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Thanks for the answers. I plowed through the design. As typical the real world problem was much more involved than the simple example. Is there a consensus that the Malone approach is conservative compared with FEA?

I have to design my first irregular diaphragm and have been going through Terry Malone's example in "The Analysis of Irregular Shaped Diaphragms" from WoodWorks. (Attached) I think I am getting it. Seems like a series of FBD's and superimposing them(?). The thing I don't get is where the 20'...

In ASCE 7 the figures show a uniform suction on the leeward walls. It feels like this is a simplification and the suction would tend toward to 0 at the middle of the wall length (and mid-height for wind over the roof). Does this make sense or is the suction really uniform over the length of...

Thanks for the response.

Two questions for detailing construction of shear walls: The edge nail spacing is tight (2 or 3 inches) so at a panel joint 2 studs are used with each panel attaching to its own stud. Are the studs connected? It seems like this would be slip plane if not. What force is used to design the...

phamENG The LRFD equation is (Load Factors)x(Driving Forces) < (Capacity Reduction Factor)x(Resistance). The left hand side comes from the combos - 1.2D+1.6L etc. The capacity reduction factor or phi factor comes from a code - AISC has 0.9 for shear unless a listed I-shaped member with a...

Assume for the shear wall the uplift is W=1000# and the weight of the concrete footing at the end of the shear wall is D=1000#. Using 0.9D+1.0W the net uplift is 100#. That is the factored load. The resisting force is the dead load of 1000# or is it 0? Should I think of the equation as 1.0W is...

I am designing a shear wall and want the weight of concrete foundation to resist the uplift. I am thinking LRFD might work better than ASD - 0.9D+1.0W vs. 0.6D+0.6W. But if I use LRFD what would the phi factor for uplift be? (The equivalent to phi = 0.9 for a beam using 1.2D+1.6L). For ASD, is...

OK. I now see there is no rotation of the foundation resulting in uniform bearing pressure. Shouldn't the reaction at the top (and bottom) be different than for a propped cantilever? I am still not seeing how there is equilibrium. Thanks

I am not following. Are you saying this is what the freebody diagram would look like? The 448.96# is close to the 450# expected for a propped cantilever. If I cut a section where the wall meets the footing there needs to be a moment of 3000#-ft for the upper reaction to be 450#. Wouldn't this...

I have been modeling restrained retaining walls in EnerCalc with the attached geometry. (I hope I uploaded the figures correctly.) EnerCalc has two options - one where the wall is pinned-pinned and another where the wall is fixed-pinned (fixed at the footing). When I run the model as...

I am putting together a reinforcement schedule for residential foundation walls. I decided to check my designs against the tables in ACI 332 to see if I needed to do my own calculations or just use ACI 332. I have checked several entries on Table 8.2.1.3d for 3000 psi concrete and 60000 psi...

Thanks JoelTXCive and retired13. In the fifteenth edition the text JoelTXCive posted is split between page 10-7 (with Figure 10-3) and 10-91. I am not thinking about rotation in the plane but preventing rotation about the longitudinal axis at the ends for LTB.

Thanks I am using the geometries shown in the Table 10-10 form the steel manual. I guess what I am asking is should I use 3 bolts to get the plate length more than 1/2 the beam depth even though 2 bolts has sufficient strength? You say to add more bolts but how many to get a plate length that...

I am designing single plate shear connections and wonder if there is a rule for the minimum length of the plate vs beam depth. For example a 2 bolt connection may have adequate capacity to support a W16 beam but the plate is only 5 1/2" long or about 1/3 of the 16" beam depth. Is that...

Thanks. That helps some.

I am doing residential wood design for a project in another state and am trying to find out what species and grade of wood is typically stocked and sold to contractors. Is there a survey or something that lists this? (I think AISC does a survey to find out what grades and shapes of steel are...

I often have to design residential basement concrete walls that are taller than 10 feet. The way I read the IRC and ACI 332, those codes only apply to walls less than 10 feet and ACI 318 has to be used if the wall is taller. ACI 318 has minimum reinforcement requirements for both vertical and...