5-story Residential Building

Transcription

1 10/14/2015 First Project Experience Requirement Committee Interview 5-story Residential Building Vahid Babaei

2 Project title: 5-story residential building located in Rasht, Iran Consultant Company: Omran Sooleh Project Budget: $2,000,000 My position: Designer Project duration: 8 Months My responsibilities: Analyzed and designed concrete structure based on ACI (318-11) code and using ETABS 2013 and SAFE 12.3 Prepared CAD sheets with details Worked closely as a team member with architectural and mechanical engineers P a g e 1 17

3 Part 1: Introduction 1.1 Information of the project: 5-story residential building located in Rasht, Iran Height of each story is 3.2 m and the height of underground floor is 3 m Area of each floor: m 2 Structural system in one direction is moment frame and in another direction is shear wall Characteristics of materials: Concrete F c = 30 MPa E = 5000 f c = MPa Steel fy = 400 MPa E = MPa Loading codes: Dead and live loads according to 519 Iranian code Seismic load according to 2800 Iranian code 1.2 Structural design based on ACI 1.3 Software used ETABS and SAFE P a g e 2 17

4 Part 2: Loading 2.1 dead loads: Roof and floor weight: Mosaic Cement mortar Light weight Concrete Isolation Roof 600 kg/m2 Block Concrete Floors 650 kg/m2 External and internal walls: Brick Cement mortar Plaster Surrounding walls type kg/m 2 Rock Surrounding walls type kg/m2 Internal walls 100 kg/m2 P a g e 3 17

5 Stairs 735 kg/m2 Parapet walls 300 kg/m2 External wall loads subjected to the beams directly. If the load of internal wall is less than 275 kg/m2, it can be converted to distributed gravity load and subjected to the floor. 2.2 Live loads: According to Iranian code part 6 live load for residential buildings is 200 kg/m2 2.3 Snow load: The snow load is calculated as following formula: P r = C s P s Which Cs is related to roof slope and for this project it is 1 and Ps is a geographical factor and for this project it is 150 kg/m2. So P r = = 150 kg/m 2. But the max of live load and snow load should be chosen as live load. Therefore the final live load is 150 kg/m Elevator load is 2000 kg applied on columns located on the corners of elevator. 2.5 The load applied on beams from walls is calculated as following formula: (The height of the wall ) (the wieght ot the wall) (1 Opening ratio) Summary of gravity loads subjected to floors: Gravity loads distributed on floors Gravity loads distributed on roof P a g e 4 17

6 2.6 Wind load: According to Iranian Code part 6 the wind load is calculated as following formulas: q = 0.005V 2 V is wind speed km/hr P = C e C q q Ce is wind speed tolerance coefficient and C e = 1.6 ( Z 10 )0.24 Cq is shape of the building coefficient and it depends on position of building surfaces subjected to wind. F = P. A F is wind force and A is the surface subjected to wind C e C q Part 3: Seismic Load There are 2 kinds of seismic analysis: Static Analysis and Dynamic Analysis. Static seismic analysis is suitable for regular buildings less than 50 m height and for irregular buildings less than 5 story or less than 18 m. Regular is defined in plan and rigidity. Static analysis applied for this building. 3.1 Calculating seismic coefficient: V = ABI R A: Acceleration of the plan (it is a geographical factor depends on the risk of the earthquake) B: Response spectrum, I: Building importance factor, R: Reduction factor Based on 2800 code: I = 1, A = 0.3 In X direction (moment frame): R = 8 In Y direction (moment frame + shear wall): R = 9 P a g e 5 17

7 B = 1 + ( T T 0 ) if 0 T T 0 B = 1 + S if T 0 T T s B = (1 + S) ( T s T )2/3 if T T s T0, Ts and S are the factors depend on the kind of soil and risk of earthquake for location. In this project and based on the tables on 2800 code: T 0 = 0.15, T s = 0.7, S = 1.75, T = 0.05H 3/4 { in X direction: C x = in Y direction: C Y = Calculating seismic force on each floor: Because T in X and Y direction is less than 0.7 (s), Ft = 0 The seismic loads applied to the floors: P a g e 6 17

8 Part 4: Analysis 4.1 Assuming the initial sections for columns and beams according to code: l n 4d, b 0.3t, b 25 cm Columns for stories 1, 2, 3 Columns for stories 4, 5 and parapet Beams for stories 1, 2, 3 Beams for stories 4, 5 and parapet with with with with Shear walls: and Load patterns for analysis: Dead, Live, EX, EY, EPX = EX + eccen Y, ENX = EX eccen Y, EPY, ENY 4.3 Creating load combination based on ACI code. 4.4 After analyzing following results can be attained: Getting internal forces and moments for beam and columns. For example seismic forces subjected to each floor diaphragm is: P a g e 7 17

9 4.4.2 Control displacements and drifts for each floor: M 0.025H and M = 0.7R w M M M { for X direction for Y direction In stories 2 and 3 drifts are more than allowable rate so the size of the columns should be changed to cm Moment diagram in shear wall: Center of gravity and weight of each floor: P a g e 8 17

10 4.4.5 Shear forces and moments due to seismic loads for each floor: P a g e 9 17

11 Part 5: Design There are 2 methods for structural designing. Ultimate Strength Design and Load and Resistance Factor Design (LRFD). In this project based on ACI code, the first method is used. 5.1 Design beams: The beams should be designed for moment, shear and torsion Design for moment: ρ max = 0.25 or 0.75ρ b q = 0.85 [1 1 2M u 0.85 c f c bd 2] P a g e 10 17

12 5.1.2 Crack and deflection control: Deflection should be controlled based on ACI code. w 0.41 mm for internak beam w 0.34 mm for external beam Control for shear and torsion: P a g e 11 17

13 Total rebar area needed for beams: 5.2 Column design: Control buckling: M 1b is Min and M 2b is Max moment P a g e 12 17

14 5.2.2 Calculating shear and longitudinal bars: ρ max = 6% and ρ min = 1% Min shear bars: Min distance between shear bars: P a g e 13 17

15 Total area of rebar needed for columns on floor 3: 8d b 1 l 0 = min { small dimention of dcolumn mm P a g e 14 17

16 5.3. Design stairs: 5.4 Design shear wall: Control wall section: Tension rebar area: P a g e 15 17

17 Part 6: Some details P a g e 16 17

18 P a g e 17 17