Lecturenotes lesson2 design of steel industrial buildings

41 Design of steel structures II LESSON 2 DESIGN OF STEEL INDUSTRIAL BUILDINGS 42 CONTENT  Overview on steel structures  Design of single span steel portal frames  Design of wide span steel buildings  Design of multi storey steel buildings Lesson 2 – Design of steel industrial buildings  Overview on industrial buildings  Anatomy of a portal frame building  Column grid preliminary design of portal frame  Bracing  Main frame analysis  Gable analysis  Other secondary structural compone.

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LESSON 2 DESIGN OF STEEL INDUSTRIAL BUILDINGS

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CONTENT

 Overview on steel structures

 Design of single-span steel portal frames

 Design of wide-span steel buildings

 Design of multi-storey steel buildings

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 Overview on industrial buildings

 Anatomy of a portal frame building

 Column grid & preliminary design of portal frame

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Lesson 2 – Design of steel industrial buildings

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 Geometry

 Truss

 Portals in various types of

construction: built-up tapered

sections, lattice, cold-rolled steel

frames

 Arches in single section or lattice

construction

I OVERVIEW ON INDUSTRIAL BUILDINGS

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 Example of distribution of resultants of a steel frame:

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 Classification: type of industrial buildings according to the crane type:

 Q=0 - 30T

 Q=30 - 75T

 Q > 75T

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 Gable (end frame)

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 Cranes

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 Jack beams

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 Bracing

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 Purlins

Anatomy of industrial buildings

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 Roof monitors

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 Building envelope (cladding)

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 Column grid

 Preliminary design of portal frame

 Column height

 Column position according to the grid line

 Crane beam position according to the grid line

 Roof pitch

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 Continuous frame provides stability

in-plane, and the resistance to lateral

loads

 Frame spacing B between 6 m and 8m

 Span L from 15m to 50m: 18m, 21m,

27m, 30m,…

 A roof pitch between 5°and 10°

 A clear height (from the top of the floor

to the underside of the haunch)

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Given a construction area 15mx34m, plot a column grid

 Example

34m

15m

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 Height of the column:

 Preliminary design of portal frame dimensions

Column grid & preliminary design of portal frame

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Height of the column:

Htr=H2 + Hdc + Hr

 Hdc =1/8-1/10 : span of the crane beam

 Hr : height of the rail, 200mm

 Preliminary design of portal frame dimensions

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 Hd=H - Htr + H3

 H3 : part of the column

under ground,

H3=600 – 1000mm

 Preliminary design of portal frame dimensions

Height of the column:

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Position of the column according to grid line:

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Position of crane beam:

 > ( ht - a ) + D + B1 = ( ht - a ) + zmin

 zmin, B1 : crane catalogue

 D=60-75mm

 Preliminary design of portal frame dimensions

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 Roof bracing

 Column bracing

Bracing

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 Bracing required both in the plane of the rafters and vertically in the plane of the side walls

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 Longitudinal stability provided by a diagonal bracing

Bracing

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 Longitudinal stability can be provided by a rigid frame

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 Moving of wind load to the basement

Bracing

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 Example of roof and column bracings:

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 Image of roof and column bracings:

Bracing

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 Design scheme of main frame

 Load and action

 Computational methods of resultants

 Design of frame members

 Connections

Main frame analysis

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DESIGN SCHEME OF MAIN FRAME

 Function and restraints of the

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LOAD & ACTION

 Dead load:

• Cladding, bracing, purlin: gm = B qo daN/m

• Crane beams : gdct= dctLdct2, dct=24-27 với Q<75T và 35-47 với Q>75T

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 Construction of cladding in site

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 Finished image of cladding

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Glass fiber Mineral fiber

 Insulation materials

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PU : Polyurethane

 Cladding by roof panel

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 Purlin connection:

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Purlin bracing

 Design of purlins:

Flange brace

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 Connection of purlins and rafter:

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 Image of flange brace

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 Column purlin - Girt

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Truss purlin for long frame span:

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 CRANE LOAD: lifted load + seft weight of the crane, crab, hook

 Vertical action Dmax, Dmin derived from influence line principle

 Dmax = = n.nc.Pmax.yi , Dmin= n.nc.Pmin.yi

 n : importance factor (n=1,1), nc : crane combination coefficient (nc=0,85: 2 light and medium cranes, nc=0.95 for heavy crane)

 Pmax : maximum action of a wheel on the rail

 Pmin = (Q+G)/no – Pmax, no : number of wheels on a rail side, G – seft weight of the crane, Q – lifted load

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 Vertical action

 Dmax, Dmin : determined from influence line principle

 Eccentric moment : Mmax, Mmin

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 Wind load:

q=n W0 k c B

 n=1,2 : importance factor

 W0 : standard wind load

 k : coefficient taken into

account the variation of

wind load with the height z

 c : aerodynamic coefficient

 B: frame spacing

Aerodynamic coefficient C (Schemes 2 & 8 of TCVN 2737-1995)

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 Resume of load and action:

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 Resume of load and action

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 Load combination

 TCVN 2737 – 1995: 1 st and 2 rd basic load combination

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 Load and action

 Computational methods

 Connections

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 Process of Designing main frame

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 Preliminary sizing of column section

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 Preliminary sizing of rafter section

0.5 10.3 0.5

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 Design of column bracket:

2400.3 0.5

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 Modelling of main frame by finite element software:

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 Modelling framing on Sap 2000 software

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 Moment of framing with wind load

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 Load and action

 Computational methods

 Connections

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COLUMN VERIFICATION

Invariable column section

Variable column section

 Resultants : N, M, Q

Eccentric compressive column (N, M)Choose combinations as follows:

 Mmax, N   , Mmin, N   , Nmax, M 

 CHECK WITH ULTIMATE LIMITE STATE (ULS)

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 In-plane design length of column with invariable section:

n n

  



Column clamped with base:

 In-plane design length of column with variable section:

(7.5.2.1 - TCVN 5575-2012)

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µ0 : complementary design length coefficient (D.1.4 – TCVN 5575-2012)

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 Out-of-plane design length of column:

y y

l   H

ly : distance of two out-of-plane fixed points

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 Verification of limit slenderness:

 Verification of strength condition:

Note: 7.4.1.1, TCVN 5575-2012, don’t check strength condition if m e ≤ 20

 Verification of in-plane stability

e : determine at Table D.10, TCVN 5575-2012

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 Verification of out-of-plane stability

c : depend on mx , 7.4.2.5, TCVN 5575-2012

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 Verification of local stability

 Flange

 Web

Note: m e > 20, web stability follows 7.6.1, TCVN 5575-2012

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RAFTER VERIFICATION

Choose combination: |M|max, N, V

 In-plane design length of rafter:

 Out -of-plane design length of rafter:

ly: distance of two out-of-plane fixed points

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 Verification of strength condition

 Verification of local stability

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 CHECK WITH SERVICE LIMITE STATE (SLS)

 Allowable vertical displacement

(Table 1, TCVN 5575-2012)

 Allowable horizontal displacement

(5.3.3, TCVN 5575-2012)

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 Load and action

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 Connection with base

 Hinged connection

Base plate of dimension B x L x t : requirement of bending and contact

pressure of footing surface

Stiffener (if any): bending requirement

Anchor bolt : tension requirement

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 Clamped connection

Base plate of dimension B x L x t : requirement of bending and contact

pressure of footing surface

Stiffener : bending requirement

Anchor bolt : tension requirement

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 Standard anchor bolts

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 Standard anchor bolts: bolt material according to JIS-G3101 SS400

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 Connection of column and rafter – Knee connection

 Horizontal Knee connection details

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 Connection of column and rafter – Knee connection

 Vertical Knee connection details

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 Rafter splice

 Ridge splice details

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