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tv   [untitled]    August 17, 2010 5:00am-5:30am PST

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car, these hills became accessible. he watched horses be dragged to death. cable cars were invent in san francisco to solve the problem with it's unique, vertically challenged terrain. we are still using cars a century old >> the old cable car is the most unique thing, it's still going. it was a good design by then and is still now. if we don't do something now. it's going to be worse later. >> the cable cars are built the same as they were in the late 1800's. we use a modern machinery. we haven't changed a thing. it's just how we get there.
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>> it's a time consuming job. we go for the quality rather than the production. we take pride in our work and it shows in the end product. >> the california line is mostly locals. the commuters in the morning, i see a lot of the same people. we don't have as tourists. we are coming up to street to chinatown. since 1957, we are
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the only city in the world that runs cable cars. these cars right here are part of national parks system. in the early 1960's, they became the first roles monument. the way city spread changed with the invention of the cable car. >> people know in san francisco, first thing they think about is, let's go
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the hayward fault and continues >> welcome to the building department brown bag lunch series. today the topic is earthquake safety. as we do every month on the third thursday, we invite you t come sit with us. i have invited today an outstanding expert in earthquak
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safety mr. pat buskovitch to join us. there he is, thank you. he's our answer man today. our focus today is on home earthquake safety. we're going to start by looking at some slides and using the slides as a -- as a sort of spring board for us to discuss issues. then we're going to go through some stuff that is recommended you have in your homes, and you can see what i have in my home over here. this big box of emergency supplies, right out of the garage still covered with cob webs. let me just start by saying -- showing you a little map over here. and this map shows san francisco. i don't know why san francisco is white, actually. but here's san francisco on our little map right here. it shows san francisco being -- here, pat, you can help me with this. you can see san francisco is between two major faults.
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the san andraaes fault, which ruptured during the earthquake our centennial next year, and you'll know that san francisco is between the two faults. there's no escaping the nerks earthquake. the usgs just revised their probability. it's this. it's a virtual certainty we'll have an significant earthquake in next few years. it's going to happen and it's like to happen in the next 20 years. >> you should count on it. >> you should count on it. we're not talking about a possibility. we're talking likelihood or ineffability. as we move on -- >> can i point out one thing, one of the reasons they believe this is a certainty, not a probability, is there is a
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theory that the 1906 earthquake released so much energy, we had a period of quiet. that's over. before 1906, we had big earth quaiks on a regular cycle here. we had big earth quaiks over here. '06 released the earthquake energy. if you start traifg the fault, every 150 years there's a big earthquake on the hayward fault the last big earthquake was in the 1850s, so we're on that 150 year return cycle. on the san an drees, we had an earthquake down here. there's a belief what is happening is the earth quaiks are moving.
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two earth quaiks from now we'll have an ep center up here. it's pretty much our time in th next 20 years. if you actually talk to geologists, they're front loading it. they may say it's a virtual certainty in 20 years, but they're saying it's not five percent a year, 20 years into a hundred percent. it's 10 percent a year for the first ten years. it's so front loaded. we're overdue. >> let's stipulate to the fact. an earthquake is going to happe in the relative near future, ou lifetime near future. although maybe i'll be retired by then. >> we'll drag you out of retirement. >> okay. let's look at strans itself. we have a seismic matter map an
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it's -- it has been formally adopted by the state and the city uses this map. it shows us certain areas of th city as having high probability of liqii faction or soil stability. typically, you have the various kind of soil failures you might have, buildings can settle, spreading where the soil spread out into the bay, say, for example. you have amplified ground motion when the soil is wet or when they're unusual soil conditions, a little bit of shaking gets amplified through the ground and you have substantially greater forces. >> who is exactly what happened in '89. in '89 there was a big earthquake down here. there was not a big earthquake
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in '89 here. the motion continued out so the waves got stronger an stroker and when it hit these areas it amplified that motion three times. most of san francisco in '89 shook around nine percent of gravity. i'm explain what that means. but nine. this area and this area shook a 25 percent. keep that in mind. it shook three times harder on this poor soivment when we star thinking about this fault or this fault slipping, the lowest level shaking anywhere in san francisco is going to be 25 percent. the lowest. so your best case scenario of what's going to happen to your house is look at what happened to the marina. over here if the san andreas
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goes off, it will shake twice a po what the marina shook and twice as long. think of the the marina and that's the best case for your neighborhood. >> okay. come on over and have a seat an we'll talk about buildings, you house and what kind of problems you might have and what you can do to help solve your problems at home. i have on our screen some typical san francisco buildings most of the buildings in san francisco are wood frame, over 90 percent. typically they're light weight and relatively strong, generall strong. in most cases, wood buildings are strong because they have lo of interior partitions as well. >> there's a lot of flexibility when i'm pushing you, the building the flexible, he's moving around. >> right. >> so this type of building is great as long as there isn't
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critical flaws. >> which is the good thing to see what is a g. >> gravity. you weigh 100 percent of gravity. >> that's me. >> if lawrence weighs 100 pounds, one gravity down means he weighs 100 down. an earthquake is creating horizonal acceleration this way at the ep pi center, the ground was shaking the buildings at roughly 50 percent. so that would be pushing lawrence with a 50-pound force. that's what going to happen in big earthquake. in '89, the ground shook at nin percent. and i'm not even overcoming the friction of the wheels. so when you think that your building survived -- let me rol you over here.
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at a 25 percent earthquake, if you think it survived a good earthquake at nine percent, that's like someone bunching into you. that was only nine percent of gravity. >> thank you. getting pushed around. so we have wooden buildings and a couple conditions i want to mention here. first, we see buildings up against each other. so buildings up against each other, the likely heed is they'll help support each other >> except the guy at the end of the block. >> he has a real serious problem. also if there's a walkway between buildings, these people have a problem. even if we have these soft stor buildings in the middle of the block with open garages or door ways and so on -- >> or windows. >> at their lowest floor, even those might be soft stories, th building will probably hold up.
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here's a giant corner building. i have a few more pictures. corner buildings are important in san francisco, because they have a lot of character definin features that we love of san francisco. they're billing -- bigers have lots of wonderful trim. >> usually four story where the rest of the block is three, the define the intersections. >> and because of the larger three or four story buildings, usually two or three over a retail on the ground floor, wha we have i recall force equal mass times acceleration. >> or mass types acceleration equals force. >> was that sir isaac. >> i believe so. >> sir isaac newton. this is the building. the more stories you put on the building, greaterer the mass of the buildings. that's one of the reasons they pose a greater hazard.
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here's a soft story building we don't know -- >> it could be steel frames in it but we can't see it. that's what you look for where they have glass on two sides. >> a typical problem hopefully retrofitted. i want to point out, ñithis bui rtion not vul national but they have commercial uses on the ground floor. if these are destroyed, these buildings might collapse a floor, not a huge pile of rubal the likelihood, like in the marina, they come down on the soft story. >> no. what happened in the marina, most buildings got rolled over and crushed the cart. okay. the rest of it stood up. i walked into a bunch of them, you could -- the floors were doing this, but you could walk through the floors but the ground floors didn't exist. >> so we don't want to lose or neighborhood serving businesses as well that's another reason
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those are important. >> another thing. on a four story building, i can tell you how much that building is going to sway in an earthquake. i don't need to know much about the building, i ask tell you that exactly. if the 2, 3rd and 4th floor are stiff,. >> because they have all the exterior walls. >> the deflexion of the entire building has to occur at the lowest level. so instead of having your whole building leaning over nicely, i this -- upper portion the stiff my knees have to bend over. if they bend over so far, the building doesn't come back. that's the double wame of a sof story. >> here's a soft story occupied attic with the ground floor wit a big hole in it. i want to point out these front
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stairways are often made with different material than the building, so they move at a different period of frequency than the building. almost always you'll see separation but not a critical hazard. >> they'll get damaged just pla on fixing them after the earthquake it's cheaper than now. >> now in this slide you see a more modern building. in the earl '70s, '73, '74 is when the modern seismic safety codes went in effect. buildings built after that have a reasonable chance of survivin without major collapse, but buildings built before '74 or thereabouts are the ones we're mostly concerned about. >> the percentage of building i san francisco fre '74 is huge. >> most of them here's another corner building to give you an, we once again don't know, it ma be upgraded but we don't know.
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and there's lots of other types of buildings. there are brick buildings, concrete buildings where people have residential are particular hazard because they're nonductile and not designed to sway back and forth and stop an they're designed to sway, sway and these are the ones we often see pictures of in a pile of rubal. they don't go down one story they end up in a pile of floor slab. we have many in san francisco and we're going to try -- the building department is trying t figure out how to deal with them. they're difficult to retrofit. wood frame, light wait building are easy. >> you can retrofit a wood fram building for maybe -- very reasonable. add a zero to that number and g from there.
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it's a much harder challenge. >> now there are also nonstructural hazards in buildings. we have one at the corner of page and lyon street. look at the chimney other sheet metal. this is getting ready to fall off. it won't take much to have that fall down which most of the people killed in earthquakes ar those outside the building. >> on the sidewalk. >> stuff is falling off the building on to the sidewalk. when someone said what do we do in an earthquake, run outside, that is not a good idea. here's a brick chimney. we have few brick chimneys in san francisco. this is a major hazard. there's little reenforcement an they're incrediblely heavy. >> here's one that's been braif a little bit. that's an original brace that
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will buckle . >> yes, sir. i was curious if you have -- sort of developed deck nothings to retrofit structure reenforcement of these exterior brick chimneys. >> absolutely. some cities have passouts. when i do home remodels, it involves putting a collar aroun the chimney and running some diagonals down. you might have to put two or three collars, but the biggest i issue is to keep the his oric character. it's doable. you just need to know about it. you may be living next to one o these and knock on the neighbor's door and say i reall don't want to have your chimney in my bedroom after an aert quaik. >> yeah. let me mention we're looking at that chick any that has a singl brace. pat says it might take two or three. contractors often say i ool tak care of that problem for you. i say you shouldn't be asking your contractor to design the solution. you should be asking a licensed
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engineer or architect to design the solution and your contracto can bid on the design the architect has given you. contractors are not designers. their job is to read a set of plans and build it exactly that way. if a contractor says let me brace your chimney, you would say let me check with my engineer to see what kind of basis are necessary and you can do the work. okay. contractors do not do seismic design work for the most part. there's minimal things they can do and we'll see that in a minute. here's some kids standing outside of one of his builds where we have a pair pet up there. people hang outside on the sidewalk. it's important to protect the public. >> after the event if you're going to go somewhere, do not g right in front of the building. maybe go to the center of the street although you're going to have to watch for cars, but it'
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not necessarily the safest plac to be to run out after an earthquake and hang out underth earthquake. we also have something called after shocks, so you want to be careful about where you go. >> so i picked a house in my neighborhood to look at in a little more detail. i think this suz built right after ñithe 1906 san francisco earthquake. this is a wood frame building, it's basically a soft story building because it has a big garage door and next to it is a hole where the sair way is, but it's supported by the houses on either side to some extent. so let's take a look at the house. i don't see a whole lot of nonstructural hazards that's going to fall off. inside the garage the lady who owns this had someone put anchorables.
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you see some new wood which covers up where they opened the inside of the garage and put anchor bolts that the contractor came and put in. you say, gee, they put in ancho bolts. >> this is just a basic review. you put some glue in put a piec of steel in, let it set and screw it down. and you've anchored your house to the ground. your foundation isn't going to move because it's integrated into the soil. you don't want your house to slide off the foundation. they do. in the marina there was a house where the ground dropped out an the house moved forward. and that's not a good place to be. you want to bolt your building down. it's the most cost effective, easiest thing automatic you do. it's not discussible. you don't drive a car without brakes, you don't live in a
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house without anchor bolts. >> you put this square washer and tighten up and you're done. it's easy and cheep. most contractors can do that without detail. >> the process to do this is as sirch as you can get. you walk in fill out an application and say install anchor bolt, they'll give it to you. it's not approximately indicate to get a permit to do. it's not complicated for a contractor to do. it's -- it's only reasonable like having brakes on a car. >> a lot of houses -- my house the pre1906 brick foundation in the late 1800s, so drilling in and epositionying people claim is almost more damaging than not. >> you didn't hear it from me because i retrofit four story tall buildings all the time. properly done you can anchor bolt to maybe 90 percent of the brick foundations in san
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francisco. 10 percent the mortar which is generally a lime -sand mortar i so degraded you can't anchor into it. if you want to take out your brick, it's obviously better. are you going to get improvement, a couple percent. >> so people say i have a brick foundation, i really need to replace my brick foundation to improve the seismic performance of my building. that is not where to put your money. we have -- i have rarely seen build where is the foundation, the brick foundation has filed. we see lots of other kinds of failure but not typically brick buildings. >> this is what happens. you've got to put your bolt in first. you have x amount of dollars to spend. they tell you you've got to replace your foundation. that's $100,000. you're not going to get $100,00 of earthquake preparedness or proof with a new foundation. you can put your bolts in for or $4,000 you spent $97,000 getting two percent improvement
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of performance of the building and haven't gotten off of the seal plate. you have a lot of other places to put your money before you ever think of your foundation. >> we had a question about what size anchor bolts , so if you'r doing the job, you should be using 5/8 anchor bolts imbeted 7 inches typically minimal embedment. most contractors are aware of that. talk to an architect, give the contractor specificationings. we want anchor boltings no more than every four or three feet, whatever. tell the contractor what you want. don't let the contractor decide how to put in anchor bolts. i eaten not intending to den great contractors but it is critical. there are two types of bolts , one to prevent the building fro sliding. sometimes you'll see these gigantic things that are hold downs and these prevent the building from overturning or
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coming up off the foundation. >> rocking. >> from rocking, basically. you see these in all new buildings in almost every case. we can apply these as you'll se in a second to some specific application within existing building. so we'll move along here and what marge did after she had he bolts put in, she had some areas of the garage that were open put plywood up. here we have plywood that the contractor installed using little tiny nails too close to the edge, you know, whatever, but not following standard specifics. once again here's why you need to hire someone who says this i what it should be. >> not enough nails here and they don't need these nails there. >> there's no nailing along the top edge. the boundaries of the plywood are the important areas to be properly nailed of all things. okay. here's another area, this is better. i think this is somebody else's
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house, actually. now, along the side of her garage you can see where the wood is and they put the anchor bolts in and the back wall of the house with the kitty litter sitting there. there's no plywood there. that's the wall that really needs to be stiffnd up because that's the short dimension of the house. >> in '89 and most earthquakes in san francisco, buildings don't fall forward. they don't go towards the street. they lien over or rack , so wha you really want to do is anchor bolt all the way around the perimeter of the building, you may put plywood in the side walls but it's the front and back that is critical. because the building wants to, it's usually narrow or tall and it wants to rollover. you want to plywood the front and back if you can and maybe add a footing in the middle.
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it's amazing the minimal amount of strengthing you can do is enough to give a building an excuse to stand up. >> we've looked -- i have and i know pat has looked at hundreds maybe thousands of earthquake damaged buildings. the smallest investment in structural improvement will prevent buildings from collapse >> it's not just the damage. you have to live somewhere else while in is going on. all the things you need to thin about, if your building is damaged you have to find anothe place to live and your life change fs you can't come home and have to live in a shelter. the earthquake that we expect, you really don't want to be living in those shelters. you want to be at home. sfwl let's move along. so in the middle of her house i the garage she has typical tension post that is go through the middle of the building they're posts and the cars run
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into them and they break. typical problem. in an earthquake things are going side to side but bouncing up and down. a serious likelihood is a post will come off the post base, po off and flip around. when that happens that's a serious problem because nothing is supporting the floor above and it settings so it's not going to collapse the building but it could provide tremendous damage to the build. >> you don't won't to have a floor where you walk down the floor and walk downhill. not good. >> the top of the post is once again not connected. here's a t strap five bucks. you put this at the top, drill hole and nail it on. for $40 your house won't have $10,000 worth of damage. >> the thing to remember in an earthquake is ground is shaking

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