Tuesday, September 7, 2010

Concrete vibration is important

Vibrating concrete is a must so that concrete can achieve its design properties

Vibrating concrete makes it more fluid and hence it flows into the corners of the formwork

Air-gaps in concrete are significantly reduced and results in a more consistent density of concrete both at top and bottom

However over-vibrating the concrete will result in seggregation of aggregates.

One must be careful that vibrator does not disturb the rebar arrangements especially in areas where rebars are very dense.

For optimum compaction the frequency of the vibrator should be between 10,000 to 12,000 vibrations per minute.

What is BIM and 3D, 4D and 5D ?

Building Information Modeling is the process of converting the 2D drawings into a 3D model on the computer. The structural, architectural and mep drawings are used as inputs to create an very accurate 3D model.

Archicad and Revit are the most popular softwares used for BIM modeling.

This model can be used for:

1. For spatial visualization of the building

2. For doing constructiblity analysis
eg if the slab level shown in architecural drawings and structural drawings are different or if a pipe if going through a lift shaft, then BIM would be able to identify that.

3. For generating sections from anywhere in the building. Time is saved as the BIM software does this automatically.

4. Preparing Bill of Quantities from the BIM model is fast. Take-off sheets can also be prepared. This is infact called the 4D or the cost.

5. The items in the Bill of Quantities can be exported to a scheduling software such as Primavera, MS Project or Vico Control to sequence the construction activities. The tasks have location data and quantity data already built into them, so scheduling is faster and more accurate. This is called 5D.

6. Future add-ons to BIM sofware would include structural analysis, energy analysis for calculating tonnage of air-conditioning required, preparing BBS for pre-fabrication, etc.

I have used BIM softwares on a few project and feel that a big change is underway in the construction industry.