CE4670 CASE STUDIES GROUP 7 CE18B024- ROHIT B CE19B009-G SARAYU CE19B056-JURAIJ CE19B065-MANIKANDAN CE19B107-GURUCHARAN TABLE OF CONTENTS Introduction, Architecture and Geography Construction Plan Foundation Super Structure Observatory Deck, Pinnacle Wind Modelling and Seismic Structural health monitoring Comparison with other structures GENERAL DETAILS Jeddah Tower previously known as Kingdom Tower, is a skyscraper construction project currently on hold. Located on the north side of Jeddah, Saudi Arabia, Architecture Style: Neo Futurism Architecture: Adrian Smith+Gordon Gill Architecture Structural Engineering : Thornton Thomasetti,Magnussen Klemenicic Associate Developer: Jeddah Economic City Construction Contractor: Saudi BinLadin Group Estimated Budget : 1.23 Billion USD Construction Started: 1 April 2013 HOW HIGH CAN WE CONSTRUCT? SKY SCRAPPER WITHOUT COLUMN This tower is going to be the first tower to reach 1 Km milestone This tower is constructed to enhance the tourism industry in Saudi Arabia. As a state of an art project of Jeddah Economic City To be more slender, stiffer, and taller it is constructed using Reinforced Concrete After construction, it will be the world's tallest building Introduction It's shape is inspired by a bundle of leaves shooting up from the ground and it has been designed on Y shaped plan . its structure is reinforced concrete frame almost entirely made of reinforced concrete shear walls,coupling beams & reinforced concrete slabs Geography Tower is located in coastal plain of red sea . Due to coastal influence there will be salt content in the wind , need to consider rust resistance region is deserted area with sandy soil -relatively low strength. soil is silty sand type in desert , pile foundation and raft are used . Geography and environment condition need to design in a way in which wind forces are less. jeddah is lying on tropic of cancer usually have high temperature on day throughout year In winter temperature will reduce 10 C . while construction needs proper control of temperature to reduce shrinkage and cracks . also need to consider expansion of concrete due to high temperature . Architecture The Tower has a tapered Y shape at the base with an angle 120 degrees extending 12 hectares with three wings terminating at different heights . The tower is continuously Tapering as the tower ascends to the top, And the tower has an aspect ratio of 12:1, which is the highest for any man-made structure in the world. Architecture The architectural style for the tower is Neo Futurism, which is to make unconventional building shapes, prioritizing modern aesthetics. It aims to have a more continuous surface. It promotes the use of new materials like glass, aluminum, and steel to make the structure look more slender, and the reflecting ability of the building is also considered for the design. Architecture Another major attraction of the structure is the observatory desk, Once completed it will be the deck located at the highest elevation in the World Which is at level 157 at an elevation of 630 meters, apart from the large sky desk, small terrace connecting two wings are provided to increase the terrace area, also to help cleaning the external surface. Architecture Figure shows the usage of different parts of the tower in which the majority of the part is residential the Bottom part is reserved for the hotel and office to maximize the floor area for it, and Executive suites and penthouses are reserved for the business class and the royal family. Height of each floor level is only 4 m Construction Reached at 260 m height and 45% concrete is placed until now Design ideology is to use concrete till maximum height possible, for this purpose special concrete boom pump is used Tower Jump formwork is used for the construction First the walls are constructed then the slabs are constructed later To avoid differential heating in the concrete soon after placing insulation is provided To control heat developement due to concrete placing, and to prevent evaporation frozen ice water is used in concrete mix FOUNDATION DESIGN 1008 m tall reinforced concrete structure No individual columns Load bearing wall-slab system Varying loads: 50 MN for centre walls 400 MN for wing end walls FOUNDATION DESIGN Raft foundation chosen : Poor soil conditions Even load distribution Area = 3720 m2 Depth: 4.75 m average Gravity load: Superstructure: 8428 MN Raft: 416 MN Total: 8844 MN FOUNDATION DESIGN Subgrade pressure below raft = 8844 MN/3720 m2 = 2.38 MPa GEOLOGIC SETTING Project along Red Sea coastal plain Aeolian sand deposits on surface Underlain by coraline limestone Pockets of clay or silty sand Shells, salts and gypsum deposits SUBSURFACE CONDITIONS Project at underdevoloped location Seven Borings(3x120m, 3x150 m, 1x200m) In-situ tests: Groundwater observation wells Pressuremetre tests P-S suspension logging(Wave velocity) Groundwater level on par with Red Sea. SUBSURFACE CONDITIONS Laboratory tests for rock: Density Water content Point load test Unconfined compressive strength CD Triaxial test Repetitive Triaxial tests OBSERVATIONS OBSERVATIONS INFERENCE 45 metre deep Coralline Limestone Porous, 1.8 specific gravity 1.5-2.5 MPa UCS, too close to 2.38 MPa So Raft soundation alone not sufficient Bored Pile-Raft Foundation chosen Angular gravel layer can affect pile stability FULL SCALE PILE LOAD TEST Load tests for following configurations: Bored pile(Circular) Barrette pile (Rectangular) 1.5 m square footing Bentonite slurry and polymer stabilisers Measured: Unit skin friction Load-settlement behavior OBSERVATIONS OBSERVATIONS OBSERVATIONS INFERENCE Test data gives: Allowable bearing capacity Modulus of deformation Poor result: Mineral slurry Barrette pile Most suitable: Circular bored pile Natural slurry for shallow foundation Polymer slurry for deep foundation FINITE ELEMENT ANALYSIS Six distinct layers Grouped by Engineering properties Stiffness data from: Lab tests P-S logging test Full-scale load test Upper and lower limits for response/stiffness ASSUMPTIONS OF FEM MODEL 270 bored piles in Raft-pile foundation Raft modeled as solid tetrahedral elements Elastic modulus of each element = 36.7 MPa Mohr-Coulomb model for Coralline layer Elastic model for other layers Horizontal stratification assumed Beam elements to model pile behavior Negligible tip bearing capacity ASSUMPTIONS OF FEM MODEL Sta Piles upto 45 m depth dug with natural slurry Remainder with polymer slurry 300x300x200 m box model Loads as pressure tips on top of Raft. Stages of subsurface settlement: 1) Self weight 2) Due to pile+raft 3) Due to superstructure Iterative procedure between structural and subsurface model INITIAL DESIGN Assuming equal pile depths, Load carried by each pile = 8844/270 = 33 MN 45 m piles found suitable Center to edge differential settlement = 173 - 108 = 65 mm But further iterations show higher loads on foundation wings 1:900 angular rotation FINAL DESIGN Pile dimensions: 226x1.5 m piles 44x1.8 m piles Varying pile depth: 45 m at wings 105 m at center Natural slurry piles avoid gravel zone INITIAL SETTLEMENT ESTIMATE CONVERGED ESTIMATE PILE HEAD AXIAL LOAD ESTIMATE FINAL DESIGN Center pile 5 m above sandstone layer Differential settlement = 108 - 86 = 22 mm Significantly below initial design (65 mm) 1:2000 angular rotation Better load distribution BEARING PRESSURE ON ROCK Maximum pressure = 625 Kpa Below raft wings and center of raft UCS of corraline rock = 1.5 MPa atleast Factor of safety = 1500/625 = 2.4 LOAD SHARING Pile head loads: 1.5 m pile: 18 ~ 29 MN 1.8 m pile: 24 ~ 38 MN 75% superstructure load taken by piles 25% by rock subgrade below raft Super Structure There are no columns in the tower! This tower has a bearing wall system Shear wall is the only vertical load transfer element, Which is continuous from foundation to top without joints. There are no outriggers to transfer lateral load from exterior to core. The loads are carried to the foundation directly, because the structure stiff on all part of structure. There are no spandrel beams in the tower Super Structure To connect shear walls Coupling beams are provided. Slabs are supported on the load bearing wall Super Structure Why shear walls and no Columns? Shear walls are stiffer than the columns since the selfweight is more than the columns Shear wall can bear lateral loads better than the columns can only transfer compression loads mainly. Using shear wall will make the structure more efficient in size as compared to the group of columns that can bear same load Make structure more slender As a disadvantage shear wall reduce the effective usage space And have lower axial load capacity than column Super Structure Load Bearing wall Inner Triangular core walls These Triangular Inner core provides High Torsional Stiffness to the tower Wall is nearly solid and have only very few openings This wall extend from the foundation to the top Lift systems are provided in the central region These walls are 800mm thick at the base Super Structure Load Bearing wall Corridor walls These walls are the second most highly stressed due to the openings in the walls At the openings, these walls are connected using 1.6 m deep single span coupling beams These openings are considered as critical locations in the design These walls are 1m thick at the base Super Structure Load Bearing wall Transverse fin walls These walls are the highly stressed part of the tower. There are no openings in the wall,but the length is less Two fin walls on opposite sides of the stair walls are connected by three span coupling beam These walls are 1.2 m thick at the base Super Structure Load Bearing wall Wing End walls These walls are the stabilizers to the tower against lateral loads These are highly stiff element, Very few openings, since shear wall have extra thickness to provide fire resistance to emergency stair ways These are the walls at end of the wings of tower These walls drops off as the tower taper These walls are 850 mm thick at the base These walls are connected to corridor walls by 1.5 m thick coupling beam at base Super Structure Coupling Beams Coupling beams are provided to connect between the shear walls inorder to distributer loads within system. Coupling beam will increase lateral load bearing capacity. Decrease overturning effect and increase overall Stiffness of the tower Materials used High Strength Self Consolidating Concrete is used for construction For Rebaring due to heavy reinforcement steel plates are used Due to late strength developement of High Strength Concrete Tested strength is higher than planned End walls sloping geometry The three walls rise at a constant incline. Three slightly different anngles for each of them. Different elevations and distinctive top of the tower. Tower + Spire Aspect ratio : 12:1 But how do we measure it? The top views of the tower bearing wall and that of the upper 1/3rd of the tower are not same End walls come closer and closer and forms the walls of the spire. Top 50m of the tower- concrete silo No transfer of the load. This graph explains axial load stress behaviour versus time We can get any behavioural and strength related topic through this graph. Observatory deck Jeddah Tower will have the highest observatory deck and hanging balcony, about 652 meters above the sea level. Core of the project The deck occupying 500 sq.ft has a bird's eye view of the Red sea This oservatory deck can be assumed as a cantilever structure. Skyraft Its provided above which the closed silo is constructed It has a thickness of 4 meter Facade The smooth, tilted façade of Jeddah Tower generates a helpful effect known as wind vortex shedding When wind coils around the edge of a building, rushing in to enter the low-pressure area, vortices form, causing the structure to wobble from side to side due to velocity and pressure changes. The facade features low conductivity glass to beat Jeddah’s high temperatures. World’s largest LED screen to be integrated into this facade. Seismic Modelling Tower is constructed in Low Moderate Earthquake Prone area in Saudi Arabia It is conservative according to Saudi Building Code (SBC301) This tower belong to site class B acccording to code They have Conducted site Specific Hazard Analysis Wind is considered as more critical than earthquake for the design of the tower Due to presence of shear wall it imrove the stiffness and the mass. Wind Modelling 50 Year return wind speed for 3 sec is considered as 42.2 m/s and the severe wind load that experienced on Jeddah is 34.8 m/s Wind tunnel tests by scale modelliing is done Due to Y legged shape continous tapering reduce the formation of vortex around structure Inorder to predict the exact variation of wind above 600 m certain tests are done Historical Surface wind Record Air Balloon Sounding Wethear Research Forecast model Wind Modelling High Frequency Force Balance (HFFB)-1:800 scale Model which is to measure forces at base in Early stage analysis-Rigid model High Frequency Pressure Integration(HFPI)-1:600 scale model to measure effect of pressure at the base HFPI- 1:400 Model for just the Spire, Half model becuase in previous test the tower is very thin Aero Elastic Model - 1:600 scale model- scaled every properties Design is done by considering the worst case scenario of all the tests Dampers Tuned mass dampers are provided on the top closed spire since the wind is very high above 650 m Similarly Tuned mass dampers are provided for the observatory sky deck Structural Health Monitoring Since this is a state of art project, immense study, care, and evaluation are needed to assure the quality of structure, material, and the components used. Various procedures are given to monitor structure in the short term during construction and in the long term to take care of all details of motion. By using the feedback after the construction of the tower we can measure the deflection and behavior of the real structure to improvise the design condition of the scaled model and mathematical model. Structural Health Monitoring For PIles Pile testing is done by pile loading to measure settlement and stress at the base of the pile after the construction. Measuring devices are embedded in the pile to measure the details. Also, the above details should be measured periodically in months during the construction so that everything is in control, to ensure no settlement more than the limit. For Raft Concrete behavior details like differential temperature development in the core and surface and strength developed to measure these concrete cube of 4.5 meters, are required to measure long term hydration and heating are under control for the real raft. Structural Health Monitoring Also, load cells are provided on each wing and central part to make sure the stress developed is within the limit. For overall pile and raft foundation settlement data is collected to check whether it's under limit during the period of construction and after it too. To ensure Verticality and vertical deformation To ensure the verticality, survey equipment at the level of the raft at different locations and make sure it exactly is defined as per plan during each stage of construction. Also, vertical shortening due to elastic, creep and shrinkage strain is measured as a relative change in height of the floor with respect to the assumed origin. It is measured after the construction and during construction. Structural Health Monitoring To ensure horizontal shortening and tapering of the tower As the height increases the tower size is tapered continuously so the change in height should be made sure while making the formwork it should be done by surveying with respect to the well-established origin. To measure horizontal deflection due to elastic, creepage, and shrinkage shortening strain is also done by surveying. Wall Stress Here measure the stress developed due to loading by strain gauge at various locations to measure the stress indirectly check this during the construction and after it and make sure it falls below the limit. Structural Health Monitoring Steel spire The top part of the tower is made of steel, and its connection is made of welding, so it should be inspected thoroughly before and after welding whether it's perfect or not, to avoid sudden brittle failure(lamellar Tearing). What should the owner do? Hire a third party to ensure that the plan is ok and every work is done according to the plan for better inspection. After the construction, the owner should compare the results of FEM, the physical model, and the real structure to make sure that the different limits for stress and load are not exceeded or not. These can be considered as the acceptance criteria Structural Health Monitoring Conduct routine checkups for all structural elements, crack development in concrete checks for the cause and do remedial measures. Life of the Structure As per the plan, the life of the structure is 100 years, as per the plan which is conservative. So during each month the environment and the corresponding changes, deflection, and measurements are fed to the Finite Element Model to mimic the structure and can predict how much more the structure can be sustained. Comparison with Burj khalifa Comparison with Burj khalifa Both Structures have Neo-Futurism architectural style Jeddah Tower Lloca Potential Tallest building with height ~ 1 Km Will consist of 167 floors Preliminary cost - 1.23 billion USD Located in Jeddah, Saudi Arabia. Burj Khalifa Loa Tallest man-made free-standing structure with height 829.8m It consists of 163 stories The total construction cost was $1.5 billion USD Located in Dubai, United Arab Emirates. Comparison with Burj khalifa Jeddah Tower Lloca Burj Khalifa Loa605 m Top floor height - 668m Aspect ratio - 12:1 Contains no column Tower tapers Continously Slab thickness of 250 mm Estimated to use 80,000 tonnes of steel Top floor height - 605m Aspect ratio - 9:1 Contain super cylinder column at the wing end Tower tapers at specific location 330,000 m3 of concrete and 39,000 tonnes of steel were used Comparison with Burj khalifa References https://global.ctbuh.org/resources/papers/download/20-case-study-kingdomtower-jeddah.pdf https://global.ctbuh.org/resources/papers/download/2384-case-study-kingdomtower-jeddah.pdf https://global.ctbuh.org/resources/papers/download/20-case-study-kingdomtower-jeddah.pdf https://global.ctbuh.org/resources/papers/download/2387-from-supertall-tomegatall-analysis-and-design-of-the-kingdom-tower-piled-raft.pdf https://global.ctbuh.org/resources/papers/download/2900-saudi-arabia-jeddahcity-and-jeddah-tower.pdf https://www.youtube.com/watch?v=GJLjjTfJjWQ THANK YOU