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RAS BEIRUT TOWER Prezi
Transcript of RAS BEIRUT TOWER Prezi
RAS BEIRUT TOWER
Dr. Mahmoud EL-RABIH
Dr. Mahmoud EL-RABIH
Dr. Jamil DAMAJ
Dr. Yahiya DAOU
1-Introduction & Design Criteria
2-Predimensionement & Modeling
3-Seismic and Wind Analysis
4-Design of Slabs & Columns
5-Design of Shear Walls & Foundation
6-Design of Retaining wall, Stair, & Ramps
4 basements of 2.5 m height and of total area 3900 m2 used for parking and mechanical rooms
Ground & mezzanine floor of height 340 cm and 977 m2 surface area used for parking
14 typical floors are residential stories of surface area 520 m2 and story height 315 cm. This area is divided into two apartments 260 m2 each
Section & facade:
This project is 63.8m high above the sea level; The building surface area is 977m2, while the total surface areas is about 12000 m2. The height of this building is 54 m above the ground level and about 13 m below the ground level. This project contains 28 apartments, 260 m2 each and 8 stores 50-80 m2 each, & there is one main stair case at the middle of the building and two elevators in serve. The 4 basements have a capacity for 70 cars.
ACI-318-Building code requirements for structural concrete
UBC 97 – Uniform Building Code-1997
-Etabs: used to carry out the static and dynamic 3D modeling
-SAFE: used for designing solid slab, waffle slab and raft foundation
-WALLAP: used to design the shoring system
-S-concrete: used to design columns and shear walls
-BEAMD: used to predimensionment beams, stairs and basement walls
Live Load: 0.35 T/m2
Dead Loads: Tiles-0.2 T/m2
& partitions: 0.2 T/m2
Live Load: 0.2 T/m2
Dead Loads: Tiles-0.2 T/m2
& partitions: 0.2 T/m2
Seismic and Wind Loads:
Seismic zone: 2B
Importance Value: I=1
Site Class: Sc
Basic Wind Speed: 120 m/s
Exposure Category: B
1.2 D +1.6 L
0.9 D + 1.6 H
1.2 D + 1.6 L + 1.6 H
1.2 D + Ex/Ey
1.2 D + L + Ex/Ey
0.9 D + Ex/Ey
1.2 D + L + 1.3 Wx/Wy
1.2 D + 0.8 Wx/Wy
0.9 D + 1.3 Wx/Wy
1.2 D + L + Ex/Ey
0.9 D + 1.6 H + Ex/Ey
0.9 D + 1.6 H + 1.6 Wx/Wy
Solid Slabs & Ribbed slabs.
Reinforced concrete Shear Wall
Reinforced concrete Retaining Walls
Columns of Reinforced Concrete
Basements, Ground floor and 1st floor
These floors are set to be Solid Slabs of thickness 35cm
The thickness was choosed to control deflection criteria, Punching criteria, and flexion criteria in accordance with ACI code.
2nd to 14th typical floors
The typical floors are set to be ribbed slab of thickness 32cm
The slab thickness choosed to control deflection according to ACI code chapter 9- table 9.5a.
φPn,max = 0.80φ [0.85fc (Ag – Ast) + fyAst ]
Beams were dimensioned using BEAMD
The columns dimensions given by architecture were verified if they are valid according to this equation:
A mathematical model of the structure is constructed for the purpose of determining member forces and structure displacements resulting from applied loads and any imposed displacements
Modifier Factors for Stiffness
The ACI code recommends stiffness modifiers that are primarily used to take into account cracking and inelastic action that occurred along each concrete element
Walls -uncracked ......................0.7Ig
Flat slabs .....................................0.25Ig
Basis for Design
seismic zoning 2B - Z =0.2,
Soil characteristics = Sc,
Occupancy category = 4,
Seismic response coefficients:
Ca = 0.24, Cv = 0.32
Structural system: Bearing wall system,
R = 4.5
In accordance to UBC code:
Static Force Procedure: The total design base shear in a given direction shall be determined from the following formula:
V = Cv.I.W/(R.T) = 610 T
W = 13285 T
T = 1.5 sec
Design Base Shear
Story Drift Due to Lateral Load
Story drifts shall be computed using the maximum inelastic response displacement :
ΔM = 0.7 R x ΔS ≤ 0.02 x story height
According to UBC code
The maximum Lateral Displacement < story height/250
Basic Wind Speed = 120 Km/h
Exposure Category : B
Design Wind Pressure:
P = Ce Cq qs Iw = 0.76 KN/m2
Lateral Drift Due to Wind Pressure
Story drift is recommended not to exceed 1/350 of story height.
- Maximum displacement under wind load is limited to 1/500 of Building height.
• Slab thickness = 35cm
• Punching shear is checked using “SAFE”
• One way shear is also checked such that Vu < 0.5 φVc
• Deflection is checked at the long term: (Δlong) + (Δi) l = 2.1cm < L/240.
• Steel Reinforcement due to bending moment: T12@20cm top & bottom mesh in both directions, with additional steel T14@20cm on the top of columns in both directions.
The slabs were already present in the Etabs Model with all their loads and combinations and materials specifications. Then the slabs were imported with all their data from Etabs to SAFE and then run analysis using finite element method
Safe model of Basements Solid Slab
• Slab thickness = 32cm
• shear is also checked such that Vu < φ(Vc + Vs)
• Deflection is checked at the long term: (ΔLong) + (Δi) l = 2.1cm < L/240.
• Ribs 20cm thick, reinforced by: 2T12 in Top and Bottom unless specified in drawings.
• Steel Reinforcement for top slab 8 cm is: T10@20cm top mesh in both directions
Ribbed slab, 1st – 14th floor
Safe Model of Ribbed Slab
Beams were designed using safe that gives the Bending Moment Diagram & the needed reinforcement, and here is an example of Beam 4:
Design of Columns
column is a vertical structural member supporting axial compressive loads
Ex: Column C6 that was designed by the aids of S-Concrete software
S-concrete result of C6
The term shear wall is used to describe a wall that resists lateral wind or earthquake loads acting parallel to the plane of the wall in addition to the gravity loads from the floors and roof adjacent to the wall. Such walls are referred to as structural walls in ACI Code Chapter 21
Ex: W4 by Using SConcrete Software
After inserting the section properties and load cases, the S-concrete shows acceptance of W4 of this section:
Types of Raft Foundation:
• Classical rigid model assumes uniform contact pressure under a raft when its center of gravity coincides with the center of gravity of loads, that settle uniformly under a load.The rigid analysis gives relatively much bigger section.
• Modern flexible models use the theory of soil interaction, depending on the rigidity of the raft. In flexible raft, there will be more settlement under the loads, so pressures will be varying under the foundation.
a) Reinforcement: 5T20/ml mesh top and bottom in both directions with an additional steel 7T16/ml for columns.
b) Punching shear: The punching shear is checked in all rafts, all ratios are smaller than 1.
c) Maximum displacement: 3.52cm<5cm settlement.
d) Max soil pressure under service loads=3.05Kg/m2 < 4Kg/m2 ultimate bearing capacity
e) The crack width <0.15 mm
Safe Output Data
Concrete basement walls are designed to support two main types of loads. First, the vertical loads coming from the vertical structural elements and slabs lying on it. Second, the lateral loads originated either from earth pressure or from the hydrostatic pressure of water
Friction angle Φ = 30
Specific weight γ=2 T / m3
Cohesion C = 0
Then K0 = 1 – sin Φ = 1 - 0.5 = 0.5
Qsoil= K0 x ρ x ht = 12.5T / ml
Quniform = K0 x s x 1 = 0.5 T / ml
The wall is considered as a beam which is fixed in the raft foundation and simply supported on the basement floors. Using BEAMD we calculate the moment and checked for shear forces on this wall
The ramp was subjected to impact live load 2T/m2 and a dead load of 0.2T/m2 and its self weight, its considered as beam 1m width and simply supported on walls. It was designed using BEAMD and checked for shear capacity.
The simplest form of reinforced concrete stairway consists of an inclined slab supported at the ends upon beams, with steps formed upon its upper surface. Such a stair slab is usually designed as a simple slab with a span equal to the horizontal distance between supports. This method of design requires steel to be placed only in the direction of the slab length.
The final reinforcement was as follow:
Bot T14@20 & Top T12 @20.
7- Shoring System
In order to reach the underground level 13.2m we have to consider piles to support temporary the soil. The shoring system was designed using WALLAP
- Bulk density:19 KN/m3
- Young modulus: 75000
- K0 : 0.625, Ka : 0.455, KP : 2.198
- Cohesion (C) : 40KN/m2
- Surcharge : 1 T/m2
The piles were designed by S-concrete as a column carrying lateral loads
The piles are of diameter 80 cm reinforced by 12T20 and spiral T14@15
- Maximum displacement at the free head 8mm < 20 mm
- Maximum displacement at the level of anchor = 14mm < 35mm
- Bond length 5.5 - 6 m
THANKS FOR YOUR ATTENTION
The specified compressive strength of concrete is equal to 350 Kg / cm2 for the columns, walls and raft. And fc’ = 300 Kg / cm2 for other elements.
Yield strength of steel reinforcement = 420MPa
Unit weight: W = 2.5 t/m3
Various types of aggregate undergo chemical reactions in concrete, leading to damaging expansive phenomena. The most common are those containing reactive silica, that can react (in the presence of water) with the alkalis in concrete
Corrosion of reinforcement bars
The expansion of the corrosion products (iron oxides) of carbon steel reinforcement structures may induce mechanical stress that can cause the formation of cracks and disrupt the concrete structure.
Carbonation of concrete is a slow and continuous process progressing from the outer surface inward, but slows down with increasing diffusion depth. Carbonation has two effects: it increases mechanical strength of concrete, but it also decreases alkalinity, which is essential for corrosion prevention of the reinforcement steel
Chlorides, particularly calcium chloride, have been used to shorten the setting time of concrete. However, calcium chloride cause chemical changes in Portland cement, leading to loss of strength, as well as attacking the steel reinforcement
Sulfates in solution in contact with concrete can cause chemical changes to the cement, which can cause significant micro structural effects leading to the weakening of the cement binder
When water flows through cracks present in concrete,water may dissolve various minerals present in the hardened cement paste or in the aggregates, if the solution is unsaturated with respect to them. Dissolved ions, such as calcium (Ca2+), are leached out and transported in solution some distance.
Distilled water can wash out calcium content in concrete, leaving the concrete in brittle condition.
Up to about 300 °C, the concrete undergoes normal thermal expansion. Above that temperature, shrinkage occurs due to water loss; however, the aggregate continues expanding, which causes internal stresses. Up to about 500 °C, the major structural changes are carbonation and coarsening of pores. At 573 °C, quartz undergoes rapid expansion due to phase transition, and at 900 °C calcite starts shrinking due to decomposition
Due to its low thermal conductivity, a layer of concrete is frequently used for fireproofing of steel structures. However, concrete itself may be damaged by fire