longest. >> the major issues that follow include plumbing, fire sprinklers. >> mechanical. >> what is mechanical? >> heating and air-conditioning. >> these are residential units? >> correct. >> there are more services that may be an empty commercial office? >> this is true. >> let's work our way out. we have drilled, poured the first floor slab. >> you get the first floor slab port, then we start on the vertical columns and walls. then we start the decking. we are always chasing the cycle. >> how thick is the ground floor slab. >> 10 inches. the other floors are about 7.5. >> you are a structural engineer. you are one of the engineering firms that the city hired after the 1989 earthquake to evaluate

the damage residents. we have a long and good working relationship. they are building this and they are doing post-tension slabs. what is that? >> it is a construction method that uses high strength tendons to work with concrete and make the concrete sections a better section for bending. it has a lot of benefits. the reduces the thickness of the slab, it reduces the number of cracks. the result is a nice, flat slab with very little cracks. >> we now have a piece of this post-tension material. tell us what this is and why this is so wonderful, which is. >> this is called unbonded, because of this plastic sheeting.

it is not bond to the concrete. >> why do you want to do that? >> because there are two methods of decreasing stress. one is posttensioning. the other is pretensioning. this method that we are using is a very conventional for on-site stressing of the slab. what it does is it does not bond to the concrete. you put the form up, he placed the attendance. >> this will be or is not all. inside the floor. -- this will be horizontal, inside the floor. >> this is the anchored and of it. there is a parable -- parabolic profile tendons. their lowest in the mid span and they are the highest above.

what happens is once that you place these inside of the form work and you have the other reinforcements, you pour the concrete. at a certain point where you have adequate curing of the concrete, which is usually about two-thirds of the strength of the concrete, then you jack these and pull them. >> you pull them with hydraulics. you attention it. >> it does two things. it puts large. compression into the concrete slab. because of the profile, it also lifts the slab. that is how you counteract some of the debt load -- dead load. >> how long is this intended to last? >> the life of the structure, basically 50 years. but it could go on.

>> let's talk about that. the anticipated life of the building is? >> usually 50 years. >> this is a big issue in san francisco. i say that because we're now seeing buildings considered historic resources, if they are over 50 years old, they may have historic value of any sort. seems once a building has reached a certain age, 50 years or more, it could be here a long time. we do not really go through buildings every 20 years. we see some assemblies put into buildings, especially high-rise buildings, window wall assemblies, which have a reasonable life span, maybe 30 years. what that means is after 30 years, you have to expect to go in and replace the window wall assembly and all of its pieces. in some cases, the financing and

the owners, wherever it is, are not really aware of all of these different life expectancies with the building. it is an issue that we're trying to sort out. we say this is what we anticipate a reasonable life span of the building to be. the components need to be suitable for that anticipated life span. this is something that has to be because a guy easily take them out and replace them. >> that is right. >> this is one of the determining factors of the life expectancy. does that make sense? >> that is right. usually, there are no problems with post pension slabs. corrosion could be an issue if anchors are not put incorrectly. >> you see these anchors? >> if you look at the edge of the slab, you will cd circular holes that are filled with

grout, and the cable is cut. >> as you look at the crane, you see on the edge of the slab holes, and there are typically three together. >> it depends. >> it depends on where they are. there will put a hydraulic jack on that, tension in it, and philip. we need to make sure that water is not get in there or you may have corrosion. i think we need to back up a little bit. this building is essentially a concrete building. it has steel reinforcing in it because concrete is very strong with compression, when it is pushing down, but it is not very strong in other dimensions. you could imagine taking a long concrete bar and bending it, it will break easily. not much capacity with attention. -- not much capacity with

tension. used to steal for the tension forces. this building is sort of a traditional, prescriptive we designed concrete building. that means they are building to building strictly in accordance with the cookbook requirements of the san francisco or california building codes. it this is a building we are very confident will perform the way we expect it to perform because we have built tens of thousands of buildings just like these, the structural systems. >> that is correct, it is fairly conventional in terms of residential construction. >> will we have our concrete walls, reinforced with steel. i have a couple of pieces of steel. >> this is called mild steel. this is not high strength steel, which is used for the attendance.

-- better used for the tendons. these are used for columns and foundation. these are 60 psi. >> this is available in all different sizes, eighths of an inch? >> number 3 is 3/8. >> number 4, number five, maybe 5/8. let's pass this around. it is heavy. it is deformed. tell us what that means. >> in the surface of the rebar, that is what engages the reader are with the concrete and creates the section that works with the compression. >> it is rough, and roughness of it connects or secures to the concrete. when i was in kobe, japan, right

after the 1995 earthquake, looking at some of the damage, i saw some failure of concrete structures where they had non- deformed read bar -- rebar, smooth steel, and concrete just pulled right off. this has been deformed, which has been used 50, 100 years? >> i believe after the 1930's, he formed rebar is what is used. >> this is standard. that is used in the vertical wall, almost any place except for the special slabs. >> the slab also has reinforcement, but it has much less than a conventional slab. >> they poured the slab one grade, sitting right on the ground? >> it is one great, but it is designed as a structural slab. we are counting on the bearing of the slab on grade because of

the poor soil underneath. we used a structural slab. is interconnected, going back to what john mentioned with the pilings and the caps. >> even if the ground underneath the building settles, which it could do it in an earthquake, the slab will retain its application and integrity and strength. >> that is why it is 10 inches, thicker than your normal 5 inch slab. >> why should it be thicker than the floor above? >> because the slabs on grade is a conventional slap, it is not post tension. >> one of the things the building designers do is to make the floor as thin as they reasonably can. >> there are several benefits to that. first of all, it reduces the

mass of the building. we have 7.5 inch slab. conventional slab would probably be 10.5 inches, which is about 25% more concrete mass. it also reduces the overall floor to floor height, which helps with the architectural facade and the square footage. >> one of the things people are always looking at is decreasing the floor to floor height, especially in san francisco where we have clearly defined height limits, and maybe could squeeze another story and there if you are good at it. we see a lot of people struggling with the thickness of all these assemblies, both the structural assembly and non structural which might be above the ceiling, where we have the heating, ventilation, plumbing, fire sprinklers. you say that the finish of the concrete slab can be exposed?

>> in our building that is the case. >> that would mean you have exposed footings? >> the utilities, they are stealing the utilities, is that right? -- they are ceiling utilities, is that right? >> i am with the associated architects. within the dwelling units, which are not air-conditioned, the concrete ceiling is typically exposed. in most public areas, which may be heated and cooled with forced air, that is where you get the dropped ceiling. also, corridors and public areas. >> the dwelling units do not have air-conditioning? >> they do not. they have heating but not air conditioning. >> do they have outside air? >> absolutely, they have windows and they also have a system called z-duct, which provides

for a share even when the windows are closed. >> one of the reasons they have the systems, ever since 1974, chapter 12-day of the building code requires that you have sound transmission isolation between dwelling units so they cannot hear their neighbors, and between the residential units and the cars at outside. that specifically says that if you are in one of these noise areas, which are on the transit corridor, that you must design the building such that you can ventilate the resident units with the windows closed, meeting all the noise control requirements. you close the windows and you still have enough ventilation, which is why people use z-ducts. >> that is correct. the bathroom and kitchen exhaust fans are on at a low-level all

the time. even when the windows are closed they are always pulling in adequate amounts of ventilation from the exterior. >> are there any other special noise control features? >> the code required what is called sound transmission walls between the units. between units above and below also. the concrete floors are very good at deadening air-form sounds, but impact sounds are harder to control. you could imagine a shoe reverberating through there, so we have to provide padding through hard finish material such as title or sheet vinyl to death in the sound. -- to daeden that sound. >> that means there is a specific floor assembly that goes down. maybe a carpet with pad.

people 5, 10 years from now say i will replace the carpet or the linoleum, they do not fully understand that as part of the sound transmission assembly, required by the code, and to protect them. in many cases we see lawsuits from the generation of sound transmission. also, the walls between dwelling units, they are making the walls out of light gauge metal studs. in order to make the sound transmission work, you have to do these exactly right. you have to have the sound isolation between the sheet rock and the stud, and stud and the sheet rock on the other side. how are you doing that? >> we have a couple different wall assemblies. there is one that goes between units, st. ford assembly with two layers of dry wall -- straight forward assembly with two layers of dry wall. then we have a sound wall

assembly for the shaft. that is a special stub that allows you to insert the dry wall panels from the side that you are standing on. >> we are looking up and i see this crane. we have been reading about crane issues and safety. come over here and tell us a little bit about safety on this structure, the safety program, and about how the crane fits in. >> it is probably one of the most dangerous pieces of equipment and it is the most rigorously protected. we had cal osha out here doing test weeks. >> cal-osha comes out because the state of california, unlike the city of new york or other places, in the state of california, cranes are inspected by the state, not the local jurisdiction. in the wake of the crane collapse in california in 1990, the board of supervisors passed legislation which is now still in it regulations in the

building code that requires crane safety programs to make sure that the building department is collecting all the information, but we reply. we rely on kali should do the actual infection. what did they do for an inspection? >> they bring about 20,000 pounds of test weights and check all the weight limits and wells and electronics and connections and the limits. they do everything. >> is there somebody up there right now? >> there is thomas in the cab. >> can you get him on the radio and have him we've to us. -- and have him wave to us. there is a job. >> there is no bathroom. we will not discuss that. >> the safety rules say there have to be some provision. >> there is a provision. >> don't stand under.

>> we have a couple of different kinds of cranes around the city. we have a fixed height crane, like this, and then we have some that are climbing cranes. >> this is a free standing crane, not bolted down. about all of these big concrete waits? >> 160 pounds of concrete is the ballast week. >> did you have to pour a big foundation under that? >> this is a construction method that we get to, we work with the contractor. we get a load from the crane manufacturer, figure out the downward load and the overturn load. we then make sure that the foundation can take that load. also, all the anchors on the floor are adequate. >> why would you do this instead of fastening it to a fixed base? >> this crane is not part of the

foundation system, so it is out board of the structure. basically, it is something that worked well with the courtyard and a landscaping and the irrigation outside. in one month, the crane that is going up will be part of the foundation. >> bolted to it? >> exactly. >> the other kind of crane, which worked their way up as the building that's taller and lift themselves up and slide and. >> those are climbers. >> the climbing crane. it was a climbing crane that collapsed in 1990. >> we do not like climbing cranes. >> they are safe if they are done correctly. no margin. not much margin. >> how you get one of those set up if it is not a climbing grain and there is a fixed piece underneath? how does that it set up? >> the crane is brought in it in

sections. as the foundation is poured in, the, up with a mobile crane unit, put out the section, then they build the jib on the ground. >> what list it up? >> 225-ton portable crane. >> they bring out another crane to set up the cream? >> exactly. >> this particular crane is brand new and it automatically shuts down at 35 mob. hour wind. -- at 35 miles per hour wind. >> i got a call a while back from some neighbors who said the crane was spinning around, free- spending, and i am worried. when they shot down, they're not fixed into position. they are allowed to rotate freely with the wind. weathervaning. when their shutdown, they'd still move because it reduces

the load on the crane. >> i am wondering to what degree the guy at the top is typical there? and the weight will have a strain the further out. the u carry weight that you would not be able to take to the end of the boom? how you keep from it malfunctioning and going to the end of the boom? >> basically it has a 145-foot jib on it. as you go out, the capacity goes down. this crane is good for about 17,005 propounds at 50 feet. there are warning systems on the crane. if he actually tries to override the system it will shut down. the only thing he will be allowed to do is drop a load. >> as the ground moves, if you exceed the 3 inches that you have designed for the building

to settle down, what would happen? how would that movement transmit through the floor? >> most of the settlement takes place right after construction. the settlement that there were mentioning his total sediment, due to the mass of the building itself. once we get an earthquake, the foundation is designed such that all of the friction forces against the piles resist any further displacement. there will be some displacement, but it is all calculated into the computer model that we have generated. >> how much settlement would you expect from the initial baseline? >> typically, with piling foundations, 1 inch or less. three-quarters of an inch is what is expected. >> does that impact any of the systems in the building or

anything? >> most of the settlement occurs during construction. as you lower the material a continues. what she did most of the building structure up, then you put the finishing on it and you cannot see the cracks because most of the settlement will be gone. >> let's talk about greene design. a big thing and san francisco, before the board of supervisors, is legislation, if this building were built next year, would require that this have eight lead certified building, silver building if it were built next year. what kind of green provisions are built into the building? >> we have done as much as we can with the checklist with the limitations and budgetary constraints that we have. we're hoping to be certified to achieve just under the lead

silver level, although we're not going for the certification because of the process on this particular building. >> can you mention specific green building construction strategies? >> we have worked with our structural engineer using flash in the concrete. >> what is that and why is a green? >> it is a byproduct of industrial waste, basically, the smoke from the smokestack, ash that is collected. it provides a great material, a great part of the concrete mix. it is recycled and is relatively inexpensive, although it is getting more expensive because there is a lot of demand for it. >> any other green -- >> it affects the curing of the concrete, prolongs it.

>> does it affect the ultimate strength? >> it actually improves it. >> as far as the budget, with our contractors, because of the curing time, it is expensive. we could have put more cash in the concrete, but the more they put in, the longer the curing time and the longer the schedule and the higher the cost. >> any other green features of note in this high-rise? >> there are a number of features, such as using recycled products such as carpet, cabinetry, things like that. we are using what they call no added formaldehyde wood in the cabinets. the building is largely not air- conditioned, which in our climate, it is benign, so it

allows that. that is a green point. >> what about water strategies? >> when you talk about lead certification, a lot of the factors taken into account are things we are able to achieve just by virtue of the outstanding location, walking distance to the best transit hub in the city. we have walking services for just about anything anybody could want. >> we have high efficiency boilers to heat the water. it is a water source domestic heating system. >> what is next to the tower crane? we have a big blue piece. what is that? >> that is a concrete placing boom. that is how i put the concrete up onto the deck. the concrete truck will back into here, go to the hopper.

then i have a slight line that runs up the center of the boom. that completes all the dax, walls, and columns with that. >> it must take a lot of power to push that. how much concrete do you typically place? >> on an average day, the walls, 147 yards. the deck is about 210. >> how much is in a truck delivery? >> 10 yards. >> so you have a bunch of trucks backed up, all day long. where is the concrete coming from? >> we have bodie concrete off of third street. >> there are not that many concrete suppliers left in san fences. they used to be a bunch. is there anybody else beside bodie? >> we like bodie. >> they are bringing concrete in from a distance because there are not many yards anymore. in general, san francisco, part

of the planning issues and san francisco are the loss of p.e.r. production and construction related services. we still have some, but now we're seeing more and more of these services outside of the city and the cost goes up because you have to import goods and workers. when you get your bricks fixed in your car, pretty soon you'll have to go outside of san francisco because it is becoming not a friendly place. i know the planning department is working hard to keep it in its working condition, and i wish them luck. the way that these concrete walls are don is typically there is a prefabricated panel that is set in place. these prefabricated panels? >> plywood and to and studs. at the top, those were poured yesterday. we will take them apart.

>> it has formed release material so the concrete is not stick to it. >> correct, it is a special plywood with a finnish sauna that lets it strip easier and then we also spree with oil. >> than a pop these apart and reuse the panel's. >> we will change the plan would usually one time through the 12 story building is because the plywood starts to get worn. >> howdy keep everything perfectly lined up? -- how do you keep everything perfectly lined up? >> we have control lines and we have crude lines -- and a grid lines with the surveyors. we plumb everything up. >> about how close, what is the tolerance? >> before it is tension, within a 16th of an inch. as the building gets