Systems consisting of linear members Disunited at joints

Systems consisting of linear members Disunited at joints:

Disuniting act joints gives linear members

The disadvantage of this system is that the joints are at the corners, i.e at places where the moments usually reach their maximal values, so the forming of the joints is difficult.

The quality of subsequent concreting executed in site is only exceptionally and at readily accessible places as good as the concrete quality of precast members. Therefore the joints must be over dimensioned.

System for the prefabrication of Entire Rigid Frame:-

The trend to numbers of joints to precast larger members in one piece lands to the prefabrication of entire frames.

Properly carried out in the horizontal position only.

The prefabrication of larger arches in the horizontal position is found to be more economical using this method the arches must be tilted up and this involves the solution of an additional problem.

The construction of arched trusses can be properly carried out in the horizontal position only.

Prefabrication:-

Pre fabricated building is completely assembled and erected building of which the structural parts consist of pre fabricated individual units on assemblies.

Pre fabricated construction is a new technique and is desirable for the scale houring programmes.

Principles: (Aims)

1.     To effect economy in cost.

2.     To import in quality as the components can be manufactured under controlled conditions.

3.     To speed up construction since no curing period is necessary.

4.     To use locally available materials with required characteristics.

5.     To use the materials which possesses their innate characteristics like light-weight easy workability.

v    Materials for scaffolding is stored partly & in full and used.

v    Availability of precise structure and expect workmanship.

v    Work time is reduced

v    Fewer expansion points are required.

v    Interruption in connection can be omitted.

v    Work is done with a better technology.

v    Less workers are needed

v    Members can be used again.

Materials used:-

The materials used a prefabricated components are many. The modern trend is to use concrete steel treated wood aluminum cellular concrete, light weight concrete ceramic products etc.

Which choosing the materials for pre fabrication the following special characteristics are to be considered and transported and to economic an sections and sizes of foundations.

v Thermal insulation property.

v Easy workability

v Durability in all weather conditions.

v Non-Combustibility

v Economy in cost

v Sound insulation.

Modular Co-ordination :-

Only basic modules to be adopted. Basic module is the fundamental module used in modular co-ordination. The size of basic module's selected for general applications for

building and its components. The value of basic module chosening 100mm for maximum flexibility and convenience. The symbol used for basis module is M. After adopting this, further work is necessary to outline suitable range of multi module with greater increments, often referred to as preferred increments are adequate for meeting the requirements of conventional ad prefabricated construction. These rules relate to the following basic elements.

Modular co-ordination :-

1) The planning grid in both directions of the horizontal plan shall be:

a.     3m for residential and institutional buildings.

b.     For industrial buildings : 15 M for spans up to 12 M.

30 M for spans between 12 M and 18 M and 60 M for spans over 18 M. The Centre lines of load bearing walls shall concede with the grid lines.

2)                In case of external walls, the grid lines shall coincide with the centre line of the wall

of a line on the wall direction shall be 1M up to ad including a height of 2.8 m; above the height of 2.8 M it shall be 2M.

3)

4.                 Preferred increments for rill lights doors, windows etc. shall be 1 M.

5.                 In the case of internal columns the gridlines coincide with the centre lines of columns. In case of external columns ad columns near the lift and stairwells the grid lines shall coincide with centre lines of the column in the top most storey or a line in the column 50mm from the internal face of the column in the top most storey.

Advantages of standardization :-

The following are the advantages of standardization.

1)    Easier in design as it eliminates unnecessary choices.

2)    Easier in manufacture as there are limited number of variants.

3)    makes repeated use of specialized equipments in erection ad completion easier ad quicker.