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Wouldn't each grout each lift interface represent a construction joint in the wall? Wouldn't you want to make sure you are developing the vertical reinforcing at the top and bottom of each grout lift/construction joint to maintain continuity in the wall?

I have a project where I am using #6 and #7 rebar for an 8" CMU wall. The design code is 2006 IBC and the required masonry rebar lap splice length is 72db due to the stress in the bars. So for a #6 and #7 bar, the required lap splice length is 54" and 63", respectively. The masonry contractor...

Are there any code provision that require ductile failure modes for cast-in anchors in CMU in high seismic areas? For example with concrete, ACI appendix D clearly outlines the requirement that ductile failure modes must govern anchorage design in SDC C or higher structures or that you can...

12.10.2.1 Collector Elements Requiring Load Combinations with Overstrength Factor for Seismic Design Categories C through F. In structures assigned to Seismic Design Category C, D, E, or F, collector elements (see Fig. 12.10-l), splices, and their connections to resisting elements shall resist...

I am designing an occupancy category IV structure that is in a seismic design category of D. The structure is steel bar joists on CMU bearing-shear walls. Where the joists bear on top of the CMU walls, to transfer the diaphragm load to the top of the wall, I am debating whether to use tube...

I agree that is probably the main mechanism for what we are calling "suction".

I still don't follow the whole concept of "no suction"; there is documented evidence of tornado's (albeit extremely rare, violent ones) that have caused ground scouring and peeling off of road pavements. Kootk, what's your thoughts on threading the topping reinforcement through embedded...

Why wouldn't there be suction at the roof of a 22' tall storm shelter under 250mph, partially enclosed wind loads?

dik: That is an option but we usually prefer the topping slab to give the precaster the option to design as composite and I like to use the topping as a diaphragm. What is the methodology of using the inserts? Are you assuming the inserts are the support points for the slab by anchoring the...

I'm designing a storm shelter where the gross wind uplift is on the order of 225 psf. We will be utilizing either precast hollowcore planks or double tees as the roof system with a 4" topping to resist in-plane diaphragm forces. How is the topping slab anchored to the roof members for net...

The geotech report states that the long-term groundwater level is anticipated to be at or below the explored depth (14' below existing grade). The geotech engineer for the project stated that in his opinion he would not design the foundations for buoyancy loads and tornado loads at the same...

For the dead load only load case, the buoyancy uplift is not giving me any stability issues. It is the .6D +.6W + H (where H is the uplift due to buoyancy) load case that is giving me issues where the footing is subjected to overturning from in-plane shearwall loads. The buoyancy uplift...

Section 303.3 of the ICC500 states: "Underground portions of storm shelters shall be designed for buoyancy forces and hydrostatic loads assuming that the ground water level is at the surface of the ground at the entrance to the storm shelter, unless adequate drainage is available to justify...

EZbuilding, could you elaborate on this? I use shear friction all the time for these connx for cast-in-place walls for storm shelters.

That is what I am thinking about doing (using the provisions for concrete) however I am unsure if I should do this as my calcs will have a 3rd party reviewer and I would hate for this to be an issue during that stage of the project.

How would one go about designing a reinforced concrete slab-to-top of cmu wall connection in the attached sketch? What provisions in the masonry code would you use in designing the 90 degree rebar dowel attachment for the forces shown? This connection is for a storm shelter. I only have...

I am calculating the wind load on individual members for an exterior steel frame (open building). Using ASCE 7-05 section 6.5.15 "design wind loads on other structures," does the force coefficients include the windward and leeward wind against the face of an individual member?

JAE, To calculate the natural period of this frame I used the formula T = 2*Pi*SQRT.(m/k) where m is the weight (assumed to be lumped at the top of the frame) and k is the stiffness of the frame (which I calculated by applying a "dummy" load and seeing how much the frame would deflect). Do you...

I am trying to calculate the gust effect factor for a four-legged exterior steel portal frame that supports a large piece of mechanical equipment. The frame consists of steel moment frames in each orthogonal direction (directly welded flanges at HSS tubes) and has bolted shear connections at...

I have a two story building. The interior partition walls at the ground level and upper level are all metal stud walls with deflection tracks up to the joists/beams above each level. When calculating the effective seismic weight at the upper level, I know the code mandates that you add 10...