Chapter 7Provisions for Structural Safety

7.1 Structural design and safety.- For any building under the jurisdiction of these byelaws structural/retrofitting design shall only be carried out by a registered Structural Engineer on Record (SER). Proof checking of various designs/ reports shall be carried out by competent authority as per Table 7.1wherever applicable.

7.1.1 Additional Provisions for natural hazard prone areas.- Generally, 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 –

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 of National Building Code of India (NBC), taking into consideration the Indian Standards as given below.

(1) IS: 456:2000 ‘Code of Practice for Plain and Reinforced Concrete’;

(2) IS: 800-2007 ‘Code of Practice for General Construction in Steel’;

(3) IS: 801-1975 ‘Code of Practice for Use of Cold Formal Light Gauge Steel Structural Members in General Building Construction’;

(4) IS 875 (Part 2):1987 Design loads (other than earthquake) for buildings and structures Part2 Imposed Loads;

(5) IS 875 (Part 3):1987 Design loads (other than earthquake) for buildings and structures Part 3 Wind Loads;

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

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

8. IS: 883:1994 ‘Code of Practice for Design of Structural Timber in Building;

9. IS: 1904:1986 (R 2005) ‘Code of Practice for Structural Safety of Buildings: Foundation’;

10. IS 1905:1987 ‘Code of Practice for Structural Safety of Buildings: Masonry Walls; and

11. 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

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

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

(14) IS: 1893 (Part 1)-2002 ‘Criteria for Earthquake Resistant Design of Structures (Fifth Revision)’

15. IS: 13920-1993 ‘Ductile Detailing of reinforced Concrete structures subjected to Seismic Forces-Code of Practice

(16) IS: 4326-2013 ‘Earthquake Resistant Design and construction of buildings code of practice (second revision)’

(17) IS: 13828-1993 ‘Improving earthquake resistance of low strength masonry buildingsguidelines

(18) IS: 13827:1993 ‘Improving Earthquake Resistance of Earthen Buildings-Guidelines

(19) IS: 13935-2009 ‘Seismic Evaluation, Repair and Seismic Strengthening of Buildings - Guidelines’

(20) IS 14458 (Part 1): 1998 Guidelines for retaining wall for hill area: Part1Selection of type of wall.

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

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

(23) IS 14496 (Part 2): 1998 Guidelines for preparation of landslide – Hazard zonation maps in mountainous terrains: Part 2 Macro-zonation.

Note: Whenever an Indian Standard including those referred in the National Building Code 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.

7.1.2 Structural Design Basis Report (SDBR).- In compliance of the design with the above Indian Standard, the Structural Engineer on Record will submit a structural design basis report in the Performa attached herewith covering the essential safety requirements specified in the Standard.

The ‘Structural Design Basis Report (SDBR)’consists of four parts

Part 1: General Information/ Data

Part 2: Load Bearing Masonry Buildings

Part 3: Reinforced Concrete Buildings

Part 4: Steel Buildings

(a) 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.

(b) 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

7.1.3 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 the SER. If as per the evaluation of the SER 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:

(1). For masonry buildings reference shall be made to IS 4326 and IS 13935

(2). For concrete buildings and structures reference shall be made to IS15988: 2013 Seismic

evaluation and strengthening of existing RCC buildings.

7.1.4 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 infill’s 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:

(a). 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,

(b). 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.

(1) The Authority shall create a Structural Design Review Panel (SDRP) consisting of senior SERs whose task will be to review and certify the design prepared by SER whenever referred by the competent authority.

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

(3) Table-7.1 gives requirements of SDRP for different seismic zones namely III, IV and V and for structures of different complexities.

(4) In seismic Zone II, buildings and structures greater than 40m in height will require proof checking by SDRP as per detail at Sl. no.3 of Table 7.1

1. Table 5.3may be referred for occupant load/live loads for different building types.

2.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 Client, the detailed calculations are performed on the selected scheme to determine the precise structural members and composition (size, dimension and stress behaviour), 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.

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

It will be seen from the Table 7.1 above that there is a wide range of structure typology, and the requirement by the Competent Authority for third party verification will depend on the type of structure.

4. SER may adopt suitable structural design software for designing the buildings.

7.1.6 Certification regarding structural safety in design.- Structural Engineer on Record (SER) shall give a certificate of structural safety of design as per Form-XV at the time of completion, stating that the structure of the building has been designed as per the relevant standards satisfying the soil investigation report submitted by GER and for the loads expected on the building and that the building will be structurally safe if constructed accordingly. (as per Clause 3.17)

7.1.7.1 Supervision.- All construction except load bearing buildings up to 3 storeys shall be carried out under supervision of the Construction Engineer on Record (CER) or Construction Management Agency on Record (CMAR) for various seismic zones.

7.1.7.2 Certification of structural safety in construction.- CMR shall give a certificate of structural safety of construction as per Performa given in Form- XVA at the time of completion, stating that the building is structurally safe and the construction is in accordance with the specified designs and drawings provided by SER (as per Clause 3.17).

7.1.8Quality control and inspection.- All material and workmanship shall be of good quality conforming generally to accepted standards of Public Works Department and Indian standard specification and codes as included in Part-V Building Materials and Part-VII Construction management, practices and safety of National Building Code of India.

7.1.8.1 Inspection.- All the construction for high-rise buildings higher than seven storeys, public buildings and special structures shall be carried out under quality inspection program prepared and implemented under the Building Quality Auditor (BQA) in seismic zones IV and V (as notified by the Government).

7.1.8.2 Certification of quality of construction.- Empanelled Quality Auditor on Record (QAR) shall give a certificate of quality control as per Performa given in Form- XVI

Quality Inspection Program to be carried on the site shall be worked out by BQA in consultation with the owner, builder and CMR.

Note: Clause 7.1.7 and 7.1.8 shall not be applicable for Government buildings that are designed and constructed under the supervision of in-house architects/engineers.

7.1.9Control of signage and outdoor display structures, cell phone towers and telephone Towers.- Following provisions shall apply for telecommunication infrastructure

(a) Location: The Telecommunication Infrastructure shall be either placed on the building roof tops or on the ground or open space within the premises subject to other regulations;

(b) Type of structure;

(i). Steel fabricated tower or antennae on M.S. pole;

(ii). Pre-fabricated shelters of fibre glass or P.V.C. on the building roof top /terrace for equipment;

(iii). Masonry Structure/ Shelter on the ground for equipment; and

(iv). D.G. set with sound proof cover to reduce the noise level.

(c) Requirement:

(i). Every applicant has to obtain/ procure the necessary permission from the ‘Standing Advisory Committee on Radio Frequency Allocation’ (SACFA)issued by Ministry of Telecommunications;

(ii).Every applicant will have to produce the structural safety and stability certificate for the tower as well as the building from the Structural Engineer on Record (SER) which shall be the liability of both owner and SER.; and

(iii). Applicant has to produce / submit plans of structure to be erected

(d). Projection: No Pager and/or Telephone Tower shall project beyond the existing building line of the building on which it is erected in any direction.

7.2 Inspection.- The general requirement for inspection and certification of the development shall be as prescribed in Clause no.3.10.6

7.2.1 Maintenance of Buildings.- In case of building older than fifty years, it shall be the duty of the owner of a building, to get his building inspected by a Structural Engineer on Record (SER) within a year from the date of coming into force of these regulations. The Structural Inspection Report (Form No.16, of the MHA Expert Committee Report) shall be produced by the Owner to the Appropriate Authority. If any action, for ensuring the structural safety and stability of the building is to be taken, as recommended by SER, it shall be completed within five years. For other buildings, the owner shall get his building inspected after the age of building has crossed forty years. The procedure shall be followed as per above regulation.

7.2.2Protective Measures in Natural Hazard Prone areas.- In natural hazard, prone areas identified under the land use Zonal 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.

7.3 Registration.- Registration of the required Professionals on Record (for drawings and supervision) has to be done as per the provisions of Appendix I and Appendix IA

7.4 Appointment of Professionals on Record.- The owner/promoter shall appoint the required Professionals on Record (for drawings and supervision) as per Appendix IA for the building licence and construction of the respective building.

7.5 Alternative Materials, Methods of Design and Construction and Tests.- The provision of the Bye-Laws is not intended to prevent the use of any material or method of design or construction not specifically prescribed by the bye-law provided any such alternative has been approved. The building materials approved by B.I.S. or any statutory body will form part of the approved building material and technology as part of the Bye-Laws.

The Authority shall promote and encourage use of Pre-fabricated factory-made building components for medium to large scale projects that have significant impact. The use of ready mix concrete (RMC) shall also be encouraged for in-situ concrete constructions.

Clause 11.2.6 may be referred for further aspects of Sustainability and incentivized promotion of alternative materials, methods in construction.