No prod-rates in the forum

Stevan:



First of all, sorry for the delay in answering your message. It might be too late; but here it goes.



I am not experienced on the exact situation you mentioned. but I can comment on all your questions.



1.- Regarding production rates there is variation in the way things are done and the local expertise available; and in this case, the amount of formwork pre-fabrication. Also, I am thinking about built-up wood formwork. Having said that, 1 mhr/m2 seems to be a good, efficient rate (upper limit).



2.- The sequence shown is not clear: is it formwork-reinforcement as a FF+2 link? Or formwork reinforcement - formwork concrete as a FF+2 link? Any way, I think the sequence is straightforward: formwork-reinforcement-concrete-stripping. When I overlap activities like in your case, I generally include FF relationships as well as SS relationships. In some cases you might do without; but, the the truth is that that is not the way things really happen. You are saying that you can finish placing rebar 2 days after finishing placing formwork. But also, you cannot start placing rebar unless you have some formwork in place. Your activities might be scheduled on the right dates in your initial plan because your durations allowed it. But, your start float is not correct. If you happen to have a shorter duration for your formwork than for your rebar, your rebar activity will start before your formwork starts. If you happen to use a scheduling option like interruptible duration, you are going to get a funny schedule.



3.- Activity durations? Well, this is a case of coordination among several scheduling elements: the scope of your activities, number of crews working on each activity, crew rate, consistency with overall project duration, type of construction equipment and technology used. The first decision I generally do is define the scope of my activities. And this is largely dependent on how I am going to pour concrete. Am I going to have several pour jobs, or am I going to pour all my zone or section or elements in one pour job? I generally define the scope of my activities by the size of the individual concrete pours. If you do it otherwise, it might be dificult to represent how activities really happen on the jobsite. It seems to me that your schedule is going to show your concrete pour at the end of your activities chain. On the other hand, if you have one activity for all your concrete pours that starts after some of the formwork and rebar is in place, you will not have a good concrete pour schedule, which is something everybody will ask for. Once you define the size or scope of your activities, durations are a matter of playing with number of crews, production rates and activity duration consistent with project duration.



4.- If you have enough float in your core walls you might want to go for common formwork. You also need to consider the availability of equipment and expertise in the case of using a hydraulic climbing system. And cost if you are going to use it just for 4 levels.



5.- I do not understand what you mean by "method statement for walls (their preforming)" But I think I got your idea. It does not really matter whether one element stops and goes on one level at a time or it goes two levels without interruptions. What will matter will be how you link your activities. You can have, for a simpler and orderly schedule, all your walls and columns by level, your links will make the diference. I do not think you are going to pour those columns that run two levels in one concrete pour. So, you should have those columns by level.



6.- You only have 4 underground levels? What about the rest of the building? You are going to use the jump forms just for the substructure? It seems to me the the use of jump forms is not worthwhile for just the substructure. I am not experienced in jump forms (climbing system or slipforms) but they are recommended for walls over 8 stories high. You need a specialty subcontractor for this job. I would recommend to you that you talk to one.



If you have comments or other questions, I promise I will answer promptly.



Tomas Rivera

Altek System

Stevan:



In the mean time your post is properly placed, what are your questions?



Tomas Rivera