I am designing a canal wall using soldier pile with timber lagging. Timber is required due to constraint of being "restoration of historic properties", otherwise I would use concrete lagging. Additionally, I cannot use ANY wood preservatives to treat the timber. The front of the wall will have...
ACI 318 section 11.6.2.2 allows the maximum torsional moment to be permitted to be reduced based on redistribution of internal forces upon cracking (compatibility torsion). AASHTO LRFD does not even discuss compatibility torsion. Any thoughts why?
In a construction sequence where precast stringer beams pass orthogonally thru a cast-in-place supporting girder beam to become an integral assembly, can the stirrups of the precast section be considered stirrups participating in the shear resistance capacity of the girder beam in the region of...
There are many types of tie-back and bonded strand anchor systems available to designers. Without favoritism to any manufacturer, is there a "rule of thumb" for what type works best in various soils: clay, silt, loose sand, compacted sand, gravel, fractured rock, stable rock, etc?
Pre-drilled...
60' x 120' x 25' Steel framed building. MWFRS uses steel braced frames and moment frames with infill walls on two exterior sides, one 60' wall, one 120' wall. Is this building open, partially enclosed, or enclosed? Per ASCE7 definitions:
Open Building: Requires "each" wall must be at least 80%...
Consider a soldier pile retaining wall that uses a waler with a single tieback to support 2 adjacent piles. Traditionally such a tieback would be centered between the piles. However, due to project constraints the tieback needs to be installed off-centered. For example, with a 6ft soldier pile...
If 2 rectangular beam sections of the same material share load effects, moment sharing is distributed by the ratio of respective member stiffness. That is each individual I (moment of inertia) divided by the total or summed moment of inertia. How is shear sharing distributed? Is it by a ratio of...
Driving 24" pipe pile to 850kip ultimate capacity using gates equation. Piles driven open-ended through alluvial gravel with numerous cobbles up to 12 inches in diameter as well as occasional boulders. Pile embeds are going much deeper than expected, 80ft embed estimated, actual 140ft+. SPT...
I recently had a driven pile (PP24.00x0.500 open-ended) that settled 10 inches. Yes, 10 inches, when loaded with a temporary load. Pile was driven to a depth of 120ft achieving 550kips ultimate capacity using the gates equation. Pile log verifies capacity. Maximum load onto pile was 220kips...
Consider a two-span continuous beam (L=span length, 2L=total length) with uniform loading and a axial force along the axis of the beam. The top & bottom flanges have stability bracing at the support locations only. What are the values of Lb(lateral-torsional buckling for bending capacity), and...
I am revisiting a discussion developed in 2001 requesting comments regarding the best option(s) for Bridge design software. A decade has passed since this was last discussed, so maybe someone has a bit more recent feedback.
Original Post:
http://www.eng-tips.com/viewthread.cfm?qid=8303#post...
Question: What is the proper use of Seismic Response Modification Factors:
Option 1:
Response Modification Factor values greater than 1.0 , which are applied to select member effects in recognition of ductility and energy dissipation ability, should only be applied to member moments. R value...
If I have a multi-story light-framed structure constructed above a rigid structure (i.e. an elevated concrete slab with very stiff lateral resistance system below), could I justify considering the “base” to be the top of the elevated concrete slab for measuring the seismic height of the...
I am designing a non-insulated building where standing seam metal roofing is specified. Is a structural sheathing substrate (i.e. plywood or cdx) my only option for developing the roof as a diaphragm, or are there standing seam metal roof products rated to provide shear resistance required for...
I recently designed an aluminum structural frame for a 5’x160’ long pedestrian bridge using various sizes of extruded 6061-T6 aluminum sections. Most connections were aluminum welded. I specified 5356 filler wire and mainly 1/8” fillet welds (which fabrication upsized to 3/16-1/4” nearly...
I am trying to develop the capacity of the roof joists of an existing building located in Oregon. I have the original construction documents dated 1962, and they specify the joists as “18LA 10 STL JOISTS @ 8’-0” O.C.” They span 35’-0”. I know these are not in production anymore, but anyone...
Does anyone know what the minimum roof live load (or snow load) and the minimum floor live load that was required for design of an office building in Oregon back in 1962? I am fairly confident that the applicable code of that time was produced by ICBO for the west coast region of the US, but I...
Lateral analysis - Detailed vs. Simple
When performing the analysis for a Lateral Force Resisting System, typical practice in my office is to calculate both wind and seismic loading conditions for every resisting element independently, then proceed with the design of each element using the...
I have a design where 4 inch joists frame into the backside of a 12 inch deep C-channel. However, the top of the 4inch joists are 2.25 inches below the top of the C-channel (therefore not directly offering support to the top flange). I have opted to put in a flange stiffener at this location...
