Multiple Relationships

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来自 Columbia University 的课程

Construction Scheduling

598 个评分

Columbia University

Construction Scheduling

598 个评分

课程 2（共 4 门，Specialization Construction Management）

Learners will discover the key project scheduling techniques and procedures including; how to create a network diagram, how to define the importance of the critical path in a project network, and defining project activities float. Also covered are the fundamentals of Bar Charts, Precedence Diagrams, Activity on Arrow, PERT, Range Estimating, and linear project operations and the line of balance.

从本节课中

Types of Construction Activity Relationships

This module provides an overview of the types of construction activity relationships encountered in a construction project and how to represent them in an activity precedence diagram.

Activities in a Construction Project6:01

Types of Relationships between Construction Activities7:15

Start to Start Relationships7:49

Finish to Finish Relationships4:13

Multiple Relationships3:53

与讲师见面

Ibrahim Odeh, Ph.D., MBA
Instructor, Department of Civil Engineering and Engineering Mechanics, Columbia University
Director of Research and Founder, Global Leaders in Construction Management

For what I want to discuss here,

is what we call a multiple relationships that exist.

The example here, between these two activities of a multiple relationship.

It says here, the first relationship is the start to start relationship,

with the lag equal 1.

After I place the steel, I won't start placing the forms.

So we are starting placing the forms here, the same place in the wall forms.

And one day after I start with the form activity,

I can ask my workers to go up there on the wall,

on the rebars, and start to tie the wall rebars.

So there is a 47.

At day number 47, I'm going to start with this activity.

And after one day, I will ask the workers, on day 48, okay, go up there.

You have now in a forms are on the walls, maybe from one side,

go to the other side, make sure to start tying the wall rebars.

So this is one relationship.

And in addition to that, the other relationship is

a finish to finish relationship, highlighting

that you will need to finish tying the rebar one day

before you finishing replacing the forms on the wall.

So the end day of tying wall

rebar is going to be 54.

But the end day of placing the wall is going to be 55,

because you want also to clear the workers, the labors,

from the wall and make sure, then, to finalize with closing the forms and

tightening the forms to get it ready for the activity of pouring the concrete.

Remember, when I mentioned a lag of minus 1 here, what's that mean?

We referred to a negative lag, as I explained, to a lead.

So instead of lag, then we can have a lead of 1 or a lag of minus 1.

So this is an example I want to highlight here.

Now, this is example of multiple relationships,

two activities they have together.

This is uncommon.

So to sum it up, my suggestion for you, and my recommendation,

is to focus and concentrate, if you are working in a scheduling exercise,

on the first of three types of activity relationships.

Which focusing on finish to start relationship with either a lag equal 0,

which is the traditional relationship, or a lag equal 1 and

more, which is also a very common relationship.

Schedulers usually use it, prefer to use it,

they don't like to go in other than that.

Or to go to finish relationship, with a lag of 0.

But usually, finish to finish relationship, you do have some lag time.

And in addition to that, the start to start relationship with a lag of 0,

or a lag of 1 and more between the activities.

And try, again, to avoid the types of relationships that highlighted

the start to finish, or to highlighted in multiple relationships.

And we will not go deeper or experiment more in our course here.

Thank you.

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