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Structural Design of a Building
Extended Abstract
Miguel Ramos Benfica de Melo
March 2015
1
Structural Design of a Building
Extended Abstract
1 - Introduction
This thesis presents the development of a
building’s structural design. The scope of this
work is to create a structural solution that
ensures the safety of the building when facing
regulatory actions.
The study object is destined to be a warehouse
and a parking lot, in the area of Lisbon. It is
characterized by a considerable area with an
implantation area of approximately 15500 m2
and a total construction area of approximately
64000 m2. It has in its major extent 180 m and
120 m in the perpendicular direction. It features
two underground floors and two others above
ground floor, with a reduction of plan area of
approximately 38% from the ground floor to the
upper floors. The underground floors are
surrounded by an earth retaining wall. The two
underground floors are destined for parking lot
(𝐴 = 2 ∙ 15435 = 30870 𝑚2) and the next two
floors for warehouse (𝐴 = 15435 + 8857 =
24292 𝑚2). The roof (𝐴 = 8857 𝑚2) was
considered not accessible except for normal
maintenance and repair.
Figure 1: Building’s geometry
The goal of this work was to understand the
applicability of the theoretical knowledge
platform gained over the Instituto Superior
Técnico’s Structural Engineering course to the
practical activity of structural design.
Therefore, the different phases of a building’s
structural design, from its initial conception to
the final design, will be presented in this paper,
giving more emphasis in the determination of
the slab solution.
2 - Actions and combination of
actions
Structural analysis must consider the influence
of all actions that might produce significant
stress or strain to the structure’s safety.
Permanent and variable actions in the
structure were considered.
Regarding the permanent actions, apart from
the self-weight of structural elements, imposed
loads of 2,0 kN/m2 for the traffic and storage
areas and 2,5 kN/m2 for the coverage were
considered.
Regarding the variable actions, according to
the regulations, for traffic areas (Category F),
the imposed loads to be used are 4 kN/m2. For
areas of storage (Category E1) and for roofs
(Category H), an imposed load of 10 kN/m2
and 0,44 kN/m2 were used, respectively.
For the seismic action (SA), considering the
study case with an importance class of II and a
ground type B, and that Lisbon is situated in a
seismic zone of 1.3 and 2.3 respectively for
type 1 and 2 response spectra, the values that
2
define the response spectrum used in the
analysis are presented in the following table:
Table 1: Seismic parameters for Lisbon (EC8-1) with ground type B
Parameters SA
Type
SA
Type
𝑆𝑚𝑎𝑥 1,35 1,35
𝑇𝐵 (s) 0,1 0,1
𝑇𝐶 (s) 0,6 0,25
𝑇𝐷 (s) 2,0 2,0
𝑎𝑔𝑅 (ms-2
) 1,5 1,7
𝑎𝑔 (ms-2
) 1,5 1,7
𝑆 1,292 1,268
Regarding the temperature action, according to
the EC-1, Lisbon is situated in the B thermal
zone, which gives different values of
temperatures depending on the exposure of
the elements and the time of the year. The
uniform temperature represents the difference
between the temperature of the element due to
climate effects and the initial temperature of
the element. Respectively for the traffic area,
storage area, roof and for the earth retaining
wall, the uniform temperature values used in
this work are -2°C, -6°C, -6°C and -2°C, which
are relative to the winter season. The summer
season’s values were not used so the effect of
negative uniform temperature could be
combined with the effect of shrinkage of
concrete.
Safety verification criteria to Ultimate Limit
State (ULS) and Serviceability Limit State
(SLS) were adopted in the structure analysis
and design, according to the European
structures regulation, the Eurocodes, namely
Eurocodes 0, 1, 2 and 8 (EC0, EC1 and EC8,
respectively).
In accordance with the recommendations in
the Eurocodes, different combinations of
actions were considered for the analysis of
ULS and SLS. For ULS two combinations were
adopted, the fundamental combination
(𝐸𝑑 = 𝛾𝐺,𝑗 ∙ 𝐺𝑘,𝑗𝑗>1 " + "𝛾𝑄,1 ∙ 𝑄𝑘,1" +
" 𝛾𝑄,𝑖 ∙ 𝛹0,𝑖 ∙ 𝑄𝑘,𝑖𝑖>1 ) and the combination of
actions for seismic design situations (𝐸𝑑 =
𝐺𝑘,𝑗𝑗>1 " + "𝐴𝐸𝑑" + " 𝛹2,𝑖 ∙ 𝑄𝑘,𝑖𝑖>1 ).
Concerning the SLS, the quasi-permanent
combination was used (𝐸𝑑 = 𝐺𝑘,𝑗𝑗>1 " +
" 𝛹2,𝑖 ∙ 𝑄𝑘,𝑖𝑖>1 ).
For the seismic action, the directional
combination used a combination of 100%
response to one direction with 30% to the
perpendicular direction.
3 - Materials and ground
resistance
The materials adopted were C25/30 for
concrete and A500 NR SD for ordinary rebar.
Considering exposure classes of XC4, rebar
cover was considered to be 35 mm for slabs
and 40 mm for the rest of the structural
elements. Also, for this class of exposure, the
regulations limit the crack’s maximum opening
to 𝑤𝑚𝑎𝑥 = 0,3 𝑚𝑚.
According to the available data, the terrain’s
design admitted stress was considered to be
𝜎𝑎𝑑𝑚 = 300 𝑘𝑁 𝑚2 . Therefore the terrain’s
stress resistance is given by 𝜎𝑅𝑑 = 1,5 ∙ 𝜎𝑎𝑑𝑚 =
450 𝑘𝑁/𝑚2.
4 - Determination of the slab
solution
For this case of study, a grid of columns was
adopted of 8,10 m by 8,10 m. The first step of
this project was to define a slab solution that
combines construction speed and economical
prices. Therefore, four types of slabs were
studied: light weighted waffle slab with
recoverable molds, beam-supported slab, flat
3
slab with constant thickness and flat slab with
drop panels. The analysis for the determination
of the slab solution has been made for each
type of floor usage of the building, namely, for
the parking area, for the storage area and for
the roof slab.
For each type of slab, a parametrical analysis
has been made to calculate costs of materials
(concrete and steel rebar) and formwork
system, by changing its geometrical
parameters. In the following table are
presented the costs of materials used in this
analysis.
Table 2: Material costs
Material Costs
Concrete €/m3 100
Rebar (ϕ8) €/ton 850
Rebar (ϕ10) €/ton 820
Rebar (ϕ12) €/ton 800
Rebar (ϕ16) €/ton 795
Rebar (ϕ20) €/ton 795
Rebar (ϕ25) €/ton 805
Should be noted that this analysis was only
made for the fundamental combination of
action. Therefore, there were not considered
the effects of the seismic action which have a
considerable importance in slab’s stresses.
Also, the effect of uniform temperature and
concrete shrinkage were not considered
because they depend of the structural solution
that was chosen, and these analysis only
consider an interior slab panel.
For the case of the light weighted waffle slab,
800 mm by 800 mm recoverable molds were
used, with heights of 200 mm (M200), 300 mm
(M300) and 400 mm (M400). A 90 mm thick
topping slab was considered for all waffle slabs
that were analysed. Between columns, a band
beam was used, with the same depth as the
ribs. On top of columns, a head column was
used, also with the same depth as the ribs.
Regarding the narrow ribs spanning in both
directions, widths of 165 mm, 190 mm and 210
mm were used, respectively for molds of 200
mm, 300 mm and 400 mm.
Figure 2: Light weighted waffle slab plan
Figure 3: Light weighted waffle slab geometry
A finite element model of an internal slab panel
was created for each mold dimension and for
each floor occupation (parking floor, storage
floor and roof floor), which makes a total of 9
models. Stresses, rebar quantities, costs of
materials and formwork systems were
calculated to determine the less expensive
type of mold for each type of slab use, so it
could be compared with the others slab
solutions. In the following table are presented
the less expensive waffle slab dimensions for
each floor occupation and their respective
costs, without and with formwork system costs.
Table 3: Dimensions and respective costs of waffle slabs for each floor occupation
Floor Mold
Costs (€/m2)
w/o
formwork
w/
formwork
Parking M300 50,04 72,85
Storage M400 64,69 87,50
Roof M200 42,99 65,80
4
For the case of the beam-supported slab, a
parametric analysis was made to calculate
stresses and rebar required for different
combinations of slab thickness (𝑒), beam depth
(ℎ) and beam width (𝑏). As a simplification, first
was determined the less expensive slab
thickness in terms of costs of materials
(concrete and rebar). Then, the combination of
beam depth and width with less material costs
was determined. In this analysis, slab
thicknesses of 0,20 m (ℎ = 𝐿 41 ) to 0,30 m
(ℎ = 𝐿 27 ) were analysed, with increments of
1 cm between each thickness, making a total
of 11 possibilities. Regarding the beams,
widths went from 0,25 m to 0,50 m with
increments of 5 cm between each width. For
each width, beam depths of 0,40 m (ℎ = 𝐿 20 )
to 0,80 m (ℎ = 𝐿 10 ) were analysed, with
increments of 5 cm between each depth, which
made a total of 54 combinations of different
depth and width beams. In the following table
are presented the less expensive dimensions
and respective costs of beam-supported slabs
for each floor occupation, without and with
formwork system costs.
Table 4: Dimensions and respective costs of beam-supported slabs for each floor occupation
Floor
Slab geometry Costs (€/m2)
𝒆
(m)
𝒃
(m)
𝒉
(m)
w/o
formwork
w/
formwork
Parking 0,20 0,25 0,70 34,18 57,07
Storage 0,23 0,30 0,80 40,94 64,78
Roof 0,20 0,25 0,60 31,65 53,33
For the case of the flat slab with constant
thickness and for the one with drops, a similar
analysis was made. For both, an equivalent
frame analysis was used to determine stresses
in the slab.
For the flat slab with constant thickness,
thicknesses of 0,20 m (ℎ = 𝐿 40,5 ) to 0,35 m
(ℎ = 𝐿 23 ) were analysed, with increments of
1 cm between each thickness, which makes a
total of 16 possibilities. Regarding the slab with
drop panels, the minimal slab thickness used
(ℎ1) was 0,19 m and the maximal was 0,28 m.
Thicknesses with increments of 1 cm have
been analysed between those limits. For the
drop thickness (ℎ2), values of 0,30 m, 0,35 m
and 0,45 m were analysed. For the plan
dimensions of the drop (𝑎), widths of 2,0 m to
3,6 m were analysed, with increments of 10 cm
between each width. As result, 510 possible
combinations of different geometries were
analysed for the slab with drop panels.
For both flat slabs, the costs of materials were
calculated ensuring that the vertical
displacement at mid-span would be less than
𝐿′ 250 , with 𝐿′ = 2 ∙ 8,102 = 11,46 𝑚, for the
quasi-permanent combination of actions. The
geometries that wouldn’t respect that last
criteria, would not be accepted. The elastic
vertical displacement was multiplied by 5 to
take in account the effect of cracking and
creep.
The following table presents the less
expensive dimensions and respective costs of
flat slabs with constant thickness for each floor
occupation, without and with formwork system
costs.
Table 5: Dimensions and respective costs of flat slabs for each floor occupation
Floor Thickness
(m)
Costs (€/m2)
w/o
formwork
w/
formwork
Parking 0,25 57,94 74,29
Storage 0,32 76,27 92,62
Roof 0,22 46,61 62,96
The following table shows the less expensive
dimensions and respective costs of flat slabs
5
with panel drops for each floor occupation,
without and with formwork system costs.
Table 6: Dimensions and respective costs of flat slabs with panel drops for each floor occupation
Floor
Slab geometry Costs (€/m2)
𝒂
(m)
𝒉𝟏
(m)
𝒉𝟐
(m)
w/o
formwork
w/
formwork
Parking 2,80 0,19 0,40 42,00 58,94
Storage 3,40 0,22 0,40 54,98 71,94
Roof 3,00 0,19 0,40 36,27 53,25
Figure 4 – Flat slab with panel drops geometry
Taking in account the areas of each floor, the
costs of each slab solution per m2
of
construction area are presented in the next
figure, for the all structure, without and with
formwork system costs. Regarding the -2
floor’s slab, a 0,20 m thick slab was used,
which does not participate in the costs
presented below.
Taking in account only the costs of materials
and formwork system, the beam-supported
slab is the less expensive slab solution.
However it is a solution which requires a longer
construction time than the other slab solutions.
It is also a solution that interferes considerably
with the building’s equipment. For those
reasons, the flat slab with drop panels, the
second less expensive slab solution, has been
chosen for the design of the structure.
Should be noted that in the roof floor, the flat
slab with drops has bigger dimensions than the
parking floor’s slab, even though it has smaller
loads. In the parametric analysis resulted less
expensive rebar distribution in the roof slab
than for the parking floor, that combined with
bigger geometric dimensions, results in lower
total costs.
However, this parametric analysis has only
been made for the fundamental combination of
actions and for an interior slab panel.
Considering that in the overall structural
analysis, all the actions will be considered, and
with that, required rebar sections will change,
adopting bigger dimensions for the roof slab
than for the parking slab is not reasonable
anymore. For that reason, same dimensions
than the parking flat slab have been adopted
for the roof flat slab.
Figure 5: Slab solution’s costs
5 - Structural solution
Having determined the slab’s solution, the
resolution of the rest of the structure is as
follows. It consists in choosing the size and
56
,08
37
,10
65
,04
47
,45
78
,89
60
,24
81
,39
64
,40
0,00
20,00
40,00
60,00
80,00
100,00
Costs (€/m2)
Without formwork system costs
With formwork system costs
6
arrangement of the different structural
elements that guarantees the safety of the
building, its comfort and proper functioning.
Due to the size in plan of the building, imposed
deformations caused by uniform temperature
and shrinkage of concrete cause high stresses
in vertical elements. For that reason, an
expansion joint was used in the building.
However, expansion joints are inconvenient for
the building’s maintenance, due to water
infiltrations, and to functional quality in the
interior of the building. It has also its limitations
to fire resistance, so elevated lengths of
expansion joints were avoided.
Due to uniform temperature and shrinkage of
concrete, the farther vertical elements of the
building, in the inferior floors, suffer higher
deformations. To reduce those deformations
and also to avoid elevated lengths of
expansion joints, partial expansion joints were
used, as shown in the following figure. It
consists in using expansion joints in the inferior
floors, and with that, avoiding having those
systems in the roof floors, reducing water
infiltration problems due to precipitation. In this
case study, partial expansion joints were used
in all floors except in the roof floor.
Figure 6: Example of structure with partial expansion joints
Due to the fact that flat slabs have a poor
seismic behaviour, structural walls have been
added to the structure. Because of flat slabs
poor behaviour to seismic activity, regulation
recommends to use slabs and the interior
columns as secondary seismic members. To
consider those elements as secondary seismic
members, their lateral rigidity has to be less
than 15% of the total lateral rigidity of the
primary seismic elements.
The orientation of the structural walls in the
structure had to be taken in account. To assure
resistance to the structure, without restricting
imposed deformations due to uniform
temperature and shrinkage of concrete, walls
have been placed with their major axis of
inertia perpendicular to the edge of the nearest
floor’s edge.
To add more resistance to the seismic actions,
in the contour of the superior floors, a beam
has been added. The beam’s pre-design was
based on the condition that the value for “beam
height/span” must be around 𝐿 10 . To control
the beam’s stresses and with the estimated
beam’s height obtained, the normalized
moment, 𝜇, given by 𝜇 = 𝑀𝑆𝑑 𝑏 ∙ 𝑑2 ∙ 𝑓𝑐𝑑 ,
have been limited to 0,25, according to the
influence areas of the beams.
For column’s pre-design, according to their
influence area and for the fundamental
7
combination of actions, the area required for
each column has been obtained by limiting its
axial stresses as indicated in the following
expression, with 𝜈 = 1,0 for columns with low
ductility requirements (secondary seismic
elements) and 𝜈 = 0,8 for columns with high
ductility requirements (primary seismic
elements).
𝐴𝑐 ≥ 𝑁 𝜈 ∙ 𝑓𝑐𝑑 1
To pre-design stand-alone foundations, it was
insured that the terrain was able to withstand
the transmitted stresses. Calculating the axial
force at the base of the columns, for the
fundamental combination of actions, according
to their influence area, the minimum area of
the foundations (𝐴 ∙ 𝐵) have been determined
according to 𝐴 ∙ 𝐵 ≥ 𝑁𝐸𝑑 𝜎𝑅𝑑 .
Moments in the stand-alone foundations would
be absorbed by tie beams that would link every
element, so the standalone foundations could
be designed for axial force only.
Regarding the earth retaining wall, two
thicknesses have been adopted, one for each
underground floor, in such way that its
resistance to shear actions would withstand
the earth loads on it.
6 - Structure model
Since structural design is currently based on
the application of automatic data processing
tools, the three-dimensional finite elements
program SAP2000, has been used to model
the building’s structure. Columns and beams
were simulated as finite bar elements with two
nodes, one at each end, with six freedom
degrees each. Slabs and the earth retaining
wall were simulated with finite shell elements
with 3 and 4 nodes, also with six freedom
degrees each.
The effect of shrinkage of concrete was
simulated with an equivalent uniform
temperature to the structural elements, 𝛥𝑇𝑒𝑞,
according to the following expression.
𝛥𝑇𝑒𝑞 =𝜀𝑐𝑠𝛼
2
To take in account the effects of imposed
deformations (uniform temperature and
shrinkage of concrete), the concrete’s elastic
modulus, 𝐸𝑐,28, can be adjusted as indicated in
the following expression, where 𝜑 = 2,5, and
𝜒 = 0,8 for the shrinkage effect and 𝜒 = 0,4 for
the uniform temperature effect.
𝐸𝑐,𝑎𝑗 =𝐸𝑐,28
1 + 𝜒 ∙ 𝜑
3
To model this effect without affecting the
concrete’s elastic modulus in the material
properties of the program, the actions of
uniform temperature and shrinkage (𝛥𝑇𝑒𝑞) have
been affected with coefficients of 0,50 and 0,33
respectively.
The rigidity of structural elements has a major
influence in the response of the structure.
Beyond influencing the deformation of the
structural elements, it also affects the
structure’s vibration frequency, and with that,
the value of the seismic action.
To take in account the effect of concrete’s
cracking, structural elements flexural rigidity
have been affected with a coefficient of 50%,
as indicated in the EC8-1 for linear analysis.
For the interior columns of the slab, considered
as secondary seismic elements, a more
precise method has been adopted because of
their higher sensitivity to seismic actions. An
effective rigidity, 𝐸𝐼𝑒𝑓𝑓, indicated in the
following expression, have been adopted for
8
these elements, with 𝜈 = 1,20 and 𝜙𝑦 =
2,1 ∙ 𝜀𝑠𝑦 𝑑 , according to the regulations.
𝐸𝐼𝑒𝑓𝑓 =𝜈 ∙𝑀𝑅𝑑
𝜙𝑦 4
To simulate this effective rigidity, in the
columns section properties, the moment of
inertia factors took values of 𝐸𝐼𝑒𝑓𝑓 𝐸𝐼0 , with 𝐼0
being the non-cracked column’s moment of
inertia.
7 - Seismic analysis and design
calculation
The frequencies and mass participation factors
(Ux, Uy and Rz) for the first three vibration
modes (shown below) are listed in the
following tables.
Table 7: Mass participation factors - translatory movement in the x direction (first three vibration
modes)
Mode Per. (s)
Freq. (Hz)
Translatory mov. x
Ux ∑Ux
1 0,539 1,855 0,478 0,478
2 0,481 2,080 0,041 0,518
3 0,376 2,657 0,006 0,524
Table 8: Mass participation factors - translatory movement in the y direction (first three vibration
modes)
Mode Per. (s)
Freq. (Hz)
Translatory mov. y
Uy ∑Uy
1 0,539 1,855 0,051 0,051
2 0,481 2,080 0,528 0,579
3 0,376 2,657 0,003 0,582
Table 9: Mass participation factors – rotation about the vertical axis (z) (first three vibration
modes)
Mode Per. (s)
Freq. (Hz)
Rotation about z
Rz ∑Rz
1 0,539 1,855 0,013 0,013
2 0,481 2,080 0,508 0,521
3 0,376 2,657 0,044 0,565
There should be considered a sufficient
number of modes that mobilize at least 90% of
the total mass of the building for the vibrations
modes. In this analysis, 12 modes were
considered, which resulted in a total mass
participation factor of 53% in the x direction,
58% in the y direction and 57% around the
vertical axis (z). Due to the fact that there are
two floors underground, the mass of the
building that actually participate in this analysis
is concentrated above the ground level, which
corresponds approximately to 22,56% of the
total mass. 90% of that percentage (20,30%)
result in the desired participation factor, which
is less than the values that were obtained.
Figure 7: 1st vibration mode – x direction
Figure 8: 2nd vibration mode – y direction
Figure 9: 3rd vibration mode – z rotation
According to the regulations, the behaviour
factor takes the value of 𝑞 = 2,029. Therefore
the spectral acceleration takes the value of
𝑆𝑑 𝑇 = 2,388 𝑚𝑠−2 for the type 1 seismic
9
action and 𝑆𝑑 𝑇 = 1,232 𝑚𝑠−2 for the type 2
seismic action. Due to its higher value, only the
type 1 seismic action has been considered in
this work.
Regarding the seismic structural elements,
primary and secondary elements were
considered in this work. Two models were
developed to design both kinds of elements.
The first (model 1) corresponds to the general
structure with no participation to the lateral
rigidity of the secondary seismic elements and
with a behaviour factor of 𝑞 = 2,029, and the
second model (model 2) considers the full
participation of all elements with a behaviour
factor of 𝑞 = 1,5 (that corresponds to the
minimum of 𝑞 value according to the
regulations). For the design of primary seismic
elements, the lateral rigidity of secondary
elements was taken as null (model 1). For the
design of secondary seismic elements,
stresses from model 2 were multiplied by
𝑑𝑒1 𝑑𝑒2 to take in account the increase of
stresses due to the increase of lateral
displacement of the model 1 (𝑑𝑒1) relatively to
lateral displacements of model 2 (𝑑𝑒2).
Secondary seismic elements were designed in
elastic phase and in ductility to compare both
situations in terms of rebar sections required.
For the elastic phase design, forces were
calculated from model 2 as indicated before,
affected by 𝑑𝑒1 𝑑𝑒2 and with 𝑞 = 1,5. For
ductile design, model 1 was used, with
𝑞 = 2,029. In the second situation the
secondary elements had to be detailed with the
recommendations of ductile elements, in order
to meet the same requirements concerning
ductility of primary seismic elements, as
indicated in the EC8-1.
The design and verification of safety of the
structural elements started from the results of
the three-dimensional finite elements program
SAP2000, for ULS.
For columns, compound bending has been
verified using the following simplified
expression presented in the regulations.
𝑀𝐸𝑑,𝑥
𝑀𝑅𝑑,𝑥
𝛼
+ 𝑀𝐸𝑑,𝑦
𝑀𝑅𝑑,𝑦
𝛼
≤ 1,0 6
The values of 𝛼 can be determined with the
following table.
Table 10: Recommended values for 𝜶
𝑵𝑬𝒅 𝑵𝑹𝒅 ≤ 0,1 0,7 1,0
𝜶 1,0 1,5 2,0
In the previous expression, resistant moments
in each direction were calculated considering
only the interaction between the axial force and
bending moment in that direction, not
considering the perpendicular moment.
Regarding the rest of the elements, the ULS
have been verified to guarantee the safety of
the structure.
The crack’s maximum opening has been
verified to be less than the limit of 𝑤𝑚𝑎𝑥 =
0,3 𝑚𝑚 in all structural elements.
Deformation in slabs have also been evaluated
to guarantee that the displacement in the
middle of the slab would be less than 𝐿 250 for
long term deformations and less than 𝐿 500
for the deformation that occurs after the
construction, for a diagonal span of 𝐿 =
8,12 + 8,12 = 11,46 𝑚. Cracking effect in
concrete, negative rebar and creep have been
considered to calculate long term
deformations.
10
Horizontal displacements due to seismic action
have also been verified to be less than the
limits set by the EC8-1 and to guarantee a
minimal spacing in the expansion joints of the
structure.
Once established a structural solution with a
three-dimensional static and dynamic analysis
realized, and considering safety criteria listed,
as well as calculation hypotheses to verify, the
building’s structural elements are designed.
The results of this design are presented in the
main document, such as reinforced concrete
drawings and global structure drawings.
8 - Final considerations
Should be noted that the beam-supported slab
has a better seismic behaviour than the flat
slab used in this work.
Should also be noted that the parametric
analysis made to determine the slabs
dimensions only considered vertical loads for
the fundamental combination of actions.
However, seismic actions have a considerable
influence in the design of those elements, so
the choice of this analysis in this situation
should be taken with caution.
Worth mentioning that the costs of materials
used in this work vary from country to country
and depends of the market situation. The
contractors’ technical capacities can also
influence the final costs of structural elements.
Should be noted that the use of partial
expansion joints the way they were installed in
this structure has its disadvantages. By using
expansion joints in every floor except in the
roof’s floor, bring high stresses to the
connecting elements in that area due to the
seismic actions. Nevertheless it is a good
option to reduce stresses in the inferior part of
vertical elements away from the centre of the
building.
This work has permitted to deepen the
knowledge acquired along the course of
Structural Engineering, and has also given the
opportunity to approach the experience to the
real life of a project engineer.
Key-words: structural design, seismic design,
mushroom slab or flat slab with drop panel, flat
slab, waffle slab, beam-supported slab,
punching shear, primary and secondary
seismic member.
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