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The footing needs to be embedded to prevent scour and would like to maintain the surficial rock structure in tact as much as practicable. The deeper the better, but it looks like spread footings will be selected. I was more or less writing in this forum, because I thought someone might have...

I think in this case, although not stated in the reports, damage to the rock stucture should be avoided. Definitely no blasting, would the Hoe rams have negative effects on suf-footing structure? The caisson sounds interesting, that was more or less a passing thought--I was thinking end...

"metavolcanic rock with occasional fracured zones" Spread footings are to be embedded in the rock. I haven't seen this before, how are excavations in rock done? Is it practicable to bore holes in rock, for end bearing caissons? Thanks.

First, the original post meant 0.75 f's. Second, did Qshake read the post correctly? The limit on fs is the allowable stress of the cable. Third, steel and concrete are pretty much the same, yet the code changes continually. Would someone please straighten this out. The thread is confusing...

Thanx Old Bean. How about a recommendation for influence lines? Something with influence lines for haunched or parabolic girders. That is a great idea posting as a pdf. I never know what books to buy, bridge books are so far and few between, and buying sight unseen is tough. Thanx, thanx...

Is the 5.25" for your MCE? I agree with the Mecha above, no way. Seismic isolation refers to energy dissipation, I think? Sounds like you need a bridge engineer, not an internet forum.

"Structures shall be proportioned for the following loads and forces: a) Dead Load. b) Live load. c) Impact or dynamic effect of the live load. d) Lateral forces. e) Other forces, when they exist as follows: Longitudinal force, centrifugal force, and thermal forces. Members shall be...

Yes, here it is, http://www.civeng.carleton.ca/Exhibits/Quebec_Bridge/intro.html Apparently, "built-up" columns may be approximately analyzed as homogeneous columns, but the shear effect causes the above to happen, which in standard formulae is neglected. The bridge at the time was to be the...

Here's a vague recollection: Wasn't a famous bridge collapse around the turn of the century during erection in Canada the result of said buckling? Wasn't the cause the neglect of global shear deformation (Essinger's equation)? Sorry no time to research and see if memory serves correct--have to...

Qshake, I've seen a lot of CIP Prestressed boxes built in the 80's and 90's over waterways and highways. Caltrans shows the CIP box as cheaper than the prestressed. http://www.dot.ca.gov/hq/esc/estimates/ I would think the box would also have certain advantages for skewed and curved...

The water slow moving and is 4 ft deep and the soffit is 20 ft up from the stream bed at the center pier. The proposed bridge is 220 ft long and 2 spans. 1) When it goes to bid, how much will the costs of erecting the falsework play in the cost? It seems like at water crossings, that this...

Ok Gentlemen, I'm not talking about free board. I'm thinking of the old Railroad bridges, the kind with the concrete pier walls, the channel was analyzed assuming the the pier width plus 18" on each side of the pier and after a big storm the piers are vertical so there is indeed a big pile of...

1) For the old-time hydraulic calc's: was it 1 foot neglected on each side of the pier to account for debris buildup, was it 18 inches?? 2) What is the reason for greasing the top of an elastomeric bearing and installing a smooth plate above it: It's not a sliding bearing it's supposed to...

These sound like excuses for a broken a system: 1) Most bridges that were designed for H15 carry todays trucks, including permit loads. 2) Many old bridge rails have functioned for 75 years, and have functioned under today's pedestrians and vehicles. 3) The funding system does not promote...

Does anyone think it has to do with the increase of standards and codes. Bridge rails get aesthetically displeasing by the year. Concrete box girders are one too many. It's a shame a lot of money is spent, but nothing different is allowed.

What about other types of plastics and composite type pipes? It seems like there is stigma against plastic. Would plastic be alright if it was inside a carrier pipe, thus it would have room to expand and contract? I for one would really appreciate some more explanations and comments on this...