persons.

Deck collapse A related hazard is the collapse of decks built as outdoor extensions of single-family homes. When decks became a popular feature, construction practice did not keep up with the new fashion, resulting in many decks that were simply nailed to the side of their houses. The inherently weak connections were prone to failure, resulting in collapse with injuries and occasional death. In recent years building codes have been re-written to require direct structural connection to the adjoining structure, as well as cross-bracing to withstand sway.

High-rise apartments High-rise apartment buildings are typically constructed from reinforced concrete. Many buildings have been designed with the concrete slab extending through the exterior walls to form balconies. Since they are relatively thin and unprotected from the weather, they are vulnerable to corrosion of reinforcing and potential collapse. Many buildings constructed in the 1950s and 1960s are undergoing repair or removal of such balcony structures at considerable cost.

See also 2003 Chicago balcony collapse Berkeley balcony collapse

References

Illustrations

Worked examples

Example 1 — a first encounter with Porch collapse

Start with the simplest possible case. Write down what Porch collapse claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Porch collapse before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Porch collapse ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Porch collapse

In research: Porch collapse appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Porch collapse in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Porch collapse is common in secondary-school and first-year university syllabi. It links to neighbouring topics Building defects, so understanding it makes those chapters shorter.
In everyday life: Look for Porch collapse outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Porch collapse in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Porch collapse means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Porch collapse out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Porch collapse in simple terms?

Why does Porch collapse matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Porch collapse?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Porch collapse.