Nespak Earthquake Reconstruction and Rehabilitation Project

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the specifications followed for Building Earthquake safe structures and Alternative Technologies

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Any structure in which no consideration is given to seismic parameters is known as ordinary structure. Structures designed for gravity loads, in general, may not be able to safely sustain the effects of horizontal earthquake shaking. Hence, it is necessary to ensure adequacy of the structures against horizontal earthquake effects.

Short Comings in previously constructed Buildings
	Improper Lateral Bracings
	Less Reinforcement
	Poor Beam Column Joints
	“Picked-up column” having no connection with rest of the building
	Insufficient column ties (rings)

Seismic Zone	Peak Horizontal Ground Acceleration
1	0.05 to 0.08g
2A	0.08 to 0.16g
2B	0.16 to 0.24g
3	0.24 to 0.32g
4	>0.32g

Where "g" is the acceleration due to gravity

SITE CONSIDERATIONS
	Select proper location to get sample for Bearing Capacity of soil
	Placement of foundation up to required depth as mentioned in drawings
	Read structural drawings in conjunction with architectural, plumbing and electrical drawings
	Make proper hooks as per drawings and rotate them clockwise or anti clock wise in beams and columns (Ties). Shape of Hook(180',135',90')
	Tie main bars and rings properly
	Maintain cover in all components of the structure. Spacer, Chair, etc
	Splice (Position, Length, Hook of each part)
	Anchorage (Dowel)

General Seismic Considerations
	The principal goal of the Special Provisions is to ensure adequate toughness under inelastic displacement reversals brought on by earthquake loading.
	The provisions accomplish this goal by requiring the designer to provide for concrete confinement and inelastic rotation capacity.
	No special requirements are placed on structures subjected to low or no seismic risk.
	Structural systems designed for high and moderate seismic risk are referred to as "Special" and "Intermediate" respectively.

provisions - hoops, ties & crossties
	Confinement for concrete is provided by transverse reinforcement consisting of stirrups. Hoops and crossties.
	To ensure adequate anchorage, a seismic hook [with a bend not less than 135° and a 6 bar diameter (but not less than 3 in.) extension that engages the longitudinal reinforcement and projects into the interior of the stirrup or hoop] is used on stirrups, hoops and crossties.
	Hoops are closed ties that can be made up of several reinforcing elements, each having seismic hooks at both ends, or continuously wound ties with seismic hooks at both ends.
	A crosstie is a continuous reinforcing bar with a seismic hook at one end and a hook with not less than a 90° bend and at least a 6 bar diameter extension at the other end. The hooks on crossties must engage peripheral longitudinal reinforcing bars.

Provisions for beams
Size	Beam width must not be less 10 inches
Flexural Reinforcement	Min two reinforcing bars top and bottom, throughout the member.
Lap splices	Not within the joints and preferable to provide at mid span of the member.
Transverse reinforcement (Stirrups)	First stirrup has to be placed after 2” from face of the column, and is provided at half space within the length upto two times depth of beam.

Provision for Columns
Size	Each side at least 12”& Shorter to longer side ratio ≥ 0.4.i.e. 12/12, 12/18, 12/24 OK; but 12/36 not O.K
Flexural Reinforcement	0.01< rg<0.06 or min four (04) bars must be provided.
Lap splices	Must be provided within the middle half as shown Tie spacing at lap splice is d/4 or 4 inch, whichever is less. Where “d” is effective depth along least dimension of column.