12120 Anti-earthquake measures

Penny - there are two different camps as regards this the rigid and the flexible.

Italy has plumped for the former and has been doing so for a number of years; rigid is in the sense that the reinforced concrete structure forms a rigid cage that may distort and crack but should not even with the most violent earthquake fall in on itself and kill occupants. I think you'll find it works however it rather depends on building control by local councils.

The new camp is as in Japan the flexible with wooden buildings that flex.

Both work well when built correctly and checked.

Here in Italy there are other political issues the cement, steel and brick industries lobby hard to keep cement and steel content high and still allows an in-fill compromise "brickwork" which kills more people than the concrete cage that encompasses the building. If they allowed more monolith structures things could be better but it will still take decades if not centuries to change the whole stock.:SLEEP:

What about when you have two methods together in one building? We used to have a timber-framed roof, but were given a concrete skim when we decided to insulate it. We still have timber beams, traditional coppi etc, but now a couple inches of concrete. I asked at the time if this would impede the flexibility of the house, but they said it was necessary to get the roof straight enough for the insulation. The rest of the house is beams and stone, with iron tying rods underpinning one floor. The house shuddered through the Monday earthquake and all subsequent aftershocks, and I guess I'm being a bit on the hysterical side, so apologies if I appear paranoid. It's just that I've also heard that the traditional building techniques are good, and wondered if we've compromised this. Many thanks for any enlightenment!

I guess I must be missing something here.

Are the "traditional building methods" being promoted by this architect the ones used to construct the buildings which collapsed catastrophically during the 1915 Avezzano earthquake and killed 32,610 people? Traditional methods were also used to build the structures whose collapse during earthquakes resulted in 60,000 deaths in Sicily in 1693, 50,000 deaths in Calabria in 1783, 11,000 deaths in Naples in 1857 and so on.

I can't comment on whether there is any scientific evidence supporting the modern anti-seismic methods used in Italy (a ring of steel-reinforced concrete on top of all walls integrated with a steel-reinforced concrete roof), but it does seem pretty clear that there's very strong evidence that the traditional building methods create earthquake death-traps.

We, too, live "just" 35 km from the epicentre of the major earthquake on 6 April 2009. The part of our house that was built seven years ago is showing no signs whatsoever of being affected by all the tremors we've felt here. The part of our house which is very old but had anti-seismic work carried out on it a few years ago has developed a few hairline cracks in the interior plaster, but shows no other effects. However, an extension on the house which was built using traditional methods but had a concrete roof slapped on it – which I'm pretty certain was done at a time prior to anti-seismic measures being compulsory – is showing some major cracks in the roof. Make of that what you will, but I draw the conclusion that modern design standards implemented by a competent, conscientious builder work as advertised and will withstand some shaking.

Anecdotally, while driving around in this area, we've noticed no damage to modern buildings, but we have seen a few traditional buildings with piles of rubble outside which have fallen from roof or walls.

It seems to me that, given the distance of the Hotel Sextantio from the epicentre, if other structures nearby are showing major damage while it remains unharmed, that very likely says something negative about the quality of materials and builders employed in those other buildings, rather than proving that the methods used in the Sextantio are the only correct way forward.

Personally (and as someone who grew up in an area subject to earthquakes where wooden buildings predominate), I'd feel happier in a low-mass, flexible structure during an earthquake, but it's difficult to see how one might convert a traditional Italian farmhouse with metre-thick walls composed of rocks into a bendy building.

I know I'm being cynical, but I suppose the only solution to that problem would be to hire a certain architect who specialises in such flexible structures to oversee the demolition and rebuilding of said house.

Al

I I visited Santo Stefano in March and the tower was closed for repairs and was considered unsafe. So it was not a surprise to me that it collapsed during the earthquake.

I think, and I’m no expert, just someone who has experienced the tremors, that an awful lot depends on the direction of the earth movement.

The major earthquake in L’Aquila, shook our house from side to side, we suffered no damage, and very little was disturbed (except us) in the house, whereas the aftershock which was centred further north near the lakes, made our house shake from front to back. Again we were lucky and there was no structural damage but all the glasses on the dresser fell and smashed.

I think if there is a weakness in a building it may survive a shock from one direction but not another.

I’m certainly glad that I have a seismic ring under our roof and the only house really near to us which has sustained really bad damage was an old traditionally built house which was already partly ruined.

This is a subject very dear to my heart and anyone who knows our project will also no we have restored our old pre 1800's house mainly on our own and by hand using lime mortar and no cement.The roof was done using a geometra so we had to have siesmic ring but still reused old materials. All repointing and consolidation work has been in lime and we are putting down a limecrete floor on top of compacted gravel to replace a rather badly 'made ' rubble and earth floor that fig tree roots running thro it!!So far the house is fine after all the shocks.

Many of the old stone houses that collapsed in this quake are constructed from a mortar made almost [I][B]entirely from mud[/B][/I] - as builders would not have been able to afford lime. This is very weak and although it seems to do a job in keeping a house standing it will not work in earthquakes.Thus all these collapsed houses - nothing to do with not using cement.

If we were starting from scrath-something I'd dearly love to do I would chose a single storey straw bale construction or even a rammed earth construction. I'd plaster in lime and used clay paints.

I'm convinced that most Italian buildings built over the last 60 years are more of a hazard in an earthquake than [I][B]properly restored and maintained[/B][/I] tradional stone houses.

Is this because the lime mortar remains flexible and therefore allows the house to move more?

There have been structures built in earth quake prone Japan, that have incorporated in them massive blocks of concrete on equally massive springs that are designed to "absorbs" the energy of a quake, that counter balances the energy tranmitted through the building. Flexible rather than rigid. The trouble with rigid steel re-inforced structures is that the energy is "transmitted" throughout the whole structure. Until sufficient energy is built up and a point of weakness is found. Secondo me....
Sprat

the whole thing about either modern or new building is that whatever is done has to be an integrated approach depending on factors from well below ground level to roof top...

most serious loss of life in aquila was due to under maintained properties or public institution new builds.. this in fact was a quake well below the factor that seismic laws render buildings here safe to be in...

the public building scandal invsetigation in l'aquila in the first preliminary findings have found that sea sand was used in the cement production and under sized steel rods ... they will also most probably find that when they look at the rods anyway they will not have been fit to have passed through a sonic test of their purity... concete and salt are two enemies ... causing cement not to set properly at all

i am not saying there would have been no deaths in l'aquila but there should have been far far less...

many of the problems have also been caused by churches collapsing on neighbouring properties ... because tall towers and steeples have never been maintained according to standard... indeed it might well be that all church properties are exempt from building regs in any case

anyway back to buildings...the Italian system has no real fault to it compared to the flexing system as long as it is actually applied... geologists testing the ground and then drilling holes to infill with re enforced concrete to the required depth.... one house... just a house we worked with had 16 meter columns into the ground... before the house was even started on... but this concrete has to be of a certain strength and should be certified ...the steel is tested for impurities...

older properties if they have not cracked in the past can benefit fro a sort of ring around the base of re enforces concrete... because the effect of a quake is a sort of bowing movement almost as if you are jumping up and down and the middle floor of your house is the knee joint...

if the calculations are wrong... by adding weight to the roof and a seismic ring without integrating it with rod-ding through the floors to the outside walls you are adding a weight the house was never designed to take at stress levels and so it collapses...

older properties that have had water penetration over a long period need both tying and caging unless they are demolished ... the caging is with steel mesh and spayed with concrete.. . the only safe alternative to that is to take down and rebuild...

so it s no use looking at a single item on your house... its a complete system from top to bottom... and in general well maintained properties here with anti seismic additions built on rocky outcrops... its where most old properties were built will survive happily...

the main problems are institutional new builds or refurbs... this is where there is big money to be made amongst criminal elements and local politicians and comune technicians... hence sand used in L'aquila dug up from beaches... most probably not in Abruzzo but transported here... and used by the building companies based in Abruzzo and tests ignored by comune architects and geometras... obviously these lorries would have been taking other stuff out of Abruzzo for other abruzzo companies to dump it somewhere ... usually hazardous waste...

the other point is time taken here... people often complain that building work is so slow here... in all builds either private or public .. once a layer of re enforced concrete has been put in... it should not only be shuttered and supported but no weight should be added for thirty days... and this can even be extended by temperatures... this then needs testing before permission is given for the next layer to be added... .. its another quick way of cutting corners ... and reducing costs...

anyone that doubts the ability of local Italian politicians and their technical people from architects and down wards to the building companies just has to go into detail of the molise quake in 2002 ... from memory ... most of the children that died in the only building to collapse were sons and daughters of the people involved in the design, build and approval of that new school......

what is worse ...far worse is that all these places are built on the major fault lines so its never a question of if just when... but this is the 21st century and the rules and laws have been there a long time and what ever method you choose both systems are designed to protect everyone from a major quake and on the scale of things this was not anywhere near the tolerance the laws are designed to protect our lives with

sorry its something that drives me carzy here... they will blame it on the rules not being good enough... the rules are here...in private work generally followed ...its the people that make the rules that are the ones that break them.. italy does not need any debate on the fact of the type of rules for earth quakes what we need is someone for once to throw the lot of the local politicains in prison... for ever... for not following them and once again letting the young people of Italy die

pilchard we posted at the same time (well this lot took mne a lot longer to write)and i dint see your reply... i dont want any arguements ... its not me disagreeing with you and on talls builds i would entirely agee with what you say... and i am sure there are various ways to beat buildings falling down...

where the funerals were held yesterday in aquila is the school for the guardia finanzia here one of the only public buildings left standing ... who was ever going to get caught cheating on them... soi t most probably got built properly

Smallpox, wife-beating, malnutrition and keeping pigs immediately next to your bread oven (at least at our place) are all very traditional. Something having been done in a particular way for a very long time does not prove that it must be the best possible way of doing things; it doesn't even prove that it's a good way of doing things. Sometimes it indicates nothing more than that our ancestors were not able to come up with a better solution given the resources available to them.

Having said that, anyone who thinks concrete is not "traditional" clearly needs to wander about the Coliseum and take a look at the structure of the building under the brickwork and the remains of stone cladding.

A thought experiment:

Imagine two buildings, one made out of stones piled loosely on top of each other using, as Becky has suggested, nothing more than clay as mortar and another one that looks like one of those enormous concrete coastal artillery emplacements which the Germans built along the Atlantic coast during WWII. Now imagine them being shaken by an earthquake.

The house made of an unconnected pile of stones is very flexible, but it's brittle so it won't cope with an earthquake at all well. The bunker is inflexible, but it's tough so it could laugh at an earthquake of much greater magnitude that the one a few days ago in L'Aquila (which is not to say that the contents – people and objects – would cope well with being rattled about like peas in a biscuit tin).

Flexibility is not always a positive thing when it comes to buildings in an earthquake.

I have difficulty understanding why traditional lime mortar is supposed to be a much better material to use in earthquake zones because it is more flexible than concrete. I mean, it's not like it's as bendy as silicone so rock walls held together with the stuff will wobble about like a jelly for a while before settling down neatly in their previous state. I can see how walls flexing and shifting might be a virtue compared to total collapse, but surely that sort of movement will mean that you have a lot of cosmetic problems with plaster on the inside as well as much more serious structural problems due to walls – or parts of walls – shifting around and no longer being where they used to be?

[quote=pilchard;116062]There have been structures built in earth quake prone Japan, that have incorporated in them massive blocks of concrete on equally massive springs that are designed to "absorbs" the energy of a quake, that counter balances the energy transmitted through the building. Flexible rather than rigid. The trouble with rigid steel re-inforced structures is that the energy is "transmitted" throughout the whole structure. Until sufficient energy is built up and a point of weakness is found. Secondo me....
Sprat[/quote]

I don't think it's really a matter of energy from an earthquake "building up" – as in reverberating and somehow amplifying within the structure – but it is the case that it's impractical to try to construct a building that can cope with any degree of external stress. Deciding how strong a building has to be is always a matter of estimates, projections and probabilities, and those sometimes just don't work out as they're supposed to in the real world. Even the pillbox I mentioned above would shatter under the force of a nuclear blast or the nearby impact of a meteorite. That failure would, as you say, start at the weakest point (and there's always one of those).

I'm happy that I was in our house with its rigid steel-reinforced concrete seismic ring and roof rather than in a completely traditional house during the earthquake last Monday. However, I'm also certain that this place is not indestructible; I think it is entirely possible that a massive quake much closer than the L'Aquila one could result in the roof and seismic ring shaking right off the tops of the walls and pancaking everything under it as it falls.

Contrary to what many people these days want to believe, there's no such thing as "perfectly safe" out here in the real world.

Al

Allan totally agree about no such thing as perfectly safe but will have to question your use of concrete ( or cement) to desribe what the Romans used. Actually mostly they would use a lime mortar but add volcanic ash which today's builders know as 'metastar' ( in the uk at least ) this actually helps to give a quicker set to the mix and makes a 'stronger' but less flexible mortar - not always the most desirable result.

Sometimes brick dust is used for the same reasons.

If you look at the stone in many parts of Abruzzo its mainly Limestone sometimes quite soft.Cement mortars let moisture into the stone weakening it so instead of strong relible stones you get decay.We've had to replace about 10% of our stones as they decayed from cement damage.

And I'm no believer in blindly following tradition. As I said the mud mortar was used out of need rather than the desire to create a strong building.But there may be something said in favour of observing where houses were built - often new houses are put up on soils that carry a high risk of liquidification at times of earthquakes.Totally stupid!

I'll attempt to reassure English Teacher that her mix of traditional and concrete is okay. You have got a fairly thin layer of reinforced concrete on your roof, and that is performing a sort of glueing function, rather than a loadbearing role. In a normal sort of earthquake it will stop the ceiling tiles shuffling off their travetti, and also probably restrain any lateral movement if the principle travi. The steel tie bars in your floors are a very good idea (in my opinion much better than a cordolo of reinforced concrete).

Traditional (Italian) building collapses in earthquakes usually follow the rules that principal rafters, or the ridge, (or ocasionally the major floor beams) lose contact with the wall. The roof beams then knock out the floor beams, and the walls start to break up, first where the beams were seated, and then sometimes more disastrously because they are getting hit by the beams falling from above. (British timber roofs are a much better bet in an earthquake, because almost invariably they are 'tied' at eaves level - which is why you rarely get rooms 'open to the roof'.)

The Japanese 'sprung building' foundations are very clever - if you need to go up to 20 storeys and have to anticipate Richter 9 - but they don't come cheap.

Adriatica tells us a lot about the criminal shortcomings of modern buildings. This is where the dangers of relying on reinforced-concrete (a product easy to take short-cuts with) really become disasters.

One of the best anti earthquake measures was implemented by Norcia, a town in south east Umbria, in 1480. They decreed that nothing would be more than two storeys high. If they had also decreed that all the traditional buildings should be properly maintained at all times, I think I'd consider Norcia a safe place to be!

I don't want this to sound too trivial but, it is something I feel may well be true.

Our villagers, who have experienced minor eatrthquakes, say that their dogs always sense them coming (the vibrations I guess) before we humans do. One local even suggested as much as half an hour before.

So, if your dog kicks off for no apparent reason, maybe you should take it seriously. It may not save your house but it could save you.

[quote=Persephone;116107]I don't want this to sound too trivial but, it is something I feel may well be true.

Our villagers, who have experienced minor eatrthquakes, say that their dogs always sense them coming (the vibrations I guess) before we humans do. One local even suggested as much as half an hour before.

So, if your dog kicks off for no apparent reason, maybe you should take it seriously. It may not save your house but it could save you.[/quote]

So go adopt a stray dog now :yes:

[quote=myabruzzohome;116101]Allan totally agree about no such thing as perfectly safe but will have to question your use of concrete ( or cement) to desribe what the Romans used. Actually mostly they would use a lime mortar...[/quote]
Sorry, Becky, but while the Romans did use the slaked lime mortar you're fond of, they also definitely did use something which would be called concrete today. Although it's not widely known, construction of the Colosseum took only about ten years partly due to large parts of it being constructed from brick- and stone-faced poured concrete. I'm neither a materials scientist or an historian, so in support of my statement I'll just do a couple of cut 'n' pastes from the Wikipedia page on [URL="http://en.wikipedia.org/wiki/Roman_concrete"]Roman Concrete[/URL]:

"Roman concrete was based on a hydraulic-setting cement with many material qualities similar to modern Portland cement. By the middle of the first century AD, the material was used frequently as brick-faced concrete, although variations in aggregate allowed different arrangements of materials. Further developments in the material contributed to structurally complicated forms, such as the dome at the Pantheon."

(The Pantheon is a very interesting structure because the builders used different types of aggregate in different areas of the dome: heavier, solid travertine gravel near the bottom for greater strength, but increasing proportions of volcanic tuffa and pumice in the parts of the dome closer to the centre to decrease it's weight and so reduce the internal stresses on the dome.)

"Concrete, and in particular, the hydraulic mortar responsible for its cohesion, was a type of structural ceramic whose utility derived largely from its rheological plasticity in the paste state. The setting and hardening of hydraulic cements derived from hydration of materials and the subsequent chemical and physical interaction of these hydration products. This differed from the setting of slaked lime mortars, the most common cements of the pre-Roman world. Once set, Roman concrete exhibited little plasticity, although it retained some resistance to tensile stresses."

If you're [I]really[/I] interested in this topic, "[URL="http://books.google.co.uk/books?id=qGb4pyoseH4C&pg=PT204&lpg=PT204&dq=Colosseum+concrete&source=bl&ots=Uc9sbPnV-U&sig=_3MQlUBTgoTOwedgkTC3arINx0g&hl=en&ei=4e3gSaW0CdiNsAaw1OneCA&sa=X&oi=book_result&ct=result&resnum=4#PPT204,M1"]A World History of Art[/URL]" discusses at some tedious length the effect of the development of concrete on Roman architecture.

The much more superficial Wikipedia article briefly discusses why Roman structures in concrete have managed to survive earthquakes over the centuries. It also states that:

"Rebuilding Rome after the fire in 64 AD, which destroyed large portions of the city, the new building code by Nero consisted of largely brick-faced concrete. This appears to have encouraged the development of the brick and concrete industries."

So it seems that the brick and concrete lobbies mentioned earlier by lotan are fairly well-established. :winki:

Al

BBC World Service – One Planet, covered the L’Aquila earthquake and discussed the building techniques.
If you want you can listen here.

[url=http://www.bbc.co.uk/programmes/p002mrwk]BBC - BBC World Service Programmes - One Planet, 09/04/2009[/url]

Many thanks to everyone for their thoughtful and reasoned replies.

[quote=Persephone;116107].....So, if your dog kicks off for no apparent reason, maybe you should take it seriously. It may not save your house but it could save you.[/quote]

My dog slept through all the tremors and quakes so he wouldn't be much use!

[quote=Penny;116167]My dog slept through all the tremors and quakes so he wouldn't be much use![/quote]

My dogs also slept through it all but the cats made themselves scarce. A friend told me “If a cat leaves a room quickly, follow it!” Good advice I think.

Many apologies to most of you who rightly are not so interested as I am in Lime and building with lime! But Allan does the article on the building of the Collusseum not mention a mortar made of lime and volcanic 'sand' - I though Pozzolano was ash but it seems to say here its sand ? This is lime mortar surely? Do you mean as it sets harder than lime mortar without pozzolano or brick dust it's described as concrete?

A hydraulic mix is mentioned and the Romans did seem to make use of hydraulic lime ( with a proportion of clay ) that could set under water or in damp conditions.Castorama still sell this brown coloured lime and its very useful for making a lime mortar for damp areas.

As far as I'm aware concrete [I]as we know it[/I] was invented around 1820 and the big difference was its ability to set very soon after water was added whereas lime mortar sets by a different process taking some time to reach full strength ? A bit of a disadvantage in earthquake situations but possibly there could be an advantage in its plasticity?

One of my football team colleagues has just got a post researching Roman mortars, although from the point of view of restoration and integrating new mortars with old. Having a chat after training last week she agreed that there was still a lot they didn't know about the exact composition of the old mortars.