Free Sample
Coastal Zone Development Portfolio Steel structures
Solution.pdf
TABLE OF CONTENTS
1. INTRODUCTION .................................................................................................................................................. 3
2.1 CALCULATIONS ................................................................................................................................................... 5
2.2 DRAWINGS ......................................................................................................................................................... 5
3. DESCRIPTION OF THE ASSIGNMENT ................................................................................................................... 5
4. STARTING POINTS OF STRUCTURAL DESIGN ......................................................................................................10
5. TASKS/ END PRODUCTS TO DELIVER .................................................................................................................12
6. PLANNING/ TIME SCHEDULE .............................................................................................................................14
7. ADDITIONAL INFORMATION .............................................................................................................................19
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1. INTRODUCTION
The structural portfolio of semester 4 consists of 2 parts, related to the steel and applied mechanics course of quarter 3 and 4. Both deal with the design of the steel structure of an industrial hall.
Difference between assignment of quarter 3 and 4
In principal in quarter 3 the complete steel structure will be worked out but in quarter 4 the structure will be made more complex. In the assignment of quarter 3 all structural elements are still all statically determined and as such can all be solved by only using the 3 equilibrium equations ΣH=0, ΣV=0, and ΣM=0. In quarter 4 the main (rafter) beams of the roof structure will be changed into statically indeterminate ones. To be able to calculate the internal forces in those beams additional theory regarding the deformation of the beam is needed which will be discussed in quarter 4.
The difference is illustrated in the two figures below. The left figure shows the main portal frames of the industrial hall in the assignment of quarter 3, the right figure the changed scheme of the frames in the project part of quarter 4. Notice the subtle difference of the position of the hinge (s) at the top side of the inner column: in the left figure the hinge at the top side of the inner column is located inside the beam; the beam is divided into 2 single span beams and is therefore statically determinate. In the right figure the hinge is located UNDERNEATH the beam, which indicates that at this location the beam is CONTINUOUS and only the connection between the beam and the column is hinging.
Now that the beam is continuous it has become a statically indeterminate element since there are now too many support reactions to calculate by only using the 3 equilibrium equations (ΣH=0, ΣV=0, and ΣMV=0). (In addition the quarter 4 assignment will also discuss some other changes in the structure, see the portfolio assignment of block 4 for more details).
(*) Vertical roller support models horizontal support at top side delivered by bracings in roof and side walls. Portal frame quarter 3:
Portal frame quarter 4:
Main beam is divided into 2
Main beam is fully continuous single span beams
S S
S (*) S S (*)
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S
Common jargon used in Structural Engineering
In the preceding courses all types of steel beams are just simply called “beams”. However, in practice different terms are used to describe different types of beams, depending on the type of structure that is being considered. Here the main structure of an industrial hall is discussed. The main (primary) beams of the roof structure are called “rafters”. The secondary beams are called “purlins”, and the horizontal beams in the side walls are called “side rails”.
(Some other terms for beams in civil structures: a horizontal beam being part of a strut frame of a sheet pile is called a “wale (beam)”. Further a very large primary/ mean beam of a bridge structure is called a “girder”.)
Figure: Arrangement of a typical single storey building
(see also website: https://www.steelconstruction.info/Single_storey_industrial_buildings)
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2. LEARNING GOALS OF STEEL COURSE PORTFOLIO
2.1 CALCULATIONS
Strength check:
Determine the cross-section resistance of members subjected to singular bending, shear, tension or compression based on elastic analysis and plastic analysis [Application]
Determine the cross-section resistance of members subjected to combined bending, shear, (and compression), based on elastic and plastic analysis [Application]
Stability check:
Stability of total structure:
Check the stability of braced frames [Application]
Stability of individual steel members:
Check the buckling stability of axial compression members [Application]
Check the lateral (torsional) buckling stability of members in bending [Application]
Stiffness check:
Check maximum vertical displacement of a steel beam (at mid-span or at end of overhang) [Application]
Check maximum horizontal displacement of a steel structure [Application]
Steel details:
Design a simple joint by just considering the bolds and welds [Application]
2.2 DRAWINGS
Make struct. drawing of a steel frame containing plane view, side views and cross-section(s) [Application]
Make structural drawing of steel frame containing most relevant steel connections/ joints [Application]
3. DESCRIPTION OF THE ASSIGNMENT
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You are working as a junior structural engineer at a construction agency. The new project that you are dealing with is the design of a steel structure for an industrial hall. The hall will be used to store ship’s provisions and will be located in the port area of municipality X.
Schedule of requirements – part 1 architectural
The schedule of requirements made up by the municipality of X contains the following demands:
a. Roof structure
The roof consists of steel roofing sheet panels which are supported by steel girders. On top of the steel roofing panels lies an insulation layer with a thickness of 100 mm. The insulation layer is covered by a bituminous roofing asphalt layer. The slope of the gable roof is 16 mm/m1 (from axis 3 to 1, and from axis 3 to 5) to ensure the water will drain off. The sloop will be included in the roof’s steel structure.
b. Facades – description of structure
The claddings are made of precast sandwich panels comprised of an aluminum sheet skin laminated over an EPS insulation core. These panels are oriented vertically and are supported in horizontal direction by side rails spanning in horizontal direction between the steel columns of the main structure.
c. Openings in faces
Each of the facades in axis 1 and 5 will have 2 openings for roller doors. The openings will have a width of 3 m and a height equal to 2 times “c ”. See figures on next page.
Schedule of requirements – part 2 structural
a. General
The assignment only consists of the design of the steel main structure of the industrial hall. The steel structure is braced in both longitudinal and cross-sectional direction. All connections between structural elements should be detailed as simple joints and as such should be considered to be hinges.
The primary structure consists of a series of parallel 2-span portal frames (with simple joints, including hinged column-bases). The frames are located on the grid axes A to F, the spacing between them is “2xa” meters, see figures. Each frame contains 3 columns: 2 side wall columns (in axis 1 and 5) and 1 column in the middle of the cross section, in axis 3. To reduce the span of
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the side rails half-way in between the side wall columns of the portal frames extra side columns are installed.
Column
Plane view of roof structure (horizontal bracings/ trusses in roof plane are not shown):
Inner portal frames
Extra side wall columns in between frames
Portal frames at front and rear end of building
(rafter modeled as a series of 4 single span beams)
Cross section of 2-span portal frames
View of frames at front and rear of building
(facades at the front and rear of the building.)
(vertical bracings are not shown)
(*)
Roof slope not shown in front and rear view
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rafter Roof pitch of 16 mm/m
side rails
purlins
1 51
edge purlin
column column
column 3
Vertical roller support Cross-section of 2-span portal frames
models horizontal support at top side delivered by
Scheme of portal frames:
bracings in roof and side walls S
S S b. Roof structure
Between the rafter beams of the portal frames purlins are spanning. On top of the purlins the steel roofing sheet panels are fixed. The roof structure contains horizontal bracings to obtain horizontal trusses for the transfer of the wind load to the vertical bracings in the side walls. Starting points is that the purlins are single span beams (and not continuous), and that the top flange (*) of the purlins is fully supported in horizontal direction by the roof sheets. The rafter beams are not support horizontally by the roof sheets, only by the purlins.
(*) Mind that wind load can also be acting (, inside the building,) in a vertically upward direction against the underside of the roof structure (!) Here a relatively light roof construction is used so that in case of an extreme storm the total resultant roof load might be directed upwards instead of downwards (!) (so that the lower flange will be compressed instead of the upper (!)). Note that in such situation the permanent load works favorable and should therefore be multiplied by 0,9 instead of 1,2 (or 1,35), resulting in the following ULS combination: 0,9*permanent – 1,5*wind (minus since wind load acts in opposite direction (!)) (roof can also be blown off the building (!) if hasn’t been fixed properly..)
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c. Structure of faces/ side walls.
As mentioned above the precast sandwich panels which span in vertical direction are fixed on the horizontal slide rails. Similar to the roof plane, the vertical side wall planes are also fully braced. It can be assumed that the weight of the precast sandwich elements in the side wall is fully carried by the foundation; no vertical load due to the self-weight of the claddings is acting on the side rails.
More information about claddings/ sandwich panels/ roof sheets https://www.sabprofiel.nl/ (Also in English) https://www.kingspan.com/nl/nl-nl
d. Requirements regarding deformation/ deflection at SLS
Maximum allowed vertical deflection of roof elements (beams of main frames, girders, and purlins): utotal< 1/250l (utotal= total deflection due to permanent load of roof structure and variable load on roof (rain/ snow/ wind/ inspection))
Maximum allowed horizontal displacement of columns and horizontal beams in side walls: Utotal <1/250h (utotal = horizontal deflection due to wind load acting on facings)
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4. STARTING POINTS OF STRUCTURAL DESIGN
a. Check of all structural elements should be applied according to Eurocode NEN-EN 1993-
1-1 (Eurocode 3) (*)
b. All joints should be considered as being hinged connections (also called pin ends joins,
or shear joints (beams in bending))
c. Steel grade S235 should be used for all structural elements
d. The magnitude of permanent and variable loads and de load combinations should be
determined on basis of Eurocode NEN-EN 1990 and NEN-EN 1991 (Eurocode 0 and 1).
e. The exact calculation of the wind load according to the codes is quite complex. To limit the complexity of the assignment a simplified approach will be followed. See appendix A for an overview of the wind loads that should be used.
(The building is located in wind area II, building site in wide open area)
f. The design working life of the industrial hall is 50 years
g. Consequent / reliability class (CC/RC): CC2 (**)
The ULS combinations of CC2 are:
[1] 1,2*permanent + 1,5*variable [2] 1,35*permanent + 1,5*Ψ0*variable [3] 0,9*permanent – 1,5* wind (in case of upward wind load on roof structure (!))
h. During the stability check of the total building - besides wind loads - also account should
be taken of an initial imperfection of 1/200. This imperfection should be considered in both longitudinal and cross direction. However to simplify this current portfolio assignment, these imperfection influences can be neglected/ will not be considered.
(*) With exception of simplified rules regarding lateral buckling check as discussed during course
(**) Normally an industrial hall corresponds to CC1, but here it is adopted that a part of the hall will be used as office space. In that case CC2 is valid.
Course material/ literature
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- All course material of Structural Engineering 2 and 3 (and all other preceding structural
courses)
- The Eurocodes:
o NEN-EN 1990 o NEN-EN 1991-1-1-1 o NEN-EN 1991-1-1-3 o NEN-EN 1991-1-4
- Computer programs TS beams and TS frames (also available on network of the HZ). Other similar programs are also allowed to use. (However computer calculations always need to be calibrated by hand calculations (this also counts for spreadsheet calculations like Excel)).
4.1 Groups
This assignment will be worked out in groups.
For each group the dimensions of the building will be different, see the table below.
Each group uses a different value for the dimensions a, b and c (see figure below, in meters).
Group nr. dimension a dimension b dimension c
1 3.70 3.70 2.75 2 3.80 3.80 2.70 3 3.90 3.90 2.65 4 4.00 4.00 2.60 5 4.10 4.10 2.55 6 4.20 4.20 2.50 7 4.10 3.70 2.50 8 4.00 3.80 2.55 9 3.90 3.90 2.60 10 3.80 4.00 2.65 11 3.70 4.10 2.70 12 3.60 4.20 2.75
For each group there is a shared responsibility for the end result.
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5. TASKS/ END PRODUCTS TO DELIVER
At the end of the assignment the following products must be handed in:
Calculation report of main structure
The calculation report should contain:
A1. A design calculation and check of the purlins.
A2. A design calculation and check of the rafters (the roof beam of the portal frames).
Determine also the cross-section classification of the beam section.
A3. A design calculation and check of columns of the 2-span portal frames (the 2 outer
columns in axis 1 and 3, and the inner column in axis 3.)
(To limit the scope the profile/section of the outer columns of the 2-span portal frames can also be used for the remaining columns in the side walls (the ones being blue colored in the figure above, and the columns in the front and rear wall in axis A and F)).
A4. A design calculation and check of the horizontal side rails.
A5. A design calculation and check of the stability elements of the total building, in both
longitudinal and cross-sectional direction. As said above the structure is fully braced, the stability elements are the horizontal trusses in the (horizontal) roof plane and the vertical bracings in the side walls. The dimensions of the diagonals of the bracings need to be determined.
(Further don’t forget that the transfer of the horizontal wind forces from the roof to the foundation will also result in a vertical compressive force in one of the columns of the vertical bracings in the side walls. Note that in these columns the total compressive force corresponding to the ULS load based on 1,2*permanent+1,5*wind might be larger than the compression due to 1,2*permanent+1,5*variable roof load. (*))
(*) the reduction factor Ψ0 is both 0 for wind and variable roof load so you don’t have to combine these 2 variable loads).
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Structural drawing (scale 1:100 or 1:50) containing
B1. A plane view of the steel roof structure
B2. A cross-section of the portal frames in axis B-E
B3. A (front) view of the steel structure in the front face and rear of the building
B4. A longitudinal view of the steel structures in the side walls
Structural drawings with details of steel joints (scale 1:10) containing
C1. Detail 1, 2, and 3 as shown in figure below
C2. Joint of diagonal member of vertical bracings (in side walls) with connecting structural
members.
Roof pitch of 16 mm/m
Det 1
purlins rafter Det 2
edge purlin
side rails
column column column Det 3
1 3
51
Cross-section of 2-span portal frames
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6. PLANNING/ TIME SCHEDULE
Supervision, guidance, and additional theory will be given during the working lessons of the steel course.
Therefore be all present during these working lessons!
Week Topics
Discussed during working lesson
Milestones (only the ones of the calculations are given) 1 - Starting points vertical loads on roof structure
- Internal forces purlins - Check strength and stiffness purlins
- Starting points horizontal loads on side rails - Internal forces side rails - Check strength (/cross-sectional resistance) and stiffness side rails
(First estimation) section purlins (1) Selection side rails (1)
2 - Vertical loads rafter beam
- Internal forces rafter beam - Check strength and deformation of rafter beam
- Defining position of trusses/bracings - Scheme horizontal roof trusses - Scheme vertical roof truss
(First estimation) section of rafter beam (2)
3 - Internal forces trusses
- Internal forces columns - Check tensile members trusses
Section of diagonals trusses (bracings)
3 - Check buckling stability of columns axis 3 Section of columns axis 3
4 - Lateral buckling stability check of purlins
- Lateral buckling stability check of rafter beam
Final selection section rafter beam Final selection section purlin beam
5 - Check combination buckling and lateral buckling of
columns axis 1 and 5 (3)
Section side wall columns axis 1 and 5
6 -Details Sketches of details 7 -Details/ finishing works Finishing/ submission of
portfolio
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Additional remarks on calculation process:
(1) First estimation only based on strength and stiffness (=deflection) check. A lateral buckling
check is not relevant in case of snow, rain or service and repair (inspection etc) load on roof, since resultant total load acts downwards resulting in a positive moment and compression in top flange which is supported in cross-sectional direction by roof sheets. But lateral buckling might happen in case of an upward directed wind load (wind inside building acting vertically, upwards, against underside of roof). The ULS combination [0,9*permanent – 1,5*wind] should be considered. If the resultant total load based on this ULS combination appears to be directed upwards (is negative), than the corresponding M-line will be upside down: at mid-span a negative moment will occur. In other words the lower flange will be compressed which is not being supported by the steel roof sheets (!!!) so that this flange might buckle laterally. In other words in case of wind load also lateral buckling stability check of purlins needs to be made. See also illustration below.
Situation 1: Variable roof load representing snow, rain, or people:
Horizontal support modelled by vertical roller Scheme of purlin and M-line:
- + Situation 2: in case of a light roof structure and extreme wind, resulting load might be upwards:
+
- Compressed bottom flange not
supported horizontally! Can move sideward, rotate; can buckle laterally: (stability) check needed!
Steel roof sheets stabilize the purlins, horizontal movement of the compressed top flange is prevented along full length of beam: lateral buckling cannot occur
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Regarding the side rails beams: it can be assumed that the side rails cannot buckle laterally due to the support by the sandwich panels, see figure below (in theory in case of wind on the leeward side (suction), wind is in opposite direction and side rail can buckle but this will not be considered to simplify assignment).
Compressed flange is fixated -> section Sandwich panel spanning in
cannot buckle laterally vertical direction, supported in horizontal direction by side rail beams Wind direction (windward side)
Inside (2) Again first estimation only based on strength and stiffness (=deflection) check. However note that the top flange is NOT being supported in cross-sectional direction (along full length) by the roof sheets so that also a lateral buckling stability check of the rafters is needed in addition. (The rafter is supported in cross-sectional direction, but not by the roof sheets, but just locally by the connecting purlins).
(3) Loads on side wall columns in axis 1 and 5:
Scheme of columns:
NEd
Fwind;Ed
Fwind;Ed
Fwind;Ed
NEd MEd
Side rail
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Note that in case of wind load the side columns are subjected to both bending and axial compression. When considering the stability of these columns, the following formula should be used which combines the influence of both buckling and lateral (torsional) buckling:
1,1 ? (χLT MEd
? Wy ? fyd) + 1,1 ? (χ ? NA Ed
? fyd) ≤ 1,0
This formula is taken from the old Dutch steel code NEN6770 which preceded the current Eurocode 3. It’s a simplified, conservative approach and therefore still applicable. This equation is used to avoid using the very complex formulas of the current Eurcode 3. See additional literature for more information.
(This combined bending + axial compression load case will only be discussed in this project, will NOT be considered in the written exam of this steel course (!))
Question: what is the best position of the side wall columns when using HE-sections:
Note remark about side wall columns being part of vertical bracings which might have a higher compression load due to transfer of wind load from roof to foundation. This is will have to be checked in addition. Wind
Wind
direction (windward side)
direction (windward side)
Outside Inside Outside
Inside
Side wall
OR
Side wall
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Date at which the assignment must be be handed in
→ See Learn page of semester project
Please check completeness of required documents and drawings before handing in!
If the total set of calculations and drawings is not complete, it won’t be graded. In that case you will miss the first attempt and as a result you will only have left the resit opportunity. (And if you fail for the second assessment you will have to do the project assignment all over again next year!)
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7. ADDITIONAL INFORMATION
Specific guidelines for the calculation report
- Mention how the project assignment is distributed among the group members; describe for each member what his or her contribution is to the end result
- Be sure that the calculation is readable. The set-up of the calculation has to be logical and clear, all successive steps of a design calculation or check of a structural member must be written in full, providing only the end results will not be accepted. To get an indication how to set-up a calculation see the various calculations in the power points and pdf’s of the SE1, SE2 and SE3 course. If in a certain part of the calculation results are used from another part always refer to that other part so that it is always possible to verify where values of calculation parameters are based on/ can be found.
A calculation should always start with an overview of the corresponding starting points. An important part of this is an overview of the loads. Make for each load case (permanent load, variable loads) and load combination (at SLS and ULS) a short calculation of the uniform load per m2.
Example: vertical loads acting on roof plane:
Roof: permanent load
Self weight of steel roof sheets 0.15 kN/m2
Self weight of insulation and roof finishing 0.25 kN/m2 +
Total 0.40 kN/m2
Roof: variable load 1: snow load
Snow load 0.56 kN/m2 (Ψ0 = 0)
Here 0.56 kN/m2 is a constant uniform load acting across the complete roof area because the industrial hall contains a flat roof and there are no surrounding taller buildings nearby. Be aware that snow load can be significantly larger in other circumstances (!), see Eurocode.
Furthermore the above mentioned specific value of 0.56 kN/m2 is valid for the Netherlands. In other countries where in general colder winters occur, for instance Austria, more heavy snow loads should be used, see National Annex of such countries.
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Roof: variable load 2:
- load due to persons/ equipment etc. related
to inspection/ maintenance. 1.0 kN/m2 (max area of 10 m2) (Ψ0 = 0)
Roof: variable load 3:
- load due to rain fall: depending on roof slope and amount of water discharge pipes are used. Here it can be assumed that rain load is at max equal to snow load of 0,56 kN/m2
(=starting point roof drainage system)) (Ψ0 = 0)
Roof: variable load 4: Vertical component of wind loads:
see appendix A (Ψ0 = 0)
As shown in the various power points of the structural courses, a calculation of a structural member (beam, column, etc.) contains the following successive steps:
Check 1 and 2, check of strength and stability, should always be made on basis of the decisive load combination at ULS.
Check 3: check of deflection/ deformation should be made by using the decisive load combination at SLS. In this current assignment the characteristic combination should be used.
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The following table provides an overview of the various checks which have to be done for the structural members of the hall:
Cross section resistance (Strength)
Lateral (torsional) buckling stability
Buckling Stability
Deflection (Stiffness)
Member: (inner) and edge purlins
X X (wind) X
Rafter beam of main portal frames
X X X
Side rails X X Inner columns of main portal frames (axis 3)
X
Edge columns of main portal frames in side walls (axis 1 and 5)
X (wind) (*) X (*)
Diagonal tensile members of bracings (in roof and side walls)
X
Compressed members of bracing structures (**)
X
(*) Use combined equation lateral buckling and buckling, see previous explanation.
(**) Columns of vertical side wall bracings, see figure (Note that also the top chord of the horizontal roof truss is also compressed and as such can also buckle (!) Often this is the edge purlin. To simplify and limit the scope of this current assignment this check can however be neglected).
Vertical bracing in side walls
Fwind
Compression in column due to transfer of wind load from roof to GL
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Choice of profile: which section profile can be used best in which circumstances?
A comparative study of about equally heavy (= kg/m') and thus equally expensive profiles.
Based on the value of Iy and Iz of the profiles below it can be concluded that:
IPE400
mass: 66,3 kg/m
Iy: 23130 cm4
Iz: 1318 cm4
Bending.
HE260A
68,2 kg/m
10450 cm4
3668 cm4
Bending.
HE220B
HE220B
71,5 kg/m
71,5 kg/m
8091 cm4
8091 cm4
2843 cm4
2843 cm4
Bending.
Bending.
HE140M
HE140M
HE140M
63,2 kg/m
63,2 kg/m
63,2 kg/m
3291 cm4
3291 cm4
3291 cm4
1144 cm4
1144 cm4
1144 cm4
Bending.
Bending.
Bending.
Tube 300x300x7.1
Tube 300x300x7.1
Tube 300x300x7.1
Tube 300x300x7.1
63,9 kg/m
63,9 kg/m
63,9 kg/m
63,9 kg/m
11516 cm4
11516 cm4
11516 cm4
11516 cm4
11516 cm4
11516 cm4
11516 cm4
11516 cm4
Bending
Bending
Bending
Bending
Very suitable for bending around the
y-axis:
largest Iy of all to compare profiles.
Problem of lateral buckling has to be solved, if this profile has to be used optimally!
If, in connection with lateral buckling, a HEA is more favourable.
Has a small Iy and Iz (costs a lot of steel for the same I in relation to IPE and HEA (when comparing equal weighted sections (!)).
Has a small Iy and Iz (costs a lot of steel for the same I in relation to IPE and HEA (when comparing equal weighted sections (!)).
Has a small Iy and Iz (costs a lot of steel for the same I in relation to IPE and HEA (when comparing equal weighted sections (!)).
Has a small Iy and Iz (costs a lot of steel for the same I in relation to IPE and HEA (when comparing equal weighted sections (!)).
Interesting when HEA section is no option due to height restrictions
Has even a smaller Iy and Iz.
Has even a smaller Iy and Iz.
Has even a smaller Iy and Iz.
(costs more steel for the same I in relation to IPE and HEA).
(costs more steel for the same I in relation to IPE and HEA).
(costs more steel for the same I in relation to IPE and HEA).
(costs more steel for the same I in relation to IPE and HEA).
(costs more steel for the same I in relation to IPE and HEA).
Interesting when HEA or HEB section is no option due to height restrictions
Interesting when HEA or HEB section is no option due to height restrictions
Advantage is that section cannot buckle laterally.
Advantage is that section cannot buckle laterally.
Advantage is that section cannot buckle laterally.
Advantage is that section cannot buckle laterally.
Advantage is that section cannot buckle laterally.
Advantage is that section cannot buckle laterally.
Downside is that connections with other profiles are more expensive (compared to those of HE- and IPE sections)
Downside is that connections with other profiles are more expensive (compared to those of HE- and IPE sections)
Downside is that connections with other profiles are more expensive (compared to those of HE- and IPE sections)
Downside is that connections with other profiles are more expensive (compared to those of HE- and IPE sections)
Downside is that connections with other profiles are more expensive (compared to those of HE- and IPE sections)
Downside is that connections with other profiles are more expensive (compared to those of HE- and IPE sections)
Furthermore boxed sections are somewhat more
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Axial compression.
If the problem of buckling around the weakest axle is solved: IPE has around the strongest axle the largest resistance against buckling: the largest Iy.
Deflection.
The largest resistance against deflection (around the strongest axle): the largest Iy.
expensive than H- and IPE sections)
Torsion.
Boxed sections are most interesting to use as beams in case of torsion. Boxed sections are closed sections and as such have a large resistance against torsion. (H- and IPE sections are open and have much worse resistance against torsion.)
Axial compression.
Axial Compression.
Axial Compression.
Axial Compression.
Suitable as detached column: largest Iz of the
Suitable as detached column: largest Iz of the
I-shaped profiles.
I-shaped profiles.
Axial Compression.
Axial Compression.
Axial Compression.
Axial Compression.
Interesting when compact column is required and buckling about z- axis is not decisive
Interesting when compact column is required and buckling about z- axis is not decisive
Interesting when compact column is required and buckling about z- axis is not decisive
Interesting when compact column is required and buckling about z- axis is not decisive
Interesting when compact column is required and buckling about z- axis is not decisive
Axial Compression.
Axial Compression.
Axial Compression.
Axial Compression.
Axial Compression.
Interesting when even more compact columns is required and buckling about z- axis is not decisive.
Interesting when even more compact columns is required and buckling about z- axis is not decisive.
Interesting when even more compact columns is required and buckling about z- axis is not decisive.
Interesting when even more compact columns is required and buckling about z- axis is not decisive.
Interesting when even more compact columns is required and buckling about z- axis is not decisive.
Interesting when even more compact columns is required and buckling about z- axis is not decisive.
Very suitable as detached column:
largest Iz value.
UNP: Connects very easily because of one flat side. Applied as an edge beam for a roof (has only about half of the load in relation to other roof beams) in relation to the mounting of the facade. Does not so much inferior (concerning the Iy) to an IPE with the same height. With bending this profile has the tendency to rotate because of its a-symmetric shape; profile has a very low resistance against lateral buckling. Therefore it is often only used as a load bearing beam when lateral buckling is being prevented by fixating the compressed beam in horizontal direction with a stiff floor plane.
Conclusions
High profiles with a lot of material in the ”extreme fibre” have a large moment of inertia (I).
A large ratio between I and the amount of used kg’s steel gives the profile a high efficiency.
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APPENDIX A WIND LOAD
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Starting points (to simplify approach these values are used for the industrial hall of all groups):
Height of building = 8.5 m Width = 4x4.2 = 16.8 m Length = 10x4.2 = 42 m
Wind area II, wide open area without buildings -> qp,z = 0.81 kN/m2
Wind load to use in calculations (characteristic values, without safety factors. Influence of openings in facades are neglected):
Stability calculation of total building:
Total horizontal wind load against facades
qwind;kar = 0,81*(0,8+0,5)*0,85 = 0,90 kN/m2
Wind pressure is constant/ uniformly distributed along height of building.
Friction along roof and side wall area: is neglected to simplify calculations (relative contribution to total wind load is often small in case of small buildings, but can be significant in case of large buildings with a large roof and side wall area)
Maximum local wind load on side wall column/ side rail qwind;kar = 0.81*(0.8+0.3) = 0.89 kN/m2
Windpressure is constant/ uniform along height of building.
Maximum local upward wind load against underside of roof qwind;kar = 0.81*(0.7) = 0.57 kN/m2
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