Prestressed concrete members should be compacted by mechanical vibrations expect when certain types of extrusion machines are used which consolidate concrete by tamping and depending on type of structural members, internal, external or surface type vibrators are used and normally vibrators having frequencies in range of at least 3200-3600 cycles per minute are used.

The hanger provides a clear uninterrupted space of 91.4m long with an average height of 13m so that two airbus aircrafts can easily be parked in hanger and also an expansion joint planned and provided at centre divides roof into two units of 45.7m each.

In case of large floor and roof coverings using prestressed concrete as material, re are several types of structural forms for adoption and some of m are as follows: Tee beam and slab floors, continuous beam and slab floors, coffered or grid floors, flat slab floors, folded plate roofs, shell roofs, spherical domes, trusses and framed roofs, composite construction using prestressed and reinforced concrete.

Degussa-MBT construction chemicals (INDIA) have developed revolutionary type of admixtures using nano polymers which can be used to bring toger functional groups aimed at targeted performances in concrete and based on nano science.

For heavily reinforced concrete members as in case of ribs of main beams, nominal maximum size of aggregate shall be 5mm less than spacing between cables, strands or sheathings and aggregates containing particular varieties of silica, which are suspectable to attack by alkalis present in cement resulting in expansive reaction should be avoided.

The nuclear containment structure of an atomic reactor is a physical barrier which is designed to contain total fluid energy and radioactive products in event of which is termed as maximum credible accident (MCA) and MCA corresponds to rupture of pipes carrying primary or secondary coolants and associated rise of pressure and temperature within containment structures.

The structure comprises prestressed concrete folded plates cantilevering on opposite sides from main service complex and long cantilever span can be considered as world record for this type of construction which was chosen to achieve flexibility of lateral expansion without distributing existing facilities.

The capacity of such tanks may vary from 400 to nearly 40000m³ and economical dimensional proportions for water tanks as reported by preload engineering company, Newyork and ses tanks are provided with reinforced concrete domes having a thickness ranging from 50-110mm with a prestressed concrete ring beam at junction of cylindrical tank walls and spherical dome.

The thickness of concrete in shell is in range of 50-75mm and curved shell segments are connected by cast insitu joints which are prestressed by suitable high tensile cables and transverse directions at modular intervals to achieve integrity of joints resulting in large interrupted space inside shell.

Practical engineers must be more conceptual than mere perceptual, more creative than mere analytical and more visual than mere mamatical and construction engineers should have wide experience involving several types of structures rar than isolated narrow specialization and expertise and original skill are attained from relentless understanding and practice rar than mere oretical knowledge and good and sound judgment are attained from wide practical experience and often experience comes from bad judgment.