0-14 Loading Systems Report

0-14 Loading Systems ReportAim and Objectives:
The report would show the importance and short comings of different loading systems in relation to the plan of the building O-14.
Introduction:
A load bearing wall gives a building structural integrity. It carries and distributes weight from the roof and top floors down to the foundation. Damage to a load bearing wall can cause floors to sag, finishes to crack and the entire structure to collapse. The external walls of your house are almost always load-bearing, supporting the majority of the roof weight and transmitting the load to the foundations. The internal walls of your house are not so easy to categorise. At least some of the walls will be load-bearing (except in some timber frame houses, etc) but some will also be non load-bearing.

O-14 PLAN:
With O-14, the tower typology has been turned inside out – structure and skin have flipped to offer a new economy of tectonics and of space. The concrete shell of O-14 provides an efficient structural exoskeleton that frees the core from the burden of lateral forces and creates highly efficient, column-free open spaces in the building’s interior. The exoskeleton of O-14 becomes the primary vertical and lateral structure for the building, allowing the column-free office slabs to span between it and the minimal core. By moving the lateral bracing for the building to the perimeter, the core, which is traditionally enlarged to receive lateral loading in most curtain wall office towers, can be minimized for only vertical loading, utilities, and transportation. Additionally, the typical curtain-wall tower configuration results in floor plates that must be thickened to carry lateral loads to the core, yet in O-14 these can be minimized to only respond to span and vibration. The shell is organized as a diagrid, the efficiency of which is married to a system of continuous variation of openings, always maintaining a minimum structural member, adding material locally where necessary and taking away where possible. This efficiency and modulation enables the shell to create a wide range of atmospheric and visual effects in the structure without changing the basic structural form, allowing for systematic analysis and construction. As a result, the pattern design is a combination of a capillary branching field, gradients of vertical articulation, opacity, environmental effects, a structural field, and a turbulence field.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Discussions and analysis:
Making the exoskeleton of O-14 its structural base has so many significant advantages but however it’s not the only way with which we can go about it. There are different loading systems that can be used to achieve the same goals at the same time still maintaining the architectural and structural integrity of the building, some of which would be highlighted below.

Rigid frame system:
A rigid frame in structural engineering is the load-resisting skeleton constructed with straight or curved members interconnected by mostly rigid connections which resist movements induced at the joints of the members. Its member can take bending moment, shear and axial loads. In this system each and every member must help in the transfer of lateral loads to the foundations through rigid connections. These systems are usually very regular and not of great height. The strength of the system depends upon the integrity of each of the elements working together as one. The down side is, once an individual member fails there is most likely going to be a structural failure.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Discussions and analysis:
With the design given and using the rigid frame loading system the columns and beams are arranged as follows
Columns: first a row of columns were places all around the existing core wall with eight larger ones placed two each on either side of the building
Beams: The beams just run along the span of the column placement. There are also four hidden beams which provide support for the floors at the extended corners of the building

Advantages of rigid frame system to O-14
* There are little or no advances to this system with respect to the building as it produces more challenges than being a viable alternative.

Disadvantages of rigid frame system to O-14
* Irregular shape:-The irregular shape of the structure becomes a major challenge when it come s to the placement of columns and beams. In most conventional rigid frame structures (which are generally rectangular in nature) it is easy to place columns and beams while accounting for span and load distribution. This problem can be solved by increasing the size of the columns and beams but that also in itself has some limitations.

* Open floor system:-the fact that the building is an office complex with an open floor design provides another major challenge for this system. With an open floor design there are very few walls that can act as supports (shear walls). More share wall can be incorporated into the structure but that would greatly change the orientation of the building and also affect the architectural design.

* Complication with flooring:-the flooring system provided a little bit of a challenge due to the irregular shape and the rigid frame system being used, a combination of joist and flat slab systems was chosen as it would be the most cost effective solution. However waffle slabs can be used as a better alternative.
In conclusion a rigid frame design is a brilliant concept but however with this structure and its design a rigid frame would just not work.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Hinged frames with bracings

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Discussions and analysis
In this system the hinged frames with cross bracings are placed all around the structure with exception to the corners, here a grid style bracing parallel to the next bracing is used.
The bracings are placed on the glass façade of the building rather than on the external one, this means even thou the structural system has changed the architectural system does not have to change much, a waffle slab is chosen for the flooring system due to the large open space within the structure.

Advantages
* Little change to the existing design, as mentioned above this architectural design does not change because of the placement of the frame

* Cost effective:-this alternative design would be more cost effective seeing as the exoskeleton of the building(one of the major component of the existing design) is no longer carrying the weight of the structure now it can be scaled down with less reinforcement or even changed to use a different material totally like wall tile or some other façade.

* Change in materials:-o-14 designers used reinforced concrete as the core material for the construction of the building, however with change in system it is possible to use steel which is cheaper and also the change in material goes well with the open concept design of the building


Disadvantages
* Difficulties with combining floor and steel frame:- it is difficult to provide connections between steel and concrete to transfer the large forces generated. The large floor slab could create a potential problem when it comes to transferring the load.
* diagonal members with fire proofing can take up considerable space, some of the member could get too big thereby ruining the space and the internal aesthetics

In conclusion even though this system has its draw backs, it is one of the more viable alternatives.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Rigid frame with shear wall
Reinforced concrete shear walls and cores act in a similar way to lattice frame bracing.
Shear walls are normally constructed in in-situ reinforced concrete, but may be either pre-cast concrete of brickwork. They are more rigid than other forms of bracing, and there is a need for fewer of them. Shear cores are shear walls in boxform which provide torsional or twisting resistance as well as providing a highly effective bracing system.
Shear walls are effective especially when combined with columns and beams, a structure capable of withstanding multiple forms of loading is formed.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Discussions and analysis:
In this system a combination of columns, beams, internal shear wall (core wall) and external shear walls. The columns and beams run along the span of the building parallel to each other on each side of the core wall, incorporating shear walls and rigid frames provides the kind of structural support which was not possible with just the rigid frame alone. The external shear wall at the four corners of the building act as both load bearing wall and shear wall which also help to improve stability
Advantages
* the structure is able to withstand any kind of loading(torsion, lateral, axial),with both the internal and external shear wall a coupled with the column it is by far the safest design possible
* reduced construction cost:-only part of the external shear wall is being used as a structural component so therefore the part no being used can be either changed to a cheaper material or just left open
* it allows for any type of flooring system:-any type of flooring system can be used with this design allowing for greater amount of flexibility in that respect

* With the columns outside and also the external shear wall the problems with the rigid frame alone system have been addressed, especially seeing as the irregular corners have been used to the advantage of the building.

* concrete walls tend to be thinner than other bracing systems and hence save space in congested areas such as service and lift cores, this means with the internal core wall can be constructed a lot thinner than the initial design
Disadvantages
* Opposite to the rigid frame alone system there are very little disadvantages to the system
In conclusion this system is the best alternative to the existing system in place

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Super frame tubular design:
In structural engineering, the tube is the name given to the systems where in order to resist lateral loads (wind, seismic, etc.) a building is designed to act like a three-dimensional hollow tube, cantilevered perpendicular to the ground. In the simplest form of the tubular design, the perimeter of the exterior consists of closely spaced columns that are tied together with deep spandrel beams through moment connections. This assembly of columns and beams forms a rigid frame that amounts to a dense and strong structural wall along the exterior of the building.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Discussions and analysis:
Conventionally the columns in a tubular structure are arranged in on the outside of the structure,however here the opposite is the case,the columns are arrange on the inside of the structure with cantilever beams on top of them to carry the floor.the columns line the outside of the interior shaft(opening) of the building.
Advantages
* Little change to the existing design, architectural design does not change because of the placement of the columns
* The floor is easily supported by the columns without any external supported needed so therefore there is no need for the exoskeleton o the building

* Cost effective:-this alternative design would be more cost effective seeing as the exoskeleton of the building(one of the major component of the existing design) is no longer carrying the weight of the structure now it can be scaled down with less reinforcement or even changed to use a different material totally like wall tile or some other façade

* Open floor system:-the fact that the building is an office complex with an open floor design provides another major challenge for this system. With an open floor design there are very few walls that can act as supports (shear walls). More share wall can be incorporated into the structure but that would greatly change the orientation of the building and also affect the architectural design

* The columns act both as shear wall and rigid frame so lateral and axial forces would not be a problem

Disadvantages
* Lots of columns needed to carry the floor slab,seeing as the floor beams willl cantilever.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
WIND LOADS
Buildings and their components are to be designed to withstand the code-specified wind loads. Calculating wind loads is important in design of the wind force-resisting system, including structural members, components, and cladding, against shear, sliding, overturning, and uplift actions.

h(m) | Vb | Ce(z) | qp |
10 | 4.5 | 1.2 | 15.1875 |
20 | 4.5 | 1.6 | 20.25 |
30 | 4.5 | 1.9 | 24.04688 |
40 | 4.5 | 2.2 | 27.84375 |
50 | 4.5 | 2.35 | 29.74219 |
60 | 4.5 | 2.5 | 31.64063 |
70 | 4.5 | 2.6 | 32.90625 |
80 | 4.5 | 2.75 | 34.80469 |
90 | 4.5 | 2.85 | 36.07031 |


Table 1

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |

E | A(e/5) | B(4/5 e) | We(A) | We(B) |
35 | -1.2 | -0.8 | -182.25 | -121.5 |
35 | -1.2 | -0.8 | -486 | -324 |
35 | -1.2 | -0.8 | -865.688 | -577.125 |
35 | -1.2 | -0.8 | -1336.5 | -891 |
35 | -1.2 | -0.8 | -1784.53 | -1189.69 |
35 | -1.2 | -0.8 | -2278.13 | -1518.75 |
35 | -1.2 | -0.8 | -2764.13 | -1842.75 |
35 | -1.2 | -0.8 | -3341.25 | -2227.5 |
35 | -1.2 | -0.8 | -3895.59 | -2597.06 |

Table 2

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |

Force at 90m

Force between 60 and 80m

Force between 40 and 60 m

Force between 20 and 40m

Force between 0 and 20 m

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |

Seismic loading

Step 1
T=Ct * H0.75

T=0.075 * 900.75
T=2.19 sec
Step 2
S=1.35 TB(S) =0.20 TC(S) =0.8 TD(S) =2.0
VS , 30(m/s) < 180 NSPT < 15 CU(kpa) < 70

ag = 0.06 * g(9.81) = 0.5886 m/s2
η= 1
Step 3
Se = ag * s *[1+TTB(η*2.5-1)]
=0.5886 * 1.35[1+10.95(1*2.5-1)]
Se = 13.84
TB ≤ T ≤ TD Se (T) = ag * s * η * 2.5 =1.98
I =1.2
Sd(t)=1.98 * 1.2 =2.376

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Dead Load= 2.2 KN/m2
Live Load = 0.7 KN/m2
Dead Load + O.4*LIVE LOAD
=2.2+0.4*0.7
=2.48 KN/m2
Floor Area= 557 m2 Number of floor= 22
Total floor area = 557* 22 = 12254 m2
Weight=12254*2.48
=30389.92 KN
Mass = 3097.8 kg
Sd =2.376 η=1 Mass= 3097.8 Kg
Fb =2.376 * 9.81 * 1 * 3097.81
=72205.5 KN
qo =3.0 *1.2 =3.6
Fbm= Fb / 3.6
= 72205.5/3.6
= 20057.08 KN
Equivalent base shear of structure =20057.08 KN

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
h(m) | w(KN) | W*h | Fbm(KN) | f(KN) |
4 | 1381.36 | 5525.44 | 20057.08 | 79.277 |
8 | 1381.36 | 11050.88 | 20057.08 | 158.554 |
12 | 1381.36 | 16576.32 | 20057.08 | 237.831 |
16 | 1381.36 | 22101.76 | 20057.08 | 317.108 |
20 | 1381.36 | 27627.2 | 20057.08 | 396.385 |
24 | 1381.36 | 33152.64 | 20057.08 | 475.662 |
28 | 1381.36 | 38678.08 | 20057.08 | 554.939 |
32 | 1381.36 | 44203.52 | 20057.08 | 634.216 |
36 | 1381.36 | 49728.96 | 20057.08 | 713.493 |
40 | 1381.36 | 55254.4 | 20057.08 | 792.77 |
44 | 1381.36 | 60779.84 | 20057.08 | 872.047 |
48 | 1381.36 | 66305.28 | 20057.08 | 951.324 |
52 | 1381.36 | 71830.72 | 20057.08 | 1030.601 |
56 | 1381.36 | 77356.16 | 20057.08 | 1109.878 |
60 | 1381.36 | 82881.6 | 20057.08 | 1189.155 |
64 | 1381.36 | 88407.04 | 20057.08 | 1268.432 |
68 | 1381.36 | 93932.48 | 20057.08 | 1347.709 |
72 | 1381.36 | 99457.92 | 20057.08 | 1426.986 |
76 | 1381.36 | 104983.4 | 20057.08 | 1506.263 |
80 | 1381.36 | 110508.8 | 20057.08 | 1585.54 |
84 | 1381.36 | 116034.2 | 20057.08 | 1664.817 |
88 | 1381.36 | 121559.7 | 20057.08 | 1744.094 |
Total | | 1397936 | | 20057.08 |

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Introduction
For this project we had to come out with a new design for the existing O-14 Tower present in Business Bay, Dubai. Due to the fact that the most distinguishing part of the structure is the facade around it, we chose not to change the looks of the structure too greatly. Another factor which came into the designing process was that the facade around the building actually was the main support for the building and so we decided to only focus on that part of the structure. A side view of our new structure can be seen to the right in Figure 1. A top view of a structure can be seen below in Figure 2. Our proposed structure will be discussed in the next paragraph.
Figure 2: Modified Structure (Top View)
Figure 1: Modified Structure


NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Modifications
Figure 4: Original Reinforcement
Figure 3: Foam Concrete: Reinforcement
Firstly as can be seen in Figure 1 there are no holes, this is because we were not able to put holes on a curved structure in the design program which we chose to use. There will still be holes in the structure but they will be a little smaller than they were before. The main change in the design of the facade would be the replacement of some of the concrete to reinforced foam concrete. If one takes a look at Figure 2, one is able to see the red areas which are marked out in the reinforcement. Firstly the shear walls which are in place in the middle of the structure will remain in the same place as they were originally but the outer facade will be changed. In Figure 2, the red part of the facade which is marked out will remain concrete and the amount of concrete which is present in the facade will increase as one moves further down the structure. As one can see there is a triangular shape which has been marked out in Figure 1, in this area all of the concrete will be replaced with foam concrete. In Figure 2 a top view of the structure can be seen, with the white areas in the facade being changed to foam concrete. We decided to make this change because it would make the building lighter and thus there would be less weight for the facade to have to hold up. When designing the way that the foam concrete would be connected to the rest of the structure I designed Figure 3 which can be seen below. In this image the reinforcement does not seem to continue into the structure but in reality it would continue just as in Figure 4. Figure 4 which can also be seen below is the original reinforcement pattern which the structure followed. If one compares Figure3 to Figure 4, then one can deduce that the layout would be pretty much the same. The reinforcement would continue from the concrete through to the foam concrete. This idea combined with the amount of loading that the structure had to bear posed the next problem. This problem was that we could not use ordinary grade foam concrete. For this project we would have to use high grade foam concrete with a high bearing capacity. When researching online we came across a type of foam concrete called D1200 which has a bearing capacity of approximately 17kN which when compared to concrete of bearing capacity 34kN would seem to satisfy the job. This would change the original Stress Grid which can be seen in Figure 5. In this grid the levels of pressure which are present in the structure are illustrated with different colours. As colours tend to red the intensity of the stresses on the structure increases. The new Stress Grid for the structure would not have a Stress Grid with the same amount of red. This would be due to the fact that the wind pressure is lower on the structure because the structure weighs less and secondly due to the fact that the structure itself weighs less. The original facade weighed approximately 33.218MN, while the modified structure weighs approximately 30.077MN. This is an approximate 1/11 drop in weight which will reduce the amount of weight acting on the lower sections of the structure.

Figure 5: Stress Grid

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |

Wind loading for new design

334.13N
121.5N
592.31N
878.85N
1174.5N
1518.75N
1849.84N
2227.5N
2587.95N

2966.625N



* Face – 34.012MN
* Back – (-34.612MN)

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Seismic loading
* Original structures fb =72205.5 KN

* New design’s fb = 71465.21 KN

* Equivalent base shear(fbm) of original structure =20057.08 KN

* New design’s equivalent base shear(fbm) = 19851.4KN

Advantages of the new design
* The total weight would be lower- the original structure is basically made out of reinforced concrete (mix of steel rebars and concrete), with the new design reinforced concrete would only make up the stress areas of then structure while the other parts would be filled with foam concrete. Therefore due to the lower weight of foam concrete the new design would cut down the total weight of the structure
Total weight of existing structure=33218.401KN
Weight of new design (foam concrete +normal concrete) =30077.346 KN

* Good fire resistance-foam concrete has a higher thermal conductivity than normal concrete even though both forms of concrete are not flammable. Foam concrete react to extremely high temperatures better than normal concrete.

* Cheaper construction costs-Due to the fact that no visible changes were made, we are only able to discuss the advantages which the structure would obtain if foam concrete was to be used. If this new design were to be built the cost of construction would be cheaper. This is due to the fact that foam concrete is both cheaper to make and lighter than normal concrete. The fact that it is cheaper to make also allows for the foam concrete to transport to and around site much easier than typical concrete. These advantages can be achieved and still the original design can be kept. The advantage of the original design being kept would be that the structure would aid with the cooling of the building. This is because the hot air which builds up between the facade and the structure would rise and the cooler air would remain.

NAME ADAMOH HUSNI OLAYEMI | | | | |
TITLE LOADING SYSTEMS | | | | |
LECTURER DR AMIN GHAFOORIPOUR | | | | | |
DATE 18TH April 2012 | | | | |
Disadvantages of new design
* Possible fracture point-if not properly done, the point at which the foam concrete and normal concrete meet could be a fracture point that is it could be a weak point in the structure. A way to solve such a problem would be incorporating extra reinforcement at those points.
* Possible deviation from original aesthetic features- using foam concrete mean there would be less hole in the structure, see as the hole account for the architectural/aesthetic feature of the structure.

Conclusion
There are many way with which the design of the structure could be changed and improved, it would come down to preference and most efficient solution to get the best design possible.

0-14 Loading Systems Report 9.2 of 10 on the basis of 887 Review.