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BEHAVIOR OF CRITCAL PATH IN VERTICAL STRUCTURE

4 replies [Last post]
Ernesto Montales
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Joined: 23 Mar 2002
Posts: 65
Good day planners,

I have been a planner for a company which specialized in concrete vertical structures usually commercial buildings (malls, highrise residential condominiums & etc..) I have observed that a low rise wide area buildings particularly malls and warehouses the critical path usually lies on the suspended slabs. For highrise building the crital path lies with the vertical elements such as liftwalls columns, RC walls. My question is can we conclude this as fact? Or it has something to do with the methodology?

Regards

Ernesto Montales

Replies

Ernesto Montales
User offline. Last seen 34 weeks 7 hours ago. Offline
Joined: 23 Mar 2002
Posts: 65
Ernesto,

Thanks for you reply. It its now clear to me that the Critical is a result of schedule logic.

Regards


Ernesto Montales
Ernesto Montales
User offline. Last seen 34 weeks 7 hours ago. Offline
Joined: 23 Mar 2002
Posts: 65
David,

Thanks for youre reply. Based on what you have said its a matter of methodology. So its how you allocate resources to the elements on which is economical?

What im trying to say in my previous post is that on the type of structure for example a multi-storey building consisting of 35 floors with a 1,000 sq.m foot print. The critical elements there are columns,walls and lifts. Whereas in a Mall consisting of 3 levels with a foot print of 10,000 sqm the lift there are not anymore critical. The critical part now are the suspended slabs. Can you comment on this.

Regards

Ernesto Montales
David Bordoli
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Joined: 8 Apr 2002
Posts: 416
Hi Ernesto

As a general principle I agree with you but I think that is just as a result of how we put our networks together. In my experience the vertical elements of a building require more resource and there tend to be more individual elements whilst (to generalise) the floor slabs are simpler and are faster, floor-by-floor, than the vertical elements. If we chose to apply disproportionately greater resources to the vertical elements, hence reducing their time if that were possible, then maybe the horizontal elements would be critical – but I doubt this is practical.

Having said that I tend to find both the vertical and horizontal elements are on the critical path. A proportion of the vertical elements having to be complete before the horizontal elements can start and similarly, part of the floor being complete before the next level of vertical elements can start.

This S-S and F-F linkage between the vertical and horizontal (if it were to be scheduled in such a simplistic manner) I don’t believe is capable of being modelled in MS Project.

Regards

David
dbordoli@burofour.co.uk
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Ernesto Puyana
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I think there is not a single right answer to your question. It all depends on contruction systems and methodology. If you look at a concrete wall building (Outinord type forms), walls and slabs are both necesarily critical.

In frame type buildings, I think it depends on the extention of each floor, but from my experience and local construction methods, columns (and walls) are much faster to build than slabs. In a high rise small footprint building, you cast all columns for esach floor in a couple days, while a slabs takes a whole week to finish. In a large footprint, mall stile building, as soon as you cast a first section of a large slab, yuo have space to cast columns on top, but you wonf be able to finish casting those columns until the whole slab is finished.

In the end, the critical path is not the result of a trend or a typical behavior, but the result of a schedule logic. The same activities, with the same duration will yield different critical path depending on the type of relations used. So the correct path can only result from applying de correct relation type, that is the one that best models reality.