Dik

Point of minimum moment is likely about mid height of the column; it's not generally convenient to splice at that level.

I do that occasionally, else we have a prescribed partition load. If you base it on actual calculations, you have to stipulate this and that partition layout cannot be changed except yby a prof engineer. In addition. When it comes to actual calculation of partition loads, make sure you subtract the design floor live load for the area taken by the partitions. dik

I'm not sure what a lap zone is... is this a splice location? If so, in these environs, splices generally occur at finished floor level in multi storey concrete buildings. For steel buildings I put them about 2' (600mm) above finished floor.

He's unable to comment; he cannot determine the cause. Back to 'trial and error'.

Thanks... will see if I get any info back; I was waiting for approval.

I'm not a materials guy, but can I share this with someone that is. He may be able to offer a suggestion.

Ignore... I misunderstood your reply Limited... but glad to help... you're coming into your summer and we are starting our winter. For the different types, the first column is the cement type (General Use Portland Cement that may be blended) The second column is the strength in MPa, The third column is the aggregate size, the fourth column is the slump and the fifth column is the air entrainment. I'll try do dig up some info on CLSM; this is a mix design for ultra low concrete strength used for fill or backfill against walls to minimise lateral loads, etc. The trial mix proportions are from my drawing notes for specifying it.

Tayloring mix designs is a complicated task. Even readymix suppliers sometimes have difficulties preparing a batch, and there may be a lot of trial and error in preparing a mix. You might reach out to someone that specialises in this work and see if they can provide some guidance.

You may have to try a couple of batches to get the right mix. If you have a readymix supplier, they may be able to help (maybe not if you are a readymix supplier). There may be a concrete lab in your area that may be able to assist. I ran into some hiccups about 50 years back when I inadvertently specified some CMUs that were about 1000 psi above normal (out of ignorance) but they were able do provide the material.

Nice article... thanks, Dik

What are the issues? and lightweight mortar, or concrete masonry units? I've not encountered lightweight mortar.

I've attached a file with HC details from the past. I do not recall the source. They are in AutoCAD/Bricscad *.dwg format. I couldn't find the ones I drew up... it's been nearly 30 years since I've used them. I've done nearly 20 storey high HC with concrete masonry unit buildings as well as reinforced concrete. It's common construction in these areas. Load bearing brick is not common, here. I've never used Staad... Hollow Core.7z Cv_dik_23-02-20.pdf

I don't know where the negative comes from, but torsional shear occurs when a rectangular concrete beam is subject to torsion. It's the shearing force in the concrete caused by the reaction to the torisonal load. Most current codes address this. Depending on the torsion, the stresses can be fairly high. The stresses are in addition to those caused by actual shear. When I first started engineering, other than the Russians, there was very little information about the design for this. The ACI at the time only had a reference that this had to be addressed. I did my thesis on propagation of cracking in torsionally loaded beams.

Can you cast a 'hairpin' into the masonry wall at the hollowcore joint locations and use a 180deg hooked bar grouted into the hollowcore joint? or even hook the 180 bar around vertical steel in the wall?

Can I get you to re-send the canopy files?