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Post by darrell on Mar 22, 2013 12:16:22 GMT -8
On the subject of tensioning cables, here are some details of their use in the pre-cast concrete girders of the new National Blvd. bridge over Ballona Creek: Open conduit ends at right (11/1/08) Conduit passing between girders (right), encased in concrete (left) (11/18/08) Cables sticking out the end on right (2/13/09)
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Post by Gokhan on Mar 22, 2013 12:34:07 GMT -8
Note that there are four vertically stacked tensioning cables in Darrell's pictures of the Ballona Creek precast beams, and the tension must increase gradually from the upper to lower cables to give the beam the following shape in Picture 4 below. Then, when there is a load on the beam, both the upper and lower sides of the beam still stay under compression, allowing the concrete to maintain its maximum strength, which happens under compression. Tension on the concrete breaks it as shown in Picture 1. From here.
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Post by roadtrainer on Mar 23, 2013 14:46:19 GMT -8
Dwight reports that the big concrete Note that the superstructure is sitting a few feet higher than the abutments. Once they build it, they will lower it onto the abutments. I wonder if they will use a large crane (like they did at Motor Avenue when they lifted up the old steel superstructure there) or they have another technique to lower this massive superstructure. Gokham: I dont think they lower the bridge at all If it's higher then it will be higher, but it might be an illusion and once ithe false work is removed it will be the same as the existing P.E. bridge. and here is a question for you -Is the stationat a level or is it sitting at a small downward grade or a steep grade like the USC station?. Well, i was driving a route in santa Monica, and i got on the freeway at (Al) Bundy drive and drove eastbound on the 10. as i drove by the National/Palms station i took a quick look at the bridge and it does apear to be taller than the old P.E. bridge. So manybe my thinking is right, the new bridge is higher and that the station is on a downward grade heading westbound.
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Post by Gokhan on Mar 23, 2013 16:30:34 GMT -8
Gokham: I dont think they lower the bridge at all If it's higher then it will be higher, but it might be an illusion and once ithe false work is removed it will be the same as the existing P.E. bridge. and here is a question for you -Is the stationat a level or is it sitting at a small downward grade or a steep grade like the USC station?. Well, i was driving a route in santa Monica, and i got on the freeway at (Al) Bundy drive and drove eastbound on the 10. as i drove by the National/Palms station i took a quick look at the bridge and it does apear to be taller than the old P.E. bridge. So manybe my thinking is right, the new bridge is higher and that the station is on a downward grade heading westbound. I explained this above. They will lower the main (east) section of the new bridge after they build it, using large jacks. This will not only bring it to the same level as the old steel bridge (it's a center-track platform and therefore the two tracks need to be at the same height) but also to the same level as the short section to the west of the column, which is currently 5 ft lower. The only reason this is being done so is because the old steel bridge has only 15 ft clearance. With the falsework below the new bridge, it would come down to only 10 ft clearance if they didn't construct it 5 ft higher. Then people's SUVs would hit the falsework. Motor Ave and Sawtelle Blvd bridges will also be built higher and then lowered into place with jacks, just like the Palms bridge.
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Post by roadtrainer on Mar 23, 2013 19:19:53 GMT -8
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Post by roadtrainer on Mar 24, 2013 6:47:20 GMT -8
any body notice that when you want to use the spell check, that it takes you to a web seach site? So I am unable to spell check so please excuse the sloopy grammaer.
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Post by roadtrainer on Mar 24, 2013 7:14:25 GMT -8
National/Venice has been restriped cutting out one lane, confusing drivers who are drivinng through the new no drive zone.(including me who ran out of lane. so one left lane for National, one left turn lane for Venice and one right turn lane for Venice... To keep people out of that closed lane they need K-rail . Not a good idea to close a lane at the freeway exit. Talk about a headache for the next year or so!
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Post by darrell on Mar 24, 2013 22:18:21 GMT -8
New photos from this afternoon... A different view looking up Cloverfield Blvd. Falsework supports on both sides of Olympic Blvd. Falsework spanning Sepulveda Blvd. Soundwall supports east of Military Ave. Big stack of rails east of Westwood Blvd.! The ductbank's six plastic conduits are visible below the slurry-filled trench, looking north from the pedestrian bridge Looking south Wide view of the National Blvd. bridge's forms so far Detail of the pipes to hold the tension cables Looking at the west end you see the old steel plate-girder bridge on the left View from the street Power line work by the new abutment west of Venice Blvd. - half-closed on a Sunday afternoon
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Post by Gokhan on Mar 25, 2013 12:21:46 GMT -8
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Post by rubbertoe on Mar 25, 2013 12:43:41 GMT -8
Gokhan, That second picture from the bottom shows that corner we were wondering about earlier. It looks like the K-rail has indeed been pushed pretty far into the street. There are also a bunch of guys hanging out right there too. The birds eye pics from later will be much appreciated. Unless Dwight beats you to it RT P.S. Also thanks to Darrell for yesterdays pics. A different perspective from a lot of Dwight's.
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Post by Gokhan on Mar 25, 2013 12:50:42 GMT -8
Unless Dwight beats you to it Ha-ha. I was going to take the picture but the train was already closing its doors when I barely made it to the platform. The operator was kind enough to reopen them when I waived at him. I need to take the train back home. expolinefan is probably working at a TV transmitter on top of a mountain somewhere right now.
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Post by Gokhan on Mar 25, 2013 18:10:55 GMT -8
Here are the bird's-eye views of Venice/Robertson, looking straight ahead from the current end of the bridge. You can see the locations of the two columns, in the median and in the southwest corner. Street view of the southwest corner: Looking east from Bagley Avenue. This was Balfour Beatty Infrastructure staging area but they are now in the process of moving out and handing it over to Skanska/Rados, which should take place in a week or two. Balfour Beatty's new staging area will be the southeast corner of Venice/Robertson/Exposition immediately adjacent to the station (partially seen in the first picture). Balfour Beatty will only build the bridge structure. Skanska Rados will build the MSE walls and the right-of-way section west of the abutment as well as all trackwork, electrical work, OCS, etc., including on the bridge:
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Post by bobdavis on Mar 25, 2013 18:20:03 GMT -8
Thanks for the advisory on Venice Blvd. I sometimes get off I-10 and go along Venice to Sepulveda to reach the Cinema Bar when my favorite band is playing there--looks like it's time to take the long way around via I-10 to the 405.
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Post by Gokhan on Mar 27, 2013 15:26:56 GMT -8
This is so major that they have even made an official Web site for the Expo Venice bridge construction: www.expovenice.org/
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Post by Gokhan on Mar 28, 2013 11:31:02 GMT -8
The Culver City skyline was much different today: The station canopies are about 40 ft from the ground. You can estimate the height of the giant crane from that. I am conservatively estimating it to be 120 ft -- 12 stories. These containers will store various fluids used in the drilling of the 100-plus-feet-deep holes: Meanwhile TPSS work at Clarington Avenue and National Blvd, slightly west of the Palms Station, is taking place. They acquired roughly half of the parcel there and you can see the edge of the building on the west side (right side), which is some manufacturing shop, remaining. expolinefan also posted new pics of the construction and alerted us on the construction of the TPSS at Overland Ave and Exposition Blvd: Newest construction pictures by expolinefan: www.flickr.com/photos/expoline-part-2/
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Post by rubbertoe on Mar 29, 2013 7:36:13 GMT -8
I was looking through Dwight's recent set of pictures and had a question about one of them. The shot was of one of the larger column base areas. Normally they just drill and put the 30-40 CIDH holes in the ground, and there is maybe a 4' deep square hole in the ground where this is done. Then they fill the hole with rebar and pour the column base right on top of the CIDH columns.
In one particular shot, the base was so large and deep, they had to surround it with the steel I beams pounded into the ground, which were spaced about 3-4 feet apart. Then they had steel plates between the I beams holding the surrounding dirt back. After the large column base is poured, would then then remove the steel plates, and also the I beams?
I know that in places like National-Palms where they use the same kind of thing to separate say the track ROW from the very close freeway at two different elevations, I am assuming that they leave all those in place. Anybody know?
RT
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Post by rubbertoe on Mar 29, 2013 7:46:07 GMT -8
Here is the site in question, I'll take the picture down if Dwight has a problem with my posting it. I included his copyright infor at the bottom...
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Post by Gokhan on Mar 29, 2013 10:02:53 GMT -8
I was looking through Dwight's recent set of pictures and had a question about one of them. The shot was of one of the larger column base areas. Normally they just drill and put the 30-40 CIDH holes in the ground, and there is maybe a 4' deep square hole in the ground where this is done. Then they fill the hole with rebar and pour the column base right on top of the CIDH columns. In one particular shot, the base was so large and deep, they had to surround it with the steel I beams pounded into the ground, which were spaced about 3-4 feet apart. Then they had steel plates between the I beams holding the surrounding dirt back. After the large column base is poured, would then then remove the steel plates, and also the I beams? I know that in places like National-Palms where they use the same kind of thing to separate say the track ROW from the very close freeway at two different elevations, I am assuming that they leave all those in place. Anybody know? RT This is called "shoring." Shoring is a type of falsework. (Falsework means a temporary structure for support used during construction.) The beams and plates are all temporary, not part of a permanent structure, to be all removed. It's only to temporarily stabilize the earth around the hole so that it doesn't collapse, which could be very dangerous if it did, especially so if someone is inside the hole. Once the structure is built inside the hole, the steel plates and I beams are all removed. If the hole is too deep, they may also need to use horizontal beams from one side to the other, additionally supporting the vertical beams and plates. For some smaller holes, they can also use open-ended steel boxes for shoring.
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Post by Gokhan on Mar 29, 2013 10:14:31 GMT -8
The subcontractor Anderson (not Malcolm of Phase 1) have brought their drill and drilling hardware to the Balfour Beatty staging area at the end of the line. You can see the drill and drill shaft in the first picture and the drill bit (the large, rusty drumlike object on the left, with the augerlike bit probably to be attached in front of it) in the second picture. In the second picture, you can also see the shiny cylindrical concrete forms, which appear to be at least 10 ft or so in diameter. expolinefan has learned that the drilling will start tonight at 9:00 pm.
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Post by darrell on Mar 29, 2013 11:02:33 GMT -8
Love the photo - view from existing station to west abutment, through the crane, showing drill bit and cylinders, local context, nicely lit!
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Post by darrell on Mar 29, 2013 11:08:50 GMT -8
Here is the site in question, I'll take the picture down if Dwight has a problem with my posting it. I included his copyright infor at the bottom... Here are two of mine that show the (same, I think) hole with shoring before and after it was filled with rebar. I'd really wanted to see how the smaller CIDH piles were connected to support the above-ground column; I happened upon this convenient location by Pico at just the right time.
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Post by Gokhan on Mar 29, 2013 11:13:20 GMT -8
Love the photo - view from existing station to west abutment, through the crane, showing drill bit and cylinders, local context, nicely lit! Thanks, Darrell. All with a smartphone (HTC One X) camera. I've been feeling really guilty about not using a real camera much anymore.
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Post by darrell on Mar 29, 2013 12:01:12 GMT -8
Love the photo - view from existing station to west abutment, through the crane, showing drill bit and cylinders, local context, nicely lit! Thanks, Darrell. All with a smartphone (HTC One X) camera. I've been feeling really guilty about not using a real camera much anymore. Definitely better sharpness than my iPhone 4S camera. You see the difference between those photos and my usual Canon T2i DSLR. Plus I get good zooms on the latter.
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Post by Gokhan on Mar 29, 2013 13:09:04 GMT -8
Definitely better sharpness than my iPhone 4S camera. You see the difference between those photos and my usual Canon T2i DSLR. Plus I get good zooms on the latter. Smartphone cameras have been improving with every iteration. iPhone 5 camera is much better than the iPhone 4S camera. The upcoming HTC One (not last year's One X) camera is supposed to be really good. It will be using the so-called ultrapixel technology, which folds every square of 2 x 2 megapixels into one ultrapixel. One thing I had never realized about digital cameras is that a 16-megapixel camera is actually 4 screen megapixels. Because the megapixels don't have their individual color subpixels. In a 2 by 2 square of megapixels, they use one for red, two for green, and one for blue, effectively reducing the number of megapixels by a factor 4. So, If you have a 16 MP camera, it's actually 4 MP on a computer screen. I had always wondered why all digital pictures appear awfully grainy when you view them at 100% full zoom. Now, I know why. Anyway, HTC One is the first digital camera to turn this into an advantage by not having all pixels separately in an image but to combine 2 by 2 square pixels into one, which is increasing light input by a factor of 4... The resulting images seem to be very impressive.
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Post by Gokhan on Mar 29, 2013 16:35:24 GMT -8
In the second picture, you can also see the shiny cylindrical concrete forms, which appear to be at least 10 ft or so in diameter. expolinefan has learned that the drilling will start tonight at 9:00 pm. Form the people standing next to it, the diameter of the cylinder is 12 ft. Therefore, the CIDH (cast-in-drilled-hole) pile will be 12 ft in diameter -- a whole traffic lane! The depth should be about 120 ft. Note that the column above ground will be smaller in diameter. 12 ft in diameter is the foundation below ground. expolinefan will be on site tonight, shooting a video of the drilling action.
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Post by rubbertoe on Mar 29, 2013 17:54:41 GMT -8
I take it they are drilling the corner tonight, then the one that goes in the middle of Venice some other day? Should make a nice video if shot from the platform. Hopefully he will be live streaming it in 1080p HD RT
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Post by bobdavis on Mar 29, 2013 18:23:24 GMT -8
That is some righteous rebar! Last time I saw a construction like that was at a hotel site in San Francisco, where they have a lot of respect for earthquakes.
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Post by darrell on Mar 30, 2013 12:58:22 GMT -8
Dwight posted photos of preparing for drilling bent 16L last night and did this map showing the bent (column) locations along the two single-track beams from the Culver City station to the abutment on the west side of Venice Blvd.
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Post by Gokhan on Mar 30, 2013 14:16:51 GMT -8
Around 2:30 am last night, I was driving by and they were already drilling the hole for one of the supports (bents) -- either 16L or 16R -- inside the BBII (Balfour Beatty Infrastructure, Inc) staging area. They seemed to have gone quite deep already. It takes up to two days to drill one hole.
I said 12 ft in diameter yesterday but the hole could be 15 ft in diameter. Some of the Culver City holes were 15 ft in diameter in Phase 1.
I've got some nice daylight videos of the Culver City drilling action from Phase 1:
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Post by Gokhan on Mar 30, 2013 14:45:06 GMT -8
The drilling subcontractor is Anderson Drilling this time (not Malcolm as in Phase 1) and they are using one of their SoilMec drill rigs, perhaps SoilMec SM400. expolinefan could find out next time exactly which drill rig is being used. Here is the Web site for Anderson Drilling.
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