NEPAL NATIONAL BUILDING CODE
NBC 111 : 1994

STEELGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC108V2.RV97 December 1993

NEPAL NATIONAL BUILDING CODE
NBC 111 : 1994

STEEL

This publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064
NBC108V2.RV97 December 1993

iPrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a National Building
Code for Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs ofNepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements
or good practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
this document has been prepared by the subcontractor's team working within the Department ofBuilding, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction ProjectPresident, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
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ii
Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA
Principal inputs to this standard came from :Mr. RD Jury, BECARevisions and Updated to this code came from :Mr. Purna P. Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. DIV. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex.DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt. Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, Mr Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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iii

TABLE OF CONTENTS

Preface ..................................................................................................................................................... i0Foreword.................................................................................................................................. iv

1Scope.......................................................................................................................................... 1
NEPAL AMENDMENTS TO IS 800 – 1984 .............................................................. 1
SECTION 0 ...................................................................................................................... 1
SECTION 1-GENERAL .................................................................................................... 1
SECTION 2 – MATERIALS .............................................................................................. 2
SECTION 3 – GENERAL DESIGN REQUIREMENTS ......................................................... 2
SECTION 10 .................................................................................................................... 4
SECTION 12 .................................................................................................................... 4
SECTION 13 -PROVISIONS FOR SEISMIC DESIGN .......................................................... 4

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iv0Foreword
This Nepal Standard comprises the Indian Code IS 800-1984 Code of practice for General
Construction in Steel (Second Revision) with amendments as set out herein. These amendments
have been necessary to ensure compatibility with the Nepal Standard- Seismic Design ofBuildings in Nepal.
References to Indian material codes have been left unaltered until such time as appropriate
Nepal Standards are developed.
Extensive use of the New Zealand Standard NZS 3404 : 1977 Code for Design of SteelStructures have been made in the preparation of Section 13.

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11Scope
NEPAL AMENDMENTS TO IS 800 – 1984
Section 0Delete clauses 0.1 through to 0.5 inclusively

Section 1 -General

1.1.1

Delete 1.1.1 and substitute :1.1.1This standard applies to general construction in steel. This standard does not
apply to the following structures and materials:
(a)
(b)
(c)
(d)
(e)
(f)

bridgescranestanks
transmission towers
materials less than 3 mm thickcold-formed light gauge sections

1.1.2

Replace "code" with "standard"

1.1.3

Replace "code" with "standard"
Replace IS 875-1964 with NBC 103-2050 and NBC 104-2050

1.1.4

Add new clause :1.1.4

In this standard the word "shall" indicates a requirement that must beadopted in order to comply with the Standard.

1.2

Replace "code" with "standard".

1.3

Replace "code" with "standard".

1.4

Replace IS 456-1976 with NBC 110-2050
Replace IS 1893-1975 with NBC 105-2050

1.5

Delete 1.5 and substitute :
1.5

1.7

Units and Conversion Factors – The SI system of units is applicable to thisstandard.

Delete 1.7 and substitute :1.7
Design and supervision
1.7.1 Design

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2
The design of a structure or part of a structure to which this standard isapplied shall be the responsibility of a engineer (referred herein as
Design Engineer or his representative) experienced in the design of suchstructures.
1.7.2

Supervisor
All stages of construction of a structure or part of a structure to which thestandard is applied shall be adequately supervised to ensure that allrequirements of the design are satisfied in the completed structure.
Supervision shall be the responsibility of either :(a)(b)

the Design Engineer, oran engineer experienced in such supervision.

Section 2 – Materials
2.1

Replace "code" with "standard"

2.1.2

Add new clause :2.1.2The maximum value of ƒy to be used in application of this Standard shallbe 450 MPa.

Section 3 – General Design Requirements
3.1.1.1

Replace "IS 875 – 1964" with NBC 103-2050 and NBC 104-2050.

3.1.1.4

Replace "IS 1893 – 1975" with NBC 105-2050 and NBC 104-2050.

3.2.1

8th line, replace "code" with "standard".

3.2.2

4th line, replace "India" with "Nepal".
[Will require preparation of maps for Nepal to replace those in Appendix A]

3.4.2.2

Delete 3.4.2.2 and substitute :
3.4.2.2

Wind loads and earthquake loads need not be assumed to act
simultaneously.

3.4.5

9th line, replace "code" with "standard".

3.4.6

9th line, replace "code" with "standard".

3.9.2.1

Delete and substitute :NBC111VO.RV2

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3
3.9.2.1

3.11

Wind and Earthquake Loads(a)Structural steel and steel castings – when the effect of wind or
earthquake load is taken in to account, the permissable stresses
specified may be increased by not more than 33.3 percent except
for the permissable shear stresses which shall not be exceeded bymore than 25 percent. The values of the expressions given inSection 7 shall not exceed 1.33.

(b)

Rivets and bolts – when the effect of wind or earthquake load istaken in to account, the permissible stresses specified may be
increased by not more than 25 percent.

Delete and substiute :3.11.1

Earthquake forces
The design of structures to resist earthquakes shall be in accordance with
the Nepal Standard – Seismic Design of Buildings in Nepal and Section
13 of this Standard.

3.11.2Lateral Restraint
In buildings where high-speed travelling cranes are supported by thestructure, or where a building or structure is otherwise subjected tovibration or sway, triangulated bracing, rigid portal systems or othersuitable systems shall be provided to reduce bivration or sway to suitable
minimum.

3.11.3

Foundations
The foundations of a building or other structure shall be designed toprovide the lateral rigidity and strength assumed in the design of thesuperstructure and to transfer the lateral forces to the soil.

3.12.1.2

Correct spelling of "repair".
Add a new clause :3.12.1.3

Eccentric Loading
Where a load is applied eccentrically on a flange of a supporting steel
beam, the beam and its connections shall be designed for torsion; unlessthe beam is encased in concrete and reinforced in combination with anadjoining floor slab in such a way as to present the beam from deforming
torsionally.

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4
3.13.2

Add an additional clause :3.12.2.3

Deflection Limits
Under the application of the earthquake design forces the deflections
shall not exceed the limits given in NBC 105-2050, Seismic Design of
Buildings in Nepal.

3.14

Add additional clause :3.14.4

Separate Structures
All parts of a structure separated by expansion joints shall be considered
as separate structures for the purposes of providing lateral restraint toresist earthquake frames.

Section 10

Add after the heading a sentence reading :This Section shall apply only to secondary (i.e. non seismic resisting) members.

Section 12

After Section 12 add a new section :Section 13 - Provisions for Seismic Design
13.1

Ductile Moment-Resisting Frames
13.1.1

GeneralMoment-resisting frames for which a value of K = 1.0 is to be used in theassessment of the earthquake design forces shall be detailed inaccordance with 13.1.

13.1.2

SteelsSteel with a specified minimum yield stress not exceeding 360 MPa shallbe used. Cold-formed sections which have not been normalised shall not
be used.

13.1.3

Plastic Hinge Formation in Beams
For the purposes of 13.1, plastic hinges in beams shall be assumed toform be used. Cold-formed sections which have not been normalised
shall not be used.

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513.1.4

Lateral Restraint
Positions of beams where plastic hings may form during inelastic
displacements of the frame, and all columns shall comply with 9.2.10.
The remaining portions of the beams shall comply with 6.6.
13.1.5 Effective Lengths of Columns and Stability
The effective length used in determining the slenderness ratio of a loaded
column shall be based on the assumption that the frame depends on its
own bending stiffness to provide the lateral stability of the structure, asspecified in 5.2.2, even if bracing or shear walls are provided elsewherein the structure.

13.1.6

Plastic Hinge Formation and Column Strength
Multi-storey frames should be designed so as to ensure that plastic hinge
formation in the columns is minimised. To this end, it is suggested that inframes over five storeys in height columns should be proportioned foractions calculated in accordance with the Nepal Standard – Seismic
Design of Buildings in Nepal, taking K = 1.25. This will provide somereserve in the columns but will not necessarily prevent some plastic
hinging in the columns.

13.1.7

Connections
Each beam connected to a column shall be designed either to resist 1.25
times the design actions in the connected members, or the actions
resulting from applications of design forces calculated using K = 4,
whichever is less. Clause 9.2.1 shall apply, except that stiffeners shallextend over the full depth between flanges and shall be butt-welded toboth flanges.

13.1.8Concrete Encasement of Steel Frames
The effects of concrete-encasement and floor slabs on frame stiffness
shall be considered.

13.1.9Column Splices
Splices in columns should be located within the middle half of the storey
height.

13.1.10

Weld Testing
All tension butt-welds between members shall be non-destructively
tested unlesss the rejection rate of completed welds is consistently lessthan 5 percent, in which case the testing rate may be reduced to 25
percent of the welds.

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613.2Ductile Braced Frames
13.2.1 General
Diagonally-braced frames for which a value of K = 2.0 or a steel bracing
member for which a valud K = 1.0 is to be used in the assessment of theearthquake design forces shall be detailed in accordance with 13.2.
13.2.2 Relative Strengths
Members, connections and foundations should be designed andproportioned so that the bracing reaches its actual yield load with anappropriate allowance for strain hardening before the associated columns
reach their buckling load or before any connections between members
and the foundations reach their ultimate strength. However, under nocircumstances shall either the columns or the connections be designed forless than 1.25 times the design actions in the braces, provided that theseactions need not be taken larger than those resulting from the use of
K = 4.

13.2.3Mixed Systems
Frames which resist horizontal loads by a mixed system of axially loaded
members and flexural members shall also comply with the requirementsof 13.1.

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7APPENDIX A
32NNEPAL
3130292825352740452642.5258082848688

MAP SHOWING HIGHEST MAXIMUM TEMPERATURE

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8APPENDIX B
32

NEPAL

N

3130

29-15

28-10-5027+2.526258082848688

MAP SHOWING LOWEST MINIMUM TEMPERATURE

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