I know that connecting dissimilar metals is not recommended. I've looked at galvanic corrosion charts, but I've had a hard time making good sense out of some of the tables I've seen. My specific question is about these connections:
1. stainless steel to galvanized steel
2. aluminum to...
Does anyone know if there are design examples and/or other information somewhere out there for a curved steel girder bridge with an integral post-tensioned concrete pier cap?
I'm working on a bridge where we will most likely be utilizing that kind of system. I've done PT pier caps before, just...
I am working on designing a pedestrian bridge based on the new AASHTO LRFD standards. According to section 3.6.1.6, the fundamental frquency of my bridge has to be higher than 3 Hz. I am having a hard time making this work and it's going to cause me to have a really deep section, almost to the...
I have a road/bridge project that I am working on where we have a 36" diameter concrete pipe that was covered with 6.5' of fill. After the project is done, the pipe will be ocvered with 24' of fill in some spots. The pipe can't handle that amount of fill, so we will need to protect the pipe in...
Does anyone out there have experience with designing reatining walls with clay backfill. I have a situation where I need to evaluate an existing wall. I have never designed one with clay backfill (only sand). The material that I have gives 2 methods. The vertical reinforcing in the wall...
I am working on a project where the client has an existing retaining wall that needs to be raised a couple of feet. The wall is holding back an earthen dam. The problem is that when I analyzed the existing wall with 2 additional feet of height, the bending moment capacity at the base of the...
I have a questions regarding water pump station design. I have a 25' diameter pump station with 3 submersible pumps.
On rectangular pump stations that I have seen, there are divider walls/hydraulic separation walls between the pumps, I'm assuming to avoid cavitation type issues. Are these...
I'm designing a bridge abutment at the edge of a river and wanted to know how to handle the fact that the footing will be below the water table.
The wall is a cantilever abutment retaining wall on piles. The top of the footing is at elevation 773.00. The footing is 3' thick. The water table...
I am working on a bridge where I have a full height "retaining wall" abutment supported on piles. My question is really on the wingwalls for these abutments. Because of some utilities in the area that cannot be moved, it will be difficult to have the wingwalls supported on piles.
I was...
I'm looking for cross sectional properties on an old steel channel (for a bridge built in 1924) that was 15" deep and weighed 55 pounds/foot. Anyone have any ideas where I might find this information? I have an old publication that has wide flange shapes, but no channels. If nothing else, I...
I have a question on post embedment in a concrete drilled shaft/caisson.
I am doing a soundwall design where the soundwall posts are prestressed concrete in the shape of an "I". The panels are also prestressed concrete.
We are trying to calculate how far to embed the soundwall posts into the...
Is anyone familiar with Section 5.14.1.4.2 in the AASHTO LRFD code? Bascially the code says that longitudinal reinforcement that contributes to making a precast girder continuous over a pier should be anchored in regions of the slab that can be shown to be crack-free at strength limit states...
I have something that occurred in Excel that has never happened to me before. I went to Tools --> Formula Auditing --> Trace Dependents to see if any cells referenced cell E24 in my spreadsheet. A box popped up that said "The Trace Dependents command found no formulas that refer to the active...
I have been asked by the site civil engineer on a project that our office is working on to design something called a seatwall. Basically what it is (from existing details) is a 16" wide retaining wall that extends 3'-6" below grade on the low side of the wall. The difference in grades that I...
Anyone aware of any design examples out there for a bridge deck overhang with a concrete and metal railing or metal railing per the new AASHTO LRFD specification, particularly the Appendix in chapter 13?
Everything that I can find is for a concrete parapet railing. I have a pretty good handle...
I am working on a pump station project where the pumps are being replaced and as a result there are some minor structural modifications being done.
One of the modifications that we are doing is "filling in" an existing 16" diamter hole in a 12" thick concrete wall. There used to be an outlet...
Has anyone out there been involved in the construction of inverted-tee bridge pier caps? Our firm is working on a job with inverted-tee pier caps and the contractor wants to pour the cap in 2 pieces - one piece being the "ledge" and the other being the "stem".
We are really hesitant to have a...
I need help interpreting a formula in Roark's book. On page 472, Table 26, case 11d, the formula for the maximum stress contains a variable "q".
My question is: For the triangular loading shown in the diagram, what is "q"? The total load on the plate? The maximum load at the base of the...
I have a design question with a post-tensioned pier cap that I was hoping to get some help with. We are designing a post-tensioned pier cap that has two supports. My colleague and I have designed it two different ways as a matter of QA/QC and I wanted some other opinions on the methodology...
