STRUCTURAL SAFETY



CHAPTER – V (G.O.119 Contd..)

PROVISIONS FOR STRUCTURAL SAFETY OF BUILDINGS

Structural Design and Safety

For any building under the jurisdiction of these Rules structural design/retrofitting shall only be carried out by qualified Structural Engineer.

Proof checking of various designs/reports shall be carried out by the Sanctioning Authority or an Agency authorized by the Sanctioning Authority as per  Table - 12 wherever applicable.

The Sanctioning Authority may consider to grant exemption for submission of working drawing, structural drawing and soil investigation report in case

The height of the building is less than 10m (excluding Stilt floor).

It is satisfied that in the area where the proposed construction is to be taken, similar types of structure and soil investigation reports are already available on record.

If the local site conditions do not require any soil testing or if a soil testing indicates that no special structural design is required.

Structural Design Basis Report (Form No. 6) has to be submitted, duly filled in case of a small building of load bearing structure up to Ground + 2 floors.

Additional provisions for natural hazard prone areas:

The structural design of foundations, elements of masonry, timber, plain concrete, reinforced concrete, pre-stressed concrete and structural steel shall conform to the provisions of Part 6:Structural Design of National Building Code of India (NBC), comprising –

  • Section–1 Loads, Forces and Effects
  • Section–2 Soils and Foundations
  • Section–3 Timber and Bamboo
  • Section–4 Masonry
  • Section–5 Concrete
  • Section–6 Steel
  • Section–7 Prefabrication Systems, Building and Mixed/Composite Construction

The same shall be followed duly taking into consideration the Indian Standards as given below:

For General Structural Safety

IS: 456:2000 “Code of Practice for Plain and Reinforced Concrete".

IS: 800-2007 “Code of Practice for General Construction in Steel".

IS: 801-1975 “Code of Practice for Use of Cold Formal Light Gauge Steel Structural Members in General Building Construction".

IS: 875 (Part 2):1987 “Design loads (other than earthquake) for buildings and structures Part 2 Imposed Loads". [Occupant Load a building may be considered for Design Load].

IS: 875 (Part 3):1987 “Design loads (other than earthquake) for buildings and structures - Part 3 Wind Loads".

IS: 875 (Part 4):1987 “Design loads (other than earthquake) for buildings and structures- Part 4 Snow Loads".

IS: 875 (Part 5):1987 “Design loads (other than earthquake) for buildings and structures - Part 5 special loads and load combination".

IS: 883:1994 “Code of Practice for Design of Structural Timber in Building".

IS: 1904:1986 (R 2005) “Code of Practice for Structural Safety of Buildings: Foundation".

IS: 1905:1987 “Code of Practice for Structural Safety of Buildings: Masonry Walls".

IS: 2911(Part 1): Section 1: 2010 “Code of Practice for Design and Construction of Pile Foundation Section 1".

  • Part 1: Section 2 Bored Cast-in-situ Piles
  • Part 1: Section 3 Driven Precast Concrete Piles
  • Part 1: Section 4 Bored Precast Concrete Piles
  • Part 2: Timber Piles
  • Part 3: Under Reamed Piles
  • Part 4:  Load Test on Piles

For Cyclone/Wind Storm Protection

IS: 875 (3):1987 "Code of Practice for Design Loads (other than Earthquake) for Buildings and Structures, Part 3, Wind Loads".

Guidelines (Based on IS 875 (3)-1987) for improving the Cyclonic Resistance of Low rise houses and other building.

For Earthquake Protection

IS: 1893 (Part 1)-2002 "Criteria for Earthquake Resistant Design of Structures (Fifth Revision)".

IS:13920-1993 "Ductile Detailing of Reinforced Concrete Structures subjected to Seismic Forces - Code of Practice".

IS:4326-2013 "Earthquake Resistant Design and Construction of Buildings - Code of Practice (Second Revision)".

IS:13828-1993 "Improving Earthquake Resistance of Low Strength Masonry Buildings - Guidelines".

IS:13827:1993 "Improving Earthquake Resistance of Earthen Buildings- Guidelines".

IS:13935-2009 "Seismic Evaluation, Repair and Seismic Strengthening of Buildings - Guidelines”.

For Protection of Landslide Hazard

IS: 14458 (Part 1): 1998 “Guidelines for retaining wall for hill area: Part 1 Selection of type of wall”.

IS: 14458 (Part 2): 1997 “Guidelines for retaining wall for hill area: Part 2 Design of retaining/breast walls”.

IS: 14458 (Part 3): 1998 “Guidelines for retaining wall for hill area: Part 3 Construction of dry stone walls”.

IS: 14496 (Part 2): 1998 “Guidelines for preparation of landslide – Hazard zonation

maps in mountainous terrains: Part 2 Macro-zonation”.

Note: Where an Indian Standard or the National Building Code is referred, the latest revision of the same shall be followed except specific criteria, if any, mentioned above against that code.

Buildings with Soft Storey

In case buildings with a flexible storeys, such as the ground storey consisting of open spaces for parking that is “Stilt buildings” or any other storey with open halls, special arrangements are to be made to increase the lateral strength and stiffness of the soft/open storey such as Steel bracing/Shear walls/Brick infills between columns.

Dynamic analysis of building is to be carried out including the strength and stiffness effects of infills and inelastic deformations in the members, particularly, those in the soft storey, and the structural members are to be designed accordingly.

Alternatively, the following design criteria are to be adopted after carrying out the earthquake analysis, neglecting the effect of infill walls in other storeys:

The columns and beams of the soft storey shall be designed for 2.5 times the storey shears and moments, calculated under seismic loads specified in the other relevant clauses; or,

Besides the columns designed and detailed for the calculated storey shears and moments, shear walls shall be placed symmetrically in both directions of the building as far away from the centre of the building as feasible; to be designed exclusively for 1.5 times the lateral storey shear force calculated as before.

For details of design and provisions, IS 1893, Part 1 shall be referred.

Structural requirements of low income housing

Notwithstanding anything contained herein, for the structural safety and services for development of low income housing the relevant provisions of applicable IS: 8888 Part 1 shall be enforced along with Annex C of Part 3 NBC, 2005.

Seismic strengthening/retrofitting

Prior to seismic strengthening/retrofitting of any existing structure, evaluation of the existing structure as regards structural vulnerability in the specified wind/seismic hazard zone shall be carried out by a Structural Engineer. If as per the evaluation of the Structural Engineer the seismic resistance is assessed to be less than the specified minimum seismic resistance as given in the note below, action will be initiated to carry out the upgrading of the seismic resistance of the building as per applicable standard guidelines.

Note:

  • For masonry buildings reference shall be made to IS 4326 and IS 13935.
  • For concrete buildings and structures reference shall be made to IS15988: 2013 Seismic evaluation and strengthening of existing RCC buildings.

Structural Design Basis Report (SDBR)

In compliance of the design with the above Indian Standard, the Structural Engineer will submit a structural design basis report in the Proforma covering the essential safety requirements specified in the Standard.

The “Structural Design Basis Report (SDBR)”consists of four parts (FormNo.6, MHA Expert Committee Report)

  • Part 1: General Information/ Data
  • Part 2: Load Bearing Masonry Buildings
  • Part 3: Reinforced Concrete Buildings
  • Part 4: Steel Buildings

Drawings and Documents to be submitted for approval of appropriate authorities shall include SDBR as detailed below:

  • Part 1: Completed
  • Part 2: (if applicable) – completed
  • Part 3: (if applicable)–undertaking that completed Part 3 will be submitted before commencement of construction.
  • Part 4: (if applicable)–undertaking that completed Part 4 will be submitted before commencement of construction.

SDBR as detailed below shall be submitted to the appropriate authority as soon as design of foundation is completed, but not later than one month prior to commencement of construction.

  • Part 1: Completed
  • Part-2, Part-3 or Part-4: (if applicable) Completed.

 Review of Structural Design

 The Authority shall create a Structural Design Review Panel (SDRP) consisting of Reputed Engineering Colleges whose task will be to review and certify the design prepared whenever referred by the Authority.

 The Reviewing Agency shall submit addendum to the certificate or a new certificate in case of subsequent changes in structural design.

 The Table below gives requirements of SDRP for different seismic zones namely III, IV and V and for structures of different complexities.

 In seismic Zone II, buildings & structures greater than 40m in height will require proof checking by SDRP as per detail at Sl. No.3 of the Table given below.

 It will be seen from the Table given below that there is a wide range of structure typology, and the requirement by the Authority for third party verification will depend on the type of structure.

Sl.No Type of Structure Submission form SER or SDAR To be Proof Checked
A B C D
1

Load  Bearing  Buildings up to 10m height

Structural Design Basis Report (SDBR) Not to be checked
2

Buildings  up to 18m height (including Stilt floor) (R.C.C/Steel framed structure)

SDBR To be checked
Preliminary design To be checked
3

Building greater  than 18m height (including Stilt floor)(R.C.C/Steel framed structure)

SDBR To be checked
Preliminary design To be checked
Detailed structural design and structural drawings To be checked
4 Special Structures SDBR To be checked
Preliminary design To be checked
Detailed structural design and structural drawings To be checked

Notes:                                 

At the preliminary proposal stage of a project, the objective is to undertake feasibility study/comparison of a number of possible alternatives of structural schemes and determine the most cost effective one, detailed structural calculations are not necessary for each alternative scheme. However, it is necessary to determine the member sizes and reinforcement content in order to determine the cost. By making conservative assumptions it is possible to derive simplified calculations for both analysis and design. This is called “Preliminary or approximate analysis, and design”.

After the most cost effective scheme is selected and signed-off by the Owner, the detailed calculations are performed on the selected scheme to determine the precise structural members and composition (size, dimension and stress behavior), and this is called the “Detailed structural design”.

In the aforesaid, the design of structural members is typically assumed to account for all the stress loads identified from section xx to be applicable in the given project.

Special structure means large span structures such as stadium, assembly halls, or tall structures such as water tanks, TV tower, chimney, etc.

Certification regarding structural safety in design and constructional safety

Structural Engineer shall give a certificate of structural safety of design as per proforma given in Form-3 and Form 14 of the MHA Expert Committee Report at the time of completion.

Supervision

All constructions except load bearing buildings up to three storeys shall be carried out under the supervision of the Structural Engineer for various seismic zones.

 Certification of structural safety in construction

The Structural Engineer shall give a certificate of structural safety of construction as per proforma given in Form-13 of the MHA Expert Committee Report at the time of completion.

Quality Control, Construction Practices and Safety

All material and workmanship shall be of good quality conforming generally to accepted standards and Indian Standard Specifications and Codes as included in Part-V Building Materials and Part-VII Construction practices and safety of National Building Code of India.

Inspection

All the constructions for high-rise buildings, public buildings and special structures shall be carried out under quality inspection program prepared and implemented under the Quality Auditor in seismic zones IV & V.

Certification of safety in quality of construction

Quality Auditor shall give a certificate of quality control as per proforma given in the prescribed Form.

Inspection

The general requirement for inspection of the development shall also include the following.

General Requirements

The building unit intended to be developed shall be in conformity with Rules on requirement of site. Generally all development work for which permission is required shall be subject to inspection by the Authority as deemed fit.

The applicant shall keep a board at site of development mentioning the survey No, city survey No, Block No, Final Plot No., Sub plot No., etc. name of owner and name of Architect, Engineer, Developer, Structural Engineer, Construction Engineer if any and also the details of the approval given by the Authority.

Record of Construction Progress

Stages for recording progress certificate and checking:-

Plinth, in case of basement before the casting of basement slab.

First storey.

Middle storey in case of High-rise building.

Last storey.

At each of the above stages, the Owner/Developer/Builder shall submit to the designated officer of the Sanctioning Authority a progress certificate in the given formats (Form No. 7-10, of the MHA Expert Committee Report). This progress certificate shall be signed by the Structural Engineer.

The progress certificate shall not be necessary in the following cases:

Alteration in Building not involving the structural part of the building.

Extension of existing residential building on the ground floor up to maximum 15sq.m in area.

Completion Report

It shall be incumbent on every applicant whose plans have been approved, to submit a completion report in Form No.11 of the MHA Expert Committee Report.

It shall also be incumbent on every person / agency who is engaged under the Rules to supervise the erection or re- erection of the building, to submit the completion report in Form No.12 and 13 of the MHA Expert Committee Report prescribed under these Rules.

No completion report shall be accepted unless completion plan is approved by the Authority.

The final inspection of the work shall be made by the concerned Authority within 15 [Fifteen] days from the date of receipt of notice of completion report.

The developers shall install CCTVs at construction sites of all Commercial Buildings, Group Development Schemes and High-Rise Buildings connecting to A.P State Fibernet Limited Network to analyze the information.

Issue of Occupancy Certificate

The Authority, before issuing occupancy certificate shall ensure that following are complied with from consideration of safety against natural hazard:

Certificate of lift Inspector has been procured & submitted by the owner, regarding satisfactory erection of Lift.

The Certificate from the Disaster Response and Fire Services Department with regard to the provision of fire safety as required under the Andhra Pradesh Fire Service Act, 1999 has been complied with and submitted by the owner.

The occupancy certificate shall not be issued unless the information is supplied by the Owner and the Architect, Structural Engineer concerned in the schedule as prescribed by the Sanctioning Authority from time to time.

For obtaining the Occupancy Certificate, the owner shall submit a notice of completion through the registered architect and licensed builder/developer along with prescribed documents and plans and Final NOC from the Andhra Pradesh Disasters Response and Fire Services Department to the Building Approving Authority. The Building Approving Authority on receipt of such notice of completion shall undertake inspection with regard to the following aspects and shall communicate the approval or refusal of the occupancy Certificate within 15 days.

  • Number of floors
  • External setbacks
  • Parking space provision
  • Abutting road width
  • Rain Water Harvesting Structures, as applicable.
  • Solar roof top structures, as applicable.
  • Recycle of water treatment plants, as applicable.

Protective Measures in Natural Hazard Prone areas [Wherever applicable]

In natural hazard prone areas identified under the land use zoning regulations, structures buildings and installations which cannot be avoided, protective measures for such construction/development should be properly safeguarded based on the suggestion given in the Report of the MHA Expert Committee - Volume I.

Alternative Materials, Methods of Design and Construction and Tests

The provisions of the Rules are not intended to prevent the use of any material or method of design or construction not specifically prescribed in them provided any such alternative has been approved.

The Authority may approve any such alternative, provided it is found that the proposed alternative is satisfactory and conforms to the provisions of the relevant parts regarding materials, design and construction, method of work offered for the purpose intended, at least

equivalent that prescribed in the rules in quality, strength, compatibility, effectiveness, fire, water and sound resistance, durability and safety.

Tests: Whenever there is insufficient evidence of compliance with the provisions of these rules or evidence that any material or method of design or construction does not conform to the requirement of the rules, in order to substantiate claims for alternative materials, design or methods of construction, the Authority may require tests sufficiently in advance as proof of compliance. These tests shall be made by approved agency at the expense of the owner. This clause shall not apply to the materials with BIS Certificate.

Test Methods shall be as per the relevant IS Codes.

Test Result Copies shall be retained by the Authority for a period of not less than two years after the acceptance of the alternative materials. The testing of materials as per the Indian Standards shall be carried out by the laboratories approved by the concerned Authority on this behalf.

Maintenance of Buildings

In case of buildings older than fifty years, it shall be the duty of the owner of a building, to get his building inspected by a Registered Structural Engineer within a year from the date of coming into force of these Rules or as decided by the Authority. The Structural Inspection Report Form No.16, of the MHA Expert Committee Report shall be produced by the Owner to the Concerned Authority. If any action, for ensuring the structural safety and stability of the building is to be taken, as recommended by Structural Engineer, it shall be completed within the time period as stipulated by the Authority.

The Owner/developer/occupant on the advice of such experts shall carry out such repair/restoration and strengthening/retrofitting of the building found necessary so as to comply with the safety standards.

In case, the owner/developer/occupant does not carry out such action, the Authority or any agency authorized by the Authority may carry out such action at the cost of the owner/developer/occupant.

Building Services

Electrical Installations

The Planning, design and installation of electrical installation, air-conditioning and heating work shall conform to the provisions of Part VIII Building Services; Section 2 – Electrical Installations; Section – 3 Air-conditioning and Heating of NBC.

Plumbing Service

The Planning, design and installation of water supply systems, drainage, sanitary installations and gas supply installations in buildings shall be in accordance with Part XI Plumbing Services; Section 1-Water supply; Section 2- Drainage and Sanitation and Section 3 – Gas supply of NBC.

Lifts

The Planning, design and installation of lifts including their number, type and capacity depending on the occupancy of the building, the population on each floor based on the occupant load of the building, height shall be in accordance with Section 5 – Installation of Lifts and Escalators of NBC.

Maintenance: The lift installation should receive regular cleaning, lubrication, adjustment and adequate servicing by authorized competent persons at such intervals as the type of equipment and frequency of service demand. In order that the lift installation is maintained at all times in a safe condition, proper maintenance schedule shall be drawn up in consultation with the lift manufacturer and rigidly followed. A log book to record all items relating to general servicing and inspection shall be maintained, the electrical circuit diagram of the lift with the sequence of operation of different components and parts shall be kept readily available for reference by persons responsible for the maintenance and replacement, where necessary to the satisfaction of the Authority.

Any accident arising out of operation and maintenance of the lifts shall be duly reported to the Authority.

Note:   Ministry of Home Affairs [ MHA] Expert Committee Report on Structural Safety, 2005 is available at the National Disaster Management Authority [ NDMA] website.

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