Red Cedar Consultancy Services, Structural audit report provides information about distressed areas and RCC Structural damages, and also takes care for the seepages and dampness arising in the structures due to external and internal factors as well. These seepage are the core reason for causing failures in the structure.
2. Type Of Building Construction
A. Based On Construction Method
B. Based On Design & Supervision
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RED CEDAR
3. A. Based On Construction Method
Load Bearing Wall With Step/Strip Footing
R.C.C. Frame Work
Precast Structural Frame Work
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4. Redesigning existing structure for nature forces
It is a comprehensive task & require planning which
include following Information gathering.
Field investigations including details of sub strata,
foundation details, extent of damage
Type of Existing structure & its members stability
Design Data Collection
Identification of components required to be
strengthened
Cost Estimates (it is feasible up to 60% of new
construction)
Method or Procedure to be followed.
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6. Crack Location In Structure
Foundation:
1. Cracks Travel vertical in step footing in case of unequal
settlement.
Flooring:
1. It is circular, Linear.
Column:
1. Generally at 1/3rd height from bottom & top depending
on fixing conditions of column ends.
2. At laps location ,if laps are not staggered or not
sufficient length.
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7. Brick Work:
In wall at ends of lintel in Diagonal upward
directions.
1. Horizontal, generally at slab wall joint , when
whole wall sink.
2. Vertical, in case of unequal settlement
Beam:
1. Near Support ,visible on both face of beam &
bottom.
2. At centre of beam in its bottom
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8. Slab :
1. At centre of Span in ceiling (slab bottom)
2. At top & bottom face of slab near the
supporting wall or at top surface in case of
cantilever
Plaster:
1. At joints with R.C.C & brick work
2. At localized locations in wall due to different
reasons
3. Locations as briefed in cracks in B.W.
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9. Make structure floor, roof lighter as much as possible.
Avoid Un- symmetry of structure as much as possible.
For this purpose structure can be divided.
Sand Pilling ,Stabilization of weak soil, sandy soil
having high water level must be taken care off.
Proper Connections of building Elements.
Use steel to strengthen laterally for load bearing wall
as per code requirement.
Provide adequate plinth protection.
Avoid to built Rigid masonry Building freely resting on
rock in Earth Quack porn area.
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10. Avoid keeping shallow foundation on Black Cotton
Soil.
Use one type of foundation in a whole building to
avoid differential settlement.
Physical quality check on material should me
periodic.
An addition of room, which is structurally
independent from an existing building should be
designed & constructed in accordance with the
seismic requirements of new compiled structures.
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11. Any existing seismic resistance building if
occupied for school building then the building
has to be rechecked for seismic resistance for
building importance factor of 1.5.
Projecting parts like cornices, facia stones,
parapets etc. should be avoided as for as
possible, otherwise they should be properly
reinforced and firmly tied to the main structure
Refer IS 1893 CLAUSE -7.12.2
Ceiling plaster should be avoided as possible.
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12. Whenever one un symmetrical building is divided
into two or more building by separation walls the
structure of the divided building up to plinth level
is generally monolithic. Refer code IS 4326 5.1 to
5.2
Even Where calculations based on code- based
seismic coefficients may not indicate tension steel
requirements, the reinforcement suggested in the
form of seismic bands & vertical steel bars at
corners & junction of walls & jambs of openings
must be provided since these are safe guard for
probable maximum earthquake.
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13. Corrosion resistance precautions should also be
taken in ductility detailing of cyclone prone &
tsunami prone coastal areas.
IS 456 does not allow R.C.C. below M20 grade.
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14. An addition of new structure which is not structurally
independent should be designed & constructed such
that the entire building conforms to the seismic
resistance requirements for new building configuration.
The addition should not increase the seismic force
in any structural elements of the existing building by
more than 5% unless the capacity of the element
subject to the increased force is still in compliance
with the standard.
The addition should not decrease the seismic
resistance of any structural element of the existing
building below that required by the design codes.
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15. For more details
Red Cedar Consultancy services
At
www.auditstructures.in
Cell – 8879 33 55 31
Email: rajeshb08@gmail.com
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Editor's Notes
This presentation should be read in continuation of presentation 1 & 2 which were on low strength masonry building , building of higher strength of masonry & R.C.C.
Major task is to redesign an existing old structure for functional & earthquake, cyclone or more than one reasons without having any design & drawing of existing structures. Information are gathered & investigated by surveyor, architect ,designer, estimator to decide feasibility of retrofitting as per SSA norms.
Cracks investigations. we have already dealt in our earlier presentations & which are on SSA website .Those cracks which are stable & non increasing are easiest to repair.& those cracks which are expanding or changing in shape need further investigations for cause & then elimination of cause & then off course repair of cracks is carried out.
There are three slides which may help to identify some of major important cracks & its cause. For all cracks please refer earlier presentation of TSG in SSA web site.
Some time we may find crack at corner in joint of two load bearing wall & cracks also in floor. In such case we should also check verticality of walls. In my view When wall is out of plumb by more than 10mm in 3.0 m then it is better to re built the wall from foundation after foundation soil stabilization. If wall is vertical then two wall can be connected as per slides shown, latter on in this presentation.
I again repeat that I have already dealt on cracks in detail in my earlier presentations. Please refer those presentation . next
This is third slide on structural & non structural crack locations.
These are some of tips for school building planning, designing & executions.
Avoid keeping shallow foundation on Black Cotton Soil.
Use one type of foundation in a whole building to avoid differential settlement.
Physical quality check on material should me periodic.
An addition of room, which is structurally independent from an existing building should be designed & constructed in accordance with the seismic requirements of new compiled structures
Any existing seismic resistance building if occupied for school building then the building has to be rechecked for seismic resistance for building importance factor of 1.5.
Projecting parts like cornices, fascia stones, parapets etc. should be avoided as for as possible, otherwise they should be properly reinforced and firmly tied to the main structure Refer IS 1893 CLAUSE -7.12.2
Ceiling plaster should be avoided as possible
Whenever one un symmetrical building is divided into two or more building by separation walls the structure of the divided building up to plinth level is generally monolithic. Refer code IS 4326 5.1 to 5.2
Codes says that Even Where calculations based on code- based seismic coefficients may not indicate tension steel requirements, the reinforcement suggested in the form of seismic bands & vertical steel bars at corners & junction of walls & jambs of openings must be provided since these are safe guard for probable maximum earthquake.
Corrosion is reduced by proper selection of cement, aggregate, water & cover around bar. There are cement which are acid & alkaline resistant as per requirement. Aggregate should be chemically passive i.e. inert & Cover should be as per code IS 456 requirement.
This slide show designing information but we as a engineer should know that An addition of new structure which is not structurally independent should be designed & constructed such that the entire building conforms to the seismic resistance requirements for new building configuration.
The addition should not increase the seismic force in any structural elements of the existing building by more than 5% unless the capacity of the element subject to the increased force is still in compliance with the standard.
The addition should not decrease the seismic resistance of any structural element of the existing building below that required by the design codes.
This slide show designing information but we as a engineer should know that An addition of new structure which is not structurally independent should be designed & constructed such that the entire building conforms to the seismic resistance requirements for new building configuration.
The addition should not increase the seismic force in any structural elements of the existing building by more than 5% unless the capacity of the element subject to the increased force is still in compliance with the standard.
The addition should not decrease the seismic resistance of any structural element of the existing building below that required by the design codes.