September 26, 2014 Dr. Linda Hanagan Lhanagan.engr.psu.edu

Transcription

1 September 26, 2014 Dr. Linda Hanagan Lhanagan.engr.psu.edu Dear Dr. Hanagan, This is Xiaodong Jiang. This following report was written for Technical Report 2 for AE 481 W. Technical report 2 includes the detailed structural loads determination analysis for Xyston Inn hotel, located in Brooklyn, NY. This report includes typical roof bay, floor bay, exterior wall loads, snow loads, lateral wind and seismic loads. Thank you for reviewing this report. I look forward to discussing it with you in the near future. Sincerely, Xiaodong Jiang Enclosed: Technical Report II of Xyston Inn.

2 Technical Report II Xiaodong Jiang Structure Option Advisor: Dr. Linda Hanagan September 26, 2014

3 Table of Contents Table of Contents 1 Building Abstract 2 Excusive Summary 3 Site and Location Plan 4 Reference Documents 5 Gravity Load 6 Typical Roof Bay 7 Typical Floor Bay 8 Typical Exterior Wall 9 Non-Typical Dead Load and Live Load 11 Snow Load 12 Lateral Load 16 Wind Load 17 Seismic Load 32 Conclusion 41 Assumption 42 Technical Report II 1

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5 Executive Summary Xyston Inn is a 17 story hotel building that will be located in Brooklyn, New York. The design of Xyston Inn is inspired by the varied character of this still developing part of the city. This 65,000 sq. ft. hotel will provide a comfortable spot for the people visiting New York. To create a bright and commodious lounge space, the first floor is designed with a height of 20 feet. The building also includes 16 hotel function floors and a mechanical floor which all have heights of 10 feet. The overall building height is about 215 feet. Beside these the building also has a cellar level 12 feet below street level. The building structure system is two-way reinforced concrete building with a reinforced concrete shear wall lateral system. The building is built on a bedrock level which has great allowable bearing capacity values. Due to the height of the building, the mat foundation consists the varied thickness between three feet and four feet. To transfer the building load to the foundation, 20 x 24 reinforced columns are commonly used for the cellar level and first floor level. The lateral system employs a reinforced concrete shear wall system at several location, through the building. To balance the architectural needs and great torsional force and moment, the structure adopts a 1 x 75 shear wall on the west to east direction. The concrete compressive strength of the shear wall also varies along the height of levels. On the north to south direction, the lateral system consists of several separated shear walls which have varying lengths from 10 feet to 26 feet. To design the building structure system, the loads considered in this building design include live loads, building dead loads, snow loads, wind loads, seismic loads, and lateral soil loads. The live load, dead load and snow load are also known as the gravity load which is caused by gravity, and acts on vertical direction. The wind load and seismic load are known as the lateral load, which is the load caused by wind or ground motion; those loads are acting directly on the lateral direction, but they also have some effect on the vertical direction. The lateral soil load is also lateral load, but it only effects the structure underground. Structure design is based on the 2008 New York City Building Codes for general structure design. The details of concrete elements are based on ACI Building Code ; and the load calculations follows ASCE 7-10 requirements. Technical Report II 3

6 Site Plan and Location Plan Brooklyn, New York Technical Report II 4

7 Reference Documents The codes and other documents used in preparation of this report are include: ASCE 7-10 Wind and Seismic Provisions AISC Steel Manual 14 th edition Material Unit Weight Table Technical Report II 5

8 Gravity Load Technical Report II 6

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18 Lateral Load -Wind Technical Report II 16

19 Lateral Load Wind There are several wind load cases need to be considered. Case 1: Overall Lateral windward force. Case 2: Uplift force on green roof. (20 ft. above ground level). Case 3: Uplift force on the roof of 14 th story (153 ft. above ground level). Case 4: Uplift force on the roof above 18 th story (215 ft. above ground level). Case 5: Overall Lateral leeward force. Note: wind forces acting on side ward walls cancel each other out. The internal pressures acting on the internal side of exterior wall also cancel each other out. Only the windward force and leeward force can cause building to overturn. Technical Report II 17

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22 Wind Load (Excel Calculation & Details-01, N-S direction) Technical Report II 20

23 ********This Excel sheet might only work for risk category II ********* Technical Report II 21

24 Table: Story Shear and Overturning Moment - Windward Technical Report II 22

25 Note: Story Shear = Involved Height * B * Pressure Accumulative Shear = sum of the shear from the stories above Moment = Story Shear * Height Technical Report II 23

26 Table: Story Shear and Overturning Moment - Leeward Technical Report II 24

27 Wind Load (Excel Calculation & Details-02, W-E direction) Technical Report II 25

28 ********This Excel sheet might only work for risk category II ********* Technical Report II 26

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30 Note: Kzt = 1 Calculated in step 3-c Gf = 3.31 Calculated in step 3-d Cp From Step 6 Technical Report II 28

31 Table: Story Shear and Overturning Moment - Windward Note: Story Shear = Involved Height * B * Pressure Accumulative Shear = sum of the shear from the stories above Moment = Story Shear * Height Technical Report II 29

32 Table: Story Shear and Overturning Moment - Leeward Technical Report II 30

33 Therefore, the base shear and overturning moment due to two orthogonal direction wind load is listed on the table below. The wind load of this project causes large numbers of story shear, base shears and overturning moments. The evaluation of lateral system shall use the shears values to determine whether the lateral system of this project, shear wall system, are adequate to carry the lateral load. And the evaluation of building structure system might also need to consider whether the structure of this project needs any design details to tight the structure down due to the large values of overturning moment. To determine the controlling lateral loading condition, the seismic force calculation is also required. The flowing pages show the calculation of seismic base on ASCE 7-10 requirements. Technical Report II 31

34 Lateral Load- Seismic Technical Report II 32

35 Lateral Load - Seismic Technical Report II 33

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40 Seismic Load Determination and Tables Base on ASCE 7-10 Technical Report II 38

41 Note: Wt is from Hand Calculation with conservative assumptions story shear = Fx = 0.01 Wx Accumulated Shear = Sum of story shear above Moment = Story shear * Height Therefore, the base shear is 111 kips due to seismic load, and overturning moment is 10,834 k-ft. due to seismic load. It comes out that wind load controls. Technical Report II 39

42 Note: Forces shown on the right are not equal, and only depended on story weight (base on F = 0.01 Wx) The table below shows the comparisons between wind load and seismic load base on the base shear and overturning moment. The result shows that wind load is the controlling lateral load condition. According to base shear results, the base shear due to wind is about 1300% to 2600% of the base shear due to seismic. Total Base Shear, kips Overturning Moment, k-ft N-S Direction W-E Direction Seismic (both direction) ,252 49,111 11,051 Technical Report II 40

43 Conclusion Gravity Load: Typically, roof bay s dead load is 130 psf. And floor bay s dead load is 130 psf. The maximum possible live load in this project is 100psf. Design flat roof snow load is 20 psf, and design drift snow load can reach 55 psf; therefore, the gravity design of roof slab shall be proved to be able to carry 55 psf snow load. Lateral Load: Wind load controls the lateral loading condition. The base shear shall be designed for 812 kips (unfactored), and the design overturning moment is about 96,252 k-ft (un-factored) on the north-to-south direction. The base shear shall be designed for about 414 kips (un-factored), and the design overturning moment is about 49,111 k-ft (un-factored) on the west-to-east direction. Due to the high uplift pressures, the roof bay might need to be designed for uplift pressure. Even though the self-weight of concrete slab seems to be able to help, the uplift pressure could cause the slab to fail by surface tensile stress. Therefore, the shear reinforcement of roof slab should consider the wind uplift pressure effects. Due to the high value of overturning moment, the building might need to be tighten down. The tension in lower floors LFRS elements and non-lfrs elements shall also be considered. Technical Report II 41

44 Assumptions Wind Load: 1. Simplified rectangular boxes are considered as the design building shape. 2. Assume Cp = -0.9, or for uplift wind loads on both N-S and W-E directions on level line H = 20 feet. 3. Assume Cp = -0.8, or for uplift wind loads on both N-S and W-E directions on level line H = 153 feet. 4. Assume Cp = -1.3, or for uplift wind loads on both N-S and W-E directions on level line H = 215 feet. 5. Winds acts on the orthogonal directions of building exterior wall. Seismic Load: 6. Storage weight portion is negligible. 7. Partition load is 12 psf on floor from the structure drawing. 8. Use 75 psf mechanical room s live load for the equipment load in mechanical rooms. 9. Use 57 x rectangular shape for roof plan area calculation. 10. Use 140 psf for the roof over 14 th floor. 11. Building damping ratio is 5%. Technical Report II 42