Good day all.
Owner is afraid that flood will wash away the embankment, and the stub (perched) abutment will collapse. Abutment is on spread footing with no piles underneath. This has happened to some other bridges (a random example shown below).
So, we are doing a preliminary conceptual...
Sorry BridgeSmith, I don't understand! If the bases of the posts are considered fixed, there will be torsion at the base. This torsion will transfer to the cylindrical foundation. Right?
Let's look at a practical example. We have this large 55.5 m overhead sign. Post height is 9.5 m (average)...
@BridgeSmith
Thank you for taking time in replying in detail. It's CIP. The Code is Canadian. We will not do P-y analysis. We will use Modulus of Subgrade reactions recommended by Geotech to determine soil spring stiffnesses and do the analysis.
You mentioned Torsion is usually not an issue...
Good day all.
We are going to design a cylindrical concrete foundation for a large overhead highway sign structure.
The manufacturer of the sign structure will provide us with the forces and the moments at the top of the foundation. A sample is shown below. Notice the high torsion.
We also...
@ lexpatrie, @ fel3, @ Tomfh
Thank you for your comments. We will see if we can sell the idea of a steel bracket to the owner.
@ TLHS
Very good points about moments and torsion. The load path gets complicated, and developing resisting couples using the dowels may be tricky.
You are right about...
@ CDLD
Thank you. Yes, the dowels will be attached by Hilti adhesive anchor or similar. But I am having difficulties in figuring out the load path, and reinforcement arrangement. If this had been a monolithic construction, I would have used a strut-and-tie model. The light pole (due to wind...
Good day.
We know how to design a corbel in a monolithic construction.
However, my problem is different. We need to design a new corbel that attaches to an existing structure.
As shown below, the new corbel is a light pole base which gets attached to the existing bridge deck. So the...
@ STrctPono
Instead of a truss model, if we use a beam element (or even better -- shell elements) to model the pile cap beam, we might see increased load sharing between the piles. The loads are slightly off the central pile, and the bending rigidity of the cap beam helps to distribute the...
@ STrctPono
Thank you very much for your reply.
Yes, the launching has to be figured out. Crane is a possibility.
We got biased by a design where diagonal stiffeners were used (photo below). We will take a look again. You're correct about load sharing of piles. The middle one in the set of...
@ BridgeSmith
Thank you for pointing out a number of potential issues. We may have to use a custom made cap beam having a wide flange, instead of using a rolled shape. Transvers restraint mechanism is expected to be a part of the pre-fabricated superstructure system (the bolts of the bearing...
@ BridgeSmith
Decked Bulb Tee Girders are certainly good options.
Our project is a bit unusual though. Owner is even ok with a single lane timber deck. This bridge serves just one or two properties across the river. The owner does not have much enthusiasm or funding to build a "regular"...
@ AS_Peng
A pony truss option well exceeded client's budget a few years ago. So they have now resigned to a modular bridge option. In addition to cost, remoteness and cold climate are also factors for the choice of superstructure.
Precast blocks could work as well.
@ LittleInch
It's not a...
@ BridgeSmith
Four deeper piles will require a heavier rig to access this remote site, which may not be possible.
Prefabricated bin-boxes are preferred over MSE wall because the former would be a delegated design to the manufacturer, the same manufacturer that builds the modular bridge panels...
@ BridgeSmith
Thank you very much for your reply.
1. Remoteness and fast approaching winter have made the client opt for a modular bridge for this low traffic volume location. Similar permanent modular bridges were constructed elsewhere.
2. Yes, you are correct. The pile cap could be downsized...
Good day all.
A 32 m long bridge is to be constructed on a rural road over a small river. Sketches of the conceptual design are shown below.
Kindly take a look and advise if this concept looks acceptable. For example, what do you think of using a single row of piles, having no batter, use of a...
Good day all.
Precast traffic barriers will be installed on the bridge deck in a rehabilitation project.
One option is to mount the light poles directly on top of the barrier. An example is shown in the google photo below. The barrier may be TL2 or TL3.
Can someone please direct me to...
Thank you SlideRuleEra for your detailed reply.
I made a mistake in my original sketch. The strong axis should be oriented parallel to the cap, as you indicated.
We have the Geotechnical Report, and the skin friction values are known. We are not relying on end bearing.
We expect the pile cap...
@BridgeSmith
Thank you very much for your reply.
We are concerned about misalignment due to pile or cap installation error (it's a remote location). There might be eccentricity in load P both in longitudinal and transverse directions. We wanted to prevent distortion of both the flange and the...
Good day all.
May be this is a simple question, but we learn by asking those who know.
We are designing a steel foundation for a Bailey type bridge system. This will be a permanent bridge. The foundation consists of three piles (HP 310x 125) at each end of a pile cap (W 1000x295). The Pile cap...
Different Codes try to deal with seismic effects on unequal column heights differently. There will always be discussion whether the Codes can achieve what they wanted to achieve.
There is a paper available online, in case you are interested...
