Slickdeals: The structure itself should displace less with soil springs, as the soil will take some of the displacement, and lower seismic loads will be applied. The overall displacement may be greater, but the local displacement (ie. on a column) shouldn't be.
You need to design and model your columns as they actually are - fixed or pinned. This clause is addressing the foundation, meaning the soil. Soil isn't infinitely rigid, and doesn't act like it in an earthquake. But if you assume it's rigid, most likely your structure period will be shorter...
Upon further examination of the code, I realized that the equation they have for the factor of safety is incorrect. I believe when summing forces they considered the weight of the wall as acting upwards instead of downwards, which resulted in the weight of the wall CONTRIBUTING to sliding. I...
Modeling your footing as fixed will result in higher loads on the structure, which is conservative. Using soil springs typically increases your period, so you get lower displacements/loads. ASCE7-05 is essentially asking you to be conservative.
I'm designing cantilever retaining walls per Caltrans BDS, which gives two different methods for calculating sliding resistance when shear keys are present (see attached). The first assumes a horizontal failure plane at the bottom of the key. For this, my sliding FS is OK.
The second method...
If you're looking for a rough cost for typical rebar, our last job was bid at about 70 cents a pound (US). Since I believe the US dollar is slightly higher than the Canadian dollar, you can probably adjust it down slightly.
Samwise, It depends on what code you're using. In California, we design the transverse shear keys to fail under high seismic loads to protect the abutment foundation, so we use a fictitious spring at the abutments in the transverse direction only to prevent any anomalous results in the model. In...
Having designed half a dozen precast girder bridges in California, I can safely say that I have never used the lateral stiffness of the bearing pads for seismic design. Typically the bents have diaphragms and act continuously (modeled as such), and the abutment stiffness is calculated based on...
There's a statement in bridge codes that says slabs designed for moment do not need to be checked for shear. Check your code - guidance should be there.
Something that might work for you -
http://www.con-span.com/CON-SPAN/nof_main.html
They have nice-looking structures that are erected pretty quickly and easily. It might take away some of your "do it yourself" ability, but then again it might not be a bad solution.
I ran the analysis using releases @ 30', and the forces reduced dramatically. The box is OK. I think it's clear that the expansion joints are used for exactly this reason. The only thing left to do now is head to the field and check that the expansion joints actually exist.
Thanks for your help...
Battered piles can be used successfully in service load applications, but not seismic. So if your high load case is service load, I'd say go for it - but if your battered piles end up in tension you might have a problem. To give an example - battered piles are used successfully in port...
The box is standard. I've attached the standard plan from 1966 - as you can see, the longitudinal reinforcement is minimal. The box is a few hundred feet long (under a freeway), and most of it is covered by 14' of fill. The last 50' had minimal fill, and we're filling it to 14'. I don't have a...
Ok, makes sense. I design using AASHTO so I won't be of much help for your fist question.
As far as development into the slab, we usually go to the bottom of the top mat as well. The Port of Los Angeles has developed a detail using short drop-in headed bars lapped with the pile reinforcement...
Battered piles are used for lateral service loads. The piles don't take the load in shear, but in axial load (components). Battered piles tend to behave poorly in seismic events for many reasons, but particularly because battered piles only behave well in compression. Battered piles are used to...
