I have a somewhat complex steel bridge structure that we are designing. It's tall, has lots of complicated welds, has battered built-up members with braces in two directions. I am considering requiring that the steel fabricator hold an AISC (ABR) Advanced Bridge Fabricator Certification. I...
How can that bridge displace 24"!? Tell the designer to pull his head out of his rear end. Our office always considers soil passive resistance on both integral and semi integral abutment designs. I thought everyone did. That's one of the main benefits from an analysis standpoint. From a...
Not trying to nitpick but you asked for comments. The diagonal stiffener arrangement as shown is doing nothing. If there was to be any load sharing across the piles, the stiffeners should have been inverted the other direction.... but even then it is minimal. I guessed on the aspect ratios, but...
Based on the information you are giving, it sounds like you need to follow civil highway PCC pavement design practice. This is actually pretty specialized design work. FHWA has a lot of good design reference guides on the matter. There are even software programs that will help you do the design...
Thank you all for the responses. Sorry for the bad photo. It was all that was sent to me. This is my design but I showed the rafters at full bearing on the double top plate and notched only for the extension of the rafter into the eave overhang. The house has a transition from rafters/ridge beam...
Bailey bridges are typically launched from one side. This is to avoid needing a large crane (which it sounds like you can't get out there). In order to launch it, you will need a significant backspan on the bridge approach to assemble a portion of the bridge and push it out. If the bridge is...
I'm helping out a friend on their house design and I'm going out tomorrow for an inspection. He sent me some progress photos and I noticed that the carpenters notched the end of the rafters significantly! It looks to be about half the rafter height. They are 2x12 rafters. I checked it and the...
I have a project very similar to this that is ongoing and is also in an isolated tropical location. Looks like the source of your landslide is not just loose debris being carried down the hill in heavy rain... you had a slope stability failure. You would need to either cut back that slope to a...
Thank you everyone! I feared that was going to be the answer. It makes sense, however.
The eave is a 30" overhang. The existing structure has pre-engineered trusses at 2'-0" o.c. on the existing building side and we are stick framing rafters on the new side at 2'-0" o.c.
So is the consensus to...
I've mentioned before that I don't do a lot of wood design and I have always gotten very helpful advice from everyone in the past. For that... I appreciate you all.
For a typical scenario where you would be doing a gable roof extension off of an existing roof with 1/2" plywood. What is the best...
I too apologize for posting that comment. I was rationalizing it incorrectly with a pretensioned element locked off on a rigid body not part of the system. If the pretensioning force were locked off at one of the nodes of the braced frame then statics would tell you that the additional stress in...
Thanks azcat. I learned something new today.
I may be misunderstanding you but I don't see the pre-tensioning force reducing the ultimate strength of the brace. I think of it like this. A brace member pre-tensioned to 50 kips would see no additional stress from an externally applied load...
Agreed with everyone else. Your translational restraints should be as follows:
Node 4: Rx, Ry, Rz
Nodes 1 and 5: Rx, Rz
Node 3: Ry, Rz
Nodes 2 and 6: Rz
I was part of a pre-engineered steel building project almost exactly like the one you posted several years back. The manufacturer never pre-tensioned the threaded rod lateral bracing. They just snug tightened it and had a note on their drawings that the building owner would need to come back in...
BigH. Good technical article. I was aware that FHWA/CFL was very keen on using rockery design in Colorado.
EireChch, I always assume that the wall is one rigid body with composite action between the rocks and mortar. From there it's essentially a stress check based on the thickness of the wall...
I recommend you talk to a senior level Engineer in your office to help guide you on running a response spectrum analysis.
Either way, the idea is to reduce your lateral demand on your structure based on the understanding that you will have an inelastic response from your structure's lateral...
You can have a good idea where the initial and any secondary hinging might occur from your elastic analysis but you won't know for sure unless you run a pushover. The standard method would be to run your elastic dynamic analysis and then reduce your response spectrum by a seismic response...
I was referring to your comment on joint in railings/parapets on bridges. We call those deflection joints. They contain a gap. No joint filler. Chamfered edges. No dowels or keyway.
Interesting detail on the deck joints. I've never seen that.
mad2323, I think everyone believed that you were going to assess an existing wall... not design a new one. I for one have no issues with grouted rock walls. I have designed many before and they are commonly built in my location. We are not allowed to use them to support bridge structures (for...
