TECHNICAL REPORT Report on the Practical Training submitted in partial fulfilment of the requirements for the degree of MASTER OF TECHNOLOGY in STRUCTURAL ENGINEERING by ANURADHA PAGADODDI (182ST003) ASWATHY SHAJI (182ST006) CHIPPY EDWARD (182ST009) KEERTHI V T (182ST014) Organization Providing Training: M/s STUP Consultants Pvt. Ltd., Old Airport Road, Bengaluru DEPARTMENT OF CIVIL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA SURATHKAL, MANGALORE -575025 JULY 2019
DECLARATION We hereby declare that the PG Practical Training Report is being submitted to the National Institute of Technology Karnataka, Surathkal in partial fulfilment of the requirements for the award of the Degree of M Tech in Structural Engineering is a bonafide report of the Practical Training work carried out by us. Place: NITK, Surathkal ANURADHA PAGADODDI (182ST003) Date: 30/07/2019 ASWATHY SHAJI (182ST006) CHIPPY EDWARD (182ST009) KEERTHI V T (182ST014) Department of Civil Engineering
CERTIFICATE This is to certify that the PG Practical Training Report entitled ANALYSIS AND DESIGN OF HOSTEL BUILDING submitted by ANURADHA PAGADODDI (182ST003), ASWATHY SHAJI (182ST006), CHIPPY EDWARD (182ST009), KEERTHI V T (182ST014) as the record of work carried out by them, is being accepted as the PG practical training report submission in partial fulfilment of the requirements for the award of degree of Master of Technology in Structural Engineering in the Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal. Dr. Prashanth M H Faculty Advisor Professor and Head Department of Civil Engineering
ACKNOWLEDGEMENT It gives me immense pleasure to express sincere gratitude and appreciation for Mr. SHASHIDHAR D CHIKODI, Associate Vice president, STUP Consultants Pvt. LTD., Bengaluru, for giving me the opportunity to attend the internship program. I would also like to express my deepest appreciation for Mr. MURALI RANGAPPA, Manager-HR, STUP Consultants Pvt. Ltd., Bengaluru, for arranging the internship program and for his availability to help us whenever required. I extend my heartfelt gratitude to Mr. RAVI KIRAN, Design Engineer, STUP Consultants Pvt. Ltd., Bengaluru, for providing us with detailed information about the project and for guiding us through every step and making the internship challenging and rewarding. I also do not like to miss the opportunity to acknowledge the contribution of Dr. PRASHANTH M H, Professor, Department of Civil Engineering, National Institute of Technology, Karnataka, and Dr. K SWAMINATHAN, Professor and Head, Department of Civil Engineering, National Institute of Technology, Karnataka for their wholehearted support and giving me the opportunity to organise and attend the internship program. I offer my sincere thanks to STUP Consultants Pvt. Ltd. for letting me work in the company and making me feel comfortable throughout the course of the internship and am very grateful to my family and friends who have been instrumental in the successful completion of this report.
ABSTRACT Structural building engineering includes all structural engineering related to the design of buildings and is primarily driven by the creative manipulation of materials and forms and the underlying mathematical and scientific ideas to achieve an end which fulfills its functional requirements and is structurally safe when subjected to all the loads it could reasonably be expected to experience. In this inplant training modelling, analysis, design and detailing of a hostel building is done using ETABS and AutoCAD softwares. All the elemental dimensions were taken in accordance with the codal provisions and all the dead load, live load calculations and wind load calculations were done manually and earthquake loads are taken by software itself.
CONTENTS ACKNOWLEDGEMENT ABSTRACT List of figures List of tables 1. INTRODUCTION 2. ABOUT THE COMPANY 3. ABOUT THE PROJECT 4. SOFTWARES USED 4.1 ETABS 2015 Ultimate 4.2 AutoCAD 2013 5. GENERAL 6. MODELLING IN ETABS 6.1 Materials and Sections Used 6.1.1 Beams 6.1.2 Columns 6.1.3 Slabs 7. LOADS AND ANALYSIS 7.1 Dead load 7.2 Live load 7.3 Wind load analysis 7.3.1 Auto Wind load calculation in X direction 7.3.2 Auto Wind load calculation in Y direction 7.4 Seismic load analysis 7.4.1 Auto seismic load calculation in X direction 7.4.2 Auto seismic load calculation in Y direction
7.5 Load combinations 7.6 Analysis Result 8. DESIGN AND DETAILING 8.1 Design and detailing of Beam 8.1.1 Design of Beam B8 at Storey 1 8.1.2 Detailing of Beam B8 8.2 Design and detailing of column 8.2.1 Design of Column C15 at Storey 2 8.2.2 Detailing of Column C15 8.3 Design of Slab 8.3.1 Two way slab F16 8.4 Design of Footing 8.5 Analysis and Design of a Staircase 9. CONCLUSIONS REFERENCES
LIST OF FIGURES Fig.3.1 Ground floor plan Fig.3.2 First floor plan Fig.3.3 Second floor plan Fig.3.4 Terrace floor plan Fig.3.5 Overhead tank level plan Fig.3.6 Roof plan Fig.6.1 Plan of first storey from ETABS Fig.6.2 3D view of the modelled building in ETABS Fig.6.3 3D Rendered view of modelled building in ETABS Fig.7.1 3D view of assigned frame loads from ETABS Fig.7.2 Plan view of assigned live load more than 3 kN/m2 Fig.7.3 Plan view of assigned live load upto 3 kN/m2 Fig.7.4 Plan view of assigned roof load on storey 3 Fig.7.5 Applied Storey forces due to wind load in X direction Fig.7.6 Applied Storey forces due to wind load in Y direction Fig.7.7 Applied Storey Forces due to seismic load in X direction Fig.7.8 Applied Storey Forces due to seismic load in Y direction Fig.7.9 Displacement for envelope load combination Fig.7.10 Bending moment diagram for envelope load combination Fig.7.11 Shear force (2-2) diagram Fig.7.12 Shear force (3-3) diagram Fig.7.13 Torsion diagram from ETABS (comb: 0.9DL + 1.5WLx) Fig.8.1 Longitudinal and Cross sectional view of B8 Fig.8.2 Longitudinal section of C15 Fig.8.3 Cross sectional view of C15
Fig.8.4 Plan showing bottom reinforcement (F16) Fig.8.5 Plan showing top reinforcement (F16) Fig.8.6 Sectional view of short span Fig.8.7 Sectional view of long span Fig.8.8 Footing plan details (joint 10) Fig.8.9 Footing section details (joint 10) Fig.8.10 Footing in one way shear Fig.8.11 Footing in two way shear Fig.8.12 Plan of staircase Fig.8.13 Loads acting on flight 1 Fig.8.14 Loads acting on flight 2 Fig.8.15 Loads acting on flight 3 Fig.8.16 Detailing of flight 2
LIST OF TABLES Table 7.1 Imposed loads Table 7.2 Applied storey forces due to Wind load in X direction Table 7.3 Applied storey forces due to Wind load in Y direction Table 7.4 Calculated Base shear due to seismic load in X direction Table 7.5 Applied storey forces due to seismic load in X direction Table 7.6 Calculated Base shear due to seismic load in Y direction Table 7.7 Applied storey forces due to seismic load in Y direction
CHAPTER 1 INTRODUCTION In this era of growing needs for enhanced infrastructural facilities, well designed and well-constructed building structures are inevitable. In spite of the architectural appeal, functioning of the structures should also be given a proper thought. For fruitful development in the fields of analysis and design, a number of softwares has been arisen since these works when done manually can be tiresome. Some of the softwares helping in analysis and design of the structures are STAAD PRO (Structural Analysis and Design), ETABS (Extended Three-dimensional Analysis of Building Structures), SAP, SAFE etc. Apart from these softwares such as AUTOCAD, REVIT, ANSYS etc. are also helpful. Prior to construction, a structure has to be modelled, analysed, designed and detailed without fail for a structure to perform at the desired level. Various loads acting on a building structure includes gravity loads and lateral loads such as wind load, earthquake loads. Loads such as snow loads, temperature loads etc. can also be in effect depending on the location, exposure conditions etc. The structure should be capable of resisting the loads coming on it without failure or at least giving ample time for rescue before failing. While analysis and designing, care should be taken that both the serviceability and ultimate load conditions are met without fail. It should also be durable and aesthetically pleasing, without compromising the safety and sustainability.
CHAPTER 2 ABOUT THE COMPANY STUP is a French acronym that stands for “Societe Technique Pour l’ Utilization de la Precontrainte”, meaning Technical Corporation for the Utilization of Prestressed Concrete. The company was established in Paris in 1944 to spread knowledge of prestressed concrete and other inventions of the renowned French Engineer, M. Eugene Freyssinet. The company was established in India in 1963 and was inspired and laid by the late C. R. Alimchandani. STUP has served over 10,000 clients in 37 countries on projects of tremendous diversity such as the Road Master Plan in Bangladesh, the water supply system in Laos highways in Kuwait, sports facilities in the UAE, offshore facilities and hospital facilities in Oman, nuclear reactors, airports and power plants in India etc. STUP is a full service project delivery consultancy company offering integrated planning, comprehensive building design, engineering and project management services for buildings, power, transportation, telecommunications, commercial, institutional, recreational and manufacturing facility infrastructure, and is an international firm with over 1200 professionals in more than 20 offices and global project locations. STUP’s wide range of resources and expertise offer comprehensive and single umbrella solutions (incorporating building design, infrastructure engineering, mechanical, electrical and HVAC services) to technically challenging projects and services from planning to construction for local and national governments, international financing institutions, private sector owners, contractors and public sector institutions.
CHAPTER 3 ABOUT THE PROJECT The Industrial training was done at STUP Consultants Pvt. Ltd., Old Airport Road, Bengaluru, under the guidance of Mr. Shashidhar D Chikodi, Associate Vice President and Mr. Ravi Kiran Design Engineer consisted of modelling, analysis, design and detailing of a hostel building. The training includes modelling, analysis, design and detailing of a G+2 residential building. The total height of the building is 16m. First storey is 3.9 m high, and the subsequent storeys are 3.3 m and 3.25 m high. The building laterally extends 20.45m in one direction and 19.25 m in the other direction. An open well staircase with three flights is used to connect between floors. Water tank is situated at an elevated height of 3.9 m from the third storey. Various plans of the building are as shown in Fig. 3.1. to Fig. 3.6 Fig.3.1 Ground floor plan
Fig.3.2 First floor plan Fig.3.3 Second floor plan
Fig.3.4 Terrace floor plan Fig.3.5 Over head tank level plan
Fig.3.6 Roof plan
CHAPTER 4 SOFTWARES USED 4.1 ETABS 2015 Ultimate ETABS is an engineering software product that caters to multi-story building analysis and design. It is a FEA software created by CSI. It is used to model and analyse structures mainly buildings and their components to see how a building behaves under various loads. Modelling tools and templates, code-based load prescriptions, analysis methods and solution techniques, all coordinate with the grid like geometry unique to this class of structure. Basic or advanced systems under static or dynamic conditions may be evaluated using ETABS. For a sophisticated assessment of seismic performance, modal and direct-integration time-history analyses may couple with P-Delta and Large Displacement effects. Nonlinear links and concentrated PMM or fiber hinges may capture material nonlinearity under monotonic or hysteretic behavior. Intuitive and integrated features make applications of any complexity practical to implement. ETABS a coordinated and productive tool for designs which range from simple 2D frames to elaborate modern high-rises. Modeling features of ETABS are; templates for global-system and local-element modeling, customized section geometry and constitutive behavior, grouping of frame and shell objects, link assignment for modeling isolators, dampers, and other advanced seismic systems, nonlinear hinge specification, automatic meshing with manual options, editing and assignment features for plan, elevation, and 3D views. Output and display formats are also practical and intuitive. Moment, shear, and axial force diagrams, presented in 2D and 3D views with corresponding data sets, may be organized into customizable reports. Also available are detailed section cuts depicting various local response measures. Global perspectives depicting static displaced configurations or video animations of time-history response are available as well. ETABS also features interoperability with related software products, such as importing from technical drawing software and exporting to various file format.
4.2 AUTOCAD 2013 AutoCAD is a commercial computer-aided design and drafting software application. Developed and marketed by Autodesk, AutoCAD was first released in December 1982 as a desktop app running on micro computers with internal graphic controllers. AutoCAD is the standard design software used in engineering, architecture, interior design and construction industries. Designers and drafters use it to create two-dimensional and three- dimensional computer drawings. The software supports both 2D and 3D formats. AutoCAD is used for designing, drafting, documentation, analysis, defining work flows, surveying and mapping of civil engineering projects. It can be also used to make accurate 2D drawings and to render 3D models to help in the visualisation of the end product. Plans ranging from buildings, manholes, reinforcement details of RC structures or any other civil engineering drawings can be done using AutoCAD.
CHAPTER 5 GENERAL The hostel building is a Residential Building as per the classification by National Building Code of India (NBC 2015). To start with, the given plan was well studied and the salient features were noted down. With the lightings from the studies, various configurations of beams and columns were tried and beam-column layout was made. Since no major challenges were found, simple moment resisting connections using beam- column framework has been used. For fixing the preliminary dimensions of structural elements such as beam, column and slab, various provisions from IS 456:2000, IS 875:1987, IS 1893 (part 1) :2016 as well as IS 13920:2016 were considered. For wind load analysis IS: 875 (Part 3) – 2015 was used Initial sizing of the elements were done using the relevant codal provisions and this was used for modelling of the structure. Two tanks were used as domestic water tank and fire water tank respectively placed at the roof of staircase room.
CHAPTER 6 MODELLING IN ETABS Taking dimensions from the given architectural plan the hostel building is modelled in ETABS 2015 software. Modelling of the structure requires special attention and accuracy since the same modelled building has to be loaded, analysed and designed. So to get exact building size, grid systems were drawn first and then the frame elements were added. Then each frame element is assigned with the preliminary sections as per the Indian Standard codes by checking serviceability criterias. 6.1 Materials and sections used Here concrete of grade M30 and steel of grade Fe 500 having modulus of elasticity 27386.12788 MPa and 2x105 MPa were used for the given building. The unit weight of steel and concrete respectively are 76.9729 kN/m3 and 24.9926 kN/m3. 6.1.1 Beams Five types of beam sections were used. 230mm x 400mm to 400mm x 600mm sections were used. Mid landing beams are also provided in staircase. Beam sections of both continuous and simply supported were assigned in areas of necessity. 6.1.2 Columns Rectangular columns of 400mm x 400mm, 450mm x 500mm and 500mm x 550mm were also used as required. All columns are restrained in position and direction. 6.1.3 Slabs Slab is modelled as a thin shell element than a membrane element. In order to take care of the deflection limit specified by IS code, an overall depth of 150mm were proposed for all slabs in first 3 storeys except for watertank. At the level of water tank, slabs of 250 mm thickness was used since the loading is very high at this level.
Fig.6.1 Plan of First Storey from ETABS Fig.6.2 3D view of the modelled building in ETABS
Fig.6.3 3D Rendered view of modelled building in ETABS
CHAPTER 7 LOADS AND ANALYSIS Every structure is under the action of different types of loads. The structure should be safe in all possible load applications. There are different types of loads and the action of these depends upon the building model, topographic characteristics, seismic zones etc. the different types of loads and their effect is depicted below. 7.1 Dead Load In the modelling, only beams, columns and slabs were taken. For these elements, the dead loads were inbuilt and for other elements such as partition walls, parapet and other elements, the dead weight was calculated and these loads were assigned as dead load on the concerned beams. The dead load acting on a building was taken as per IS: 875 (Part-1) - 1987. 200 mm and 100 mm thick brick walls were used as partition wall. Unit weight of these walls were taken as 18.85 kN/m3. Self weight calculated by ETABS Wall load on beams = height x wall thickness x density of masonry Wall load on main beam at plinth and first storey = 2.7 x 0.2 x 18.85 = 10.18 kN/m Wall load on secondary beam at plinth and first storey = 2.7 x 0.1 x 18.85 ≈ 5.09 kN/m Wall load on main beam at second storey = 2.65 x 0.2 x 18.85 ≈ 10 kN/m Wall load on secondary beam at second storey = 2.65 x 0.1 x 18.85 ≈5 kN/m Parapet load at terrace = 1 x 0.2 x 25 = 5 kN/m Water tank wall load = 1.5 x 0.2 x 25 = 7.5 kN/m Lift wall load = 2.4 x 0.2 x 18.85 ≈ 9.05 kN/m Super dead load (floor finishes) 1 kN/m2 on all slabs Super dead load (weight of stairs, finishes) on waist slab of stair = 2.875 kN/m2 Superimposed dead loads were taken from IS 875 (part 1):1987 and was assigned to slab sections.
Fig.7.1 3D view of assigned frame loads from ETABS 7.2 Live load The use of the term ‘live load’ has been modified to ‘imposed load’ to cover not only the physical contribution due to persons but also due to nature of occupancy, the furniture and other equipments which are a part of the character of the occupancy. Various loads considered are as tabulated. Table 7.1 Imposed loads Bed rooms 2 kN/m2 Kitchen 3 kN/m2 Store rooms 5 kN/m2 Service rooms 5 kN/m2 Living cum dining 4 kN/m2 Bath rooms and Toilets 2 kN/m2 Corridors, Passages and Staircase 3 kN/m2
Live load due to water tank was also added on to the corresponding slab. On roofs, to which access was provided, a live load of 1.5 kN/m2 and on slabs without access a live load of 0.75 kN/m2 was also added. Live loads on different slabs are show in Fig.7.2. Fig.7.2 Plan view of assigned live load more than 3 kN/m2 Fig.7.3 Plan view of assigned live load upto 3 kN/m2
Fig.7.4 Plan view of assigned roof load on storey 3 7.3 Wind load analysis For any structure above ground level wind load effect also have to be taken care. The wind speed at any height never remains constant and is fluctuating and the wind speeds have been worked out for 50 years return period. As height of the structures increases the wind pressure on the building also increases. Therefore their distributions along storeys are of importance while analyzing a structure. Also wind will be acting in all directions. For calculation point of view we considered wind along two perpendicular directions of the building, and its change in direction also taken into account. For the analysis of wind load, diaphragm was defined and assigned on to all the floors. The location of the building suggests a basic wind speed of 39 m/s and belongs to terrain category II. The building belongs to category B as per classification by IS 875 (part 3):2015. Internal and external pressure coefficients were found and the windward and leeward pressure coefficients in x and y directions were calculated to be 0.7 and 0.25 respectively.
7.3.1 Wind load calculation in X direction Lateral wind loads for load pattern wind x is calculated according to IS875 (part 3):2015. Exposure parameters Exposure form = Diaphragms Structure Class = Class B Terrain category =Category 2 Wind Direction = 0 degrees Basic Wind Speed, Vb [IS Fig. ] Vb = 39 meter/sec Windward Coefficient, Cp,wind Cp,wind = 0.7 Leeward Coefficient, Cp,lee Cp,lee = 0.25 Internal pressure coefficient, Cpi Cpi = 0.2 Top storey = Storey 3 Bottom storey = Base Factors and Coefficients Risk coefficient, k1 k1 = 1 Terrain, height and structure size factor, k2 k2 = 1.054 Topography Factor, k3 k3 = 1 Lateral Loading Design Wind Speed Vz = Vbk1k2k3 Vz = 41.106 Design Wind Pressure Pz = 0.6 Vz2 Pz = 1013.82 Wind load F = (Cpe - Cpi) x A x Pz
Fig.7.5 Applied Storey Forces due to Wind Load in X – Direction Table 7.2 Applied Storey Forces due to Wind Load in X - Direction Storey Elevation X-Dir Y-Dir M kN kN Storey3 10.45 18.82 0 Storey2 7.2 31.96 0 Storey1 3.9 32.21 0 Plinth 0.6 19.03 0 Base 0 0 0 7.3.2 Wind load calculation in Y -direction Lateral wind loads for load pattern wind Y is calculated according to IS875 (part 3):2015. Exposure parameters Exposure form = Diaphragms Structure Class = Class B Terrain category =Category 2
Wind Direction = 90 degrees Vb = 39 meter/sec Basic Wind Speed, Vb [IS Fig. ] Cp,wind = 0.7 Windward Coefficient, Cp,wind Cp,lee = 0.25 Leeward Coefficient, Cp,lee Cpi = 0.2 Internal pressure coefficient, Cpi k1 = 1 Top storey = Storey 3 k2 = 1.054 Bottom storey = Base k3 = 1 Factors and Coefficients Risk coefficient, k1 Vz = 41.106 Terrain, height and structure size factor, k2 Pz = 1013.82 Topography Factor, k3 Lateral Loading Design Wind Speed Vz = Vbk1k2k3 Design Wind Pressure Pz = 0.6 Vz2 Wind load F = (Cpe - Cpi) x A x Pz Fig.7.6 Applied Storey Forces due to Wind Load in Y - Direction
Table 7.3 Applied Storey Forces due to Wind Load in Y- Direction Storey Elevation X-Dir Y-Dir M kN kN Storey3 10.45 0 22.43 Storey2 7.2 0 33.95 Storey1 3.9 0 34.21 Plinth 0.6 0 20.214 Base 0 0 0 7.4 Seismic load analysis All structures need to be designed for appropriate earthquake effects as per IS: 1893 (Part 1) - 2016. The requirement of seismic analysis depends upon the seismic zone of the existing building. Return period of earthquake and the life span of the building, the type of building under consideration. Here the given structure is proposed at the seismic zone III and medium soil, so the earthquake analysis is unavoidable. Earthquake induced forces will be in all directions. The predominant direction of vibration is usually horizontal. So seismic forces acting along two horizontal directions were taken. 7.4.2 Auto seismic load calculation in X Direction The calculation below presents the automatically generated lateral seismic loads for load pattern seismic X according to IS1893:2016, as calculated by ETABS. Direction and Eccentricity T = 0.417 sec Direction = X Eccentricity Ratio = 0% for all diaphragms Structural Period Period Calculation Method = User specified User Period T= 0.075h0.75 Factors and Coefficients
Seismic Zone Factor, Z [IS Table 2] Z = 0.16 Response Reduction Factor, R [IS Table 7] R=5 Importance Factor, I [IS Table 6] I = 1.2 Site Type [IS Table 1] =II Seismic Response Sa/g = 2.5 Spectral Acceleration Coefficient, Sa/g[IS 6.4.5] Ah = (ZISa/g)/2R Equivalent Lateral Forces Seismic Coefficient, Ah [IS 6.4.2] Table 7.4 Calculated base shear due to seismic load in X direction Direction W(kN) Vb (kN) X 16332.5318 783.9615 Fig.7.7 Applied Storey Forces due to Seismic load in X Direction
Table 7.5 Applied Storey Forces due to Seismic load in X Direction Storey Elevation X-Dir Y – Dir M kN kN Storey3 10.45 391.8064 0 Storey2 7.2 314.0207 0 Storey1 3.9 78.1344 0 Plinth 0.6 0 0 Base 0 0 0 7.4.3 Auto seismic load calculation in Y Direction The calculation below presents the automatically generated lateral seismic loads for load pattern seismic Y according to IS1893:2016, as calculated by ETABS. Direction and Eccentricity T = 0.417 sec Direction = Y Z = 0.16 Eccentricity Ratio = 0% for all diaphragms R=5 Structural Period I = 1.2 Period Calculation Method = User specified User Period T= 0.075h0.75 Sa/g = 2.5 Factors and Coefficients Seismic Zone Factor, Z [IS Table 2] Response Reduction Factor, R [IS Table 7] Importance Factor, I [IS Table 6] Site Type [IS Table 1] =II Seismic Response Spectral Acceleration Coefficient, Sa/g[IS 6.4.5] Equivalent Lateral Forces
Seismic Coefficient, Ah [IS 6.4.2] Ah = (ZISa/g)/2R Table 7.6 Calculated base shear due to seismic load in Y direction Direction W(kN) Vb (kN) Y 16332.5318 783.9615 Fig.7.8 Applied Storey Forces due to Seismic load in Y Direction Table 7.7 Applied Storey Forces due to Seismic load in Y Direction Storey Elevation X-Dir Y – Dir M kN kN Storey3 10.45 0 391.8064 Storey2 7.2 0 314.0207 Storey1 3.9 0 78.1344 Plinth 0.6 0 0 Base 0 0 0
7.5 Load combinations A judicious combination of the loads keeping in view the probability of their acting together, and their disposition in relation to other loads and severity of stresses or deformations caused by combinations of the various loads is necessary to ensure the required safety and economy in the design of a structure. The following serviceability and ultimate load combinations were used here. 1.5 DL + 1.5 LL DL + LL 1.5 DL ± 1.5 WLx DL ± WLx 1.5 DL ± 1.5 WLy DL ± WLy 1.5 DL ± 1.5 ELx DL ± ELx 1.5 DL ± 1.5 ELy DL ± Ely 0.9 DL ± 1.5 WLx DL + .8LL ± WLx 0.9 DL ± 1.5 WLy DL + .8LL ± WLy 0.9 DL ± 1.5 ELx DL + .8LL ± ELx 0.9 DL ± 1.5 ELy DL + .8LL ± Ely 1.2 DL + 1.2 LL ± 1.2 WLx 1.2 DL + 1.2 LL ± 1.2 WLy 1.2 DL + 1.2 LL ± 1.2 ELx 1.2 DL + 1.2 LL ± 1.2 ELy Finally an envelope was also added as a combination incorporating all the load combinations linearly added 7.6 Analysis Results The model was analysed for various load combinations and the results obtained were used to know the structural behavior of the model. The deflections of various components were checked to know if they fall within the limits prescribed by IS 456:2000. Also the long term deflections with the effect of creep and shrinkage were also calculated for specific beams and were found to fall within the limits. The following figures shows the bending moment diagram and shear force diagram for the combination consisting of the envelope.
Fig.7.9 Displacement diagram Fig.7.10 Bending moment diagram for envelope load combination
Fig.7.11 Shear force (2-2) diagram Fig.7.12 Shear force (3-3) diagram
Fig.7.13 Torsion diagram from ETABS (comb: 0.9DL + 1.5WLx)
CHAPTER 8 DESIGN AND DETAILING The analysed model was designed as per the IS 456:2000 and the entire model was checked if it passed the design. If not, the sections were modified and checked again till no beam or column is overstressed. 8.1 Design and Detailing of Beam A beam is a structural element that primarily resists loads applied laterally to the axis of the beam. Here, design of a beam as well as detailing of the same is dealt with. 8.1.1 Design of Beam B8 Storey 1 IS: 456 – 2000 Beam Section Design Table 8.1: Beam8 Element Details Type: Ductile Frame Level Element Section Combo Station Length LLRF ID ID Loc (mm) 1 Storey B2- 4850 1 B8 400x550- envelope 4600 M30 Table 8.2: Section properties b (mm) h (mm) bf (mm) ds (mm) dct (mm) dcb (mm) 0 40 40 400 550 400
Table 8.3: Material properties EC (MPa) fck (MPa) Lt.Wt Factor fy (MPa) fys (MPa) (Unitless) 500 500 27386.13 30 1 Table 8.4: Design Code Parameters ɣc ɣs 1.5 1.15 Table 8.5: Factored Forces and Moments Factored Mu3 kN- Factored Tu kN- Factored Vu2 kN Factored Pu kN m m 148.0725 0 17.8521 24.0044 Table 8.6: Design Moments, Mu3 & Mt Factored Moment Factored Mt kN- Positive Moment Negative Moment kN-m m kN-m kN-m 17.8521 33.5356 51.3877 -151.6933 Table 8.7: Design Moment and Flexural Reinforcement for Moment, Mu3 & Tu Design Design -Moment +Moment Minimum Required -Moment +Moment Rebar Rebar mm² Rebar mm² Rebar mm² mm² kN-m kN-m Top (+2 Axis) -151.6933 728 0 728 578 Bottom (-2 51.3877 578 236 0 578 Axis) Table 8.8: Shear Force and Reinforcement for Shear, Vu2 & Tu Shear Ve kN Shear Vc kN Shear Vs kN Shear Vp Rebar Asv /s kN mm²/m 232.5787 79.0365 249.5599 89.8235 1355.98
Table 8.9: Torsion Force and Torsion Reinforcement for Torsion, Tu & VU2 Tu Vu kN Core b1 mm Core d1 mm Rebar Asvt /s mm²/m kN-m 24.0044 148.0365 340 490 896.82 8.1.2 Detailing of Beam B8 Fig.8.1 Longitudinal and Cross sectional view of B8
8.2 Design and Detailing of Column A column is a structural member which transfer compressive load (axial or eccentric) to the elements below. 8.2.1 Design of Column C15 at Storey 2 Table 8.10: Column Element Details Type : Ductile Frame Level Element Section Combo Station Length LLRF ID ID Loc (mm) 0.863 Storey C1- 3300 2 C15 500X500- envelope 2750 M30 Table 8.11: Section Properties b (mm) h (mm) dc (mm) Cover (Torsion) (mm) 30 500 550 60 Table 8.12: Material Properties Ec (MPa) fck (MPa) Lt.Wt Factor fy (MPa) fys (MPa) (Unitless) 500 500 27386.13 30 1 Table Design Code Parameters ɣc ɣs 1.5 1.15
Axial Force and Biaxial Moment Design for Pu, Mu2, Mu3 Design Pu Design Mu2 Design Mu3 Minimum M2 Minimum M3 Rebar Area Rebar % kN kN-m kN-m kN-m kN-m mm² 137.2641 -15.3394 -20.5868 3.0427 3.2715 2200 0.8 Axial Force and Biaxial Moment Factors K Factor Length Initial Additional Minimum (Unitless) (mm) Moment Moment Moment kN-m kN-m kNm Major 0.842407 2750 14.5514 0 3.2715 Bend(M3) 2750 Minor 0.775761 6.7891 0 3.0427 Bend (M2) Shear Design for Vu2, Vu3 Shear Vu Shear Vc Shear Vs Shear Vp Rebar kN kN kN kN Asv/S mm2/m Major, Vu2 26.1666 132.2895 98.0004 26.1666 131.4684 96.8004 68.7243 554.22 Minor, 68.7243 Vu3 609.64
Joint Shear Check/ Design Joint Shear Shear Shear Joint Shear Ratio Shear Vtop kN Vu Tot Vc Area Unitless Force 169.7269 cm2 1506.2 0.113 kN 404.023 37 2750 0.307 Major 1314.5 2400 Shear, 0 22.1667 341 Vu2 Minor Shear, 0 41.7755 Vu3 Beam/ Column Capacity Ratio Major Ratio Minor Ratio 0.405 1.17 Additional Moment Reduction Factor k Ag cm2 A sc cm2 Puz kN Pb kN Pu kN k Unitless 1628.4053 137.2641 1 2750 22 4537.5 Additional Moment Consider Length Section KL/Depth KL/Depth KL/Depth Ma Factor Depth Ratio Limit Exceeded (mm) Major Yes 0.833 4.212 12 No Bending Yes 550 0.833 4.267 12 No (M3) 500 Minor Bending (M2)
8.2.2 Detailing of Column C15 Fig.8.2 Longitudinal section of C15 Fig.8.3 Cross sectional view of C15
8.3 Design of Slab 8.3.1 Two way slab F16 Short span, lx = 3.5 m Long span, ly = 3.625 m Overall depth, D = 150 mm Characteristic strength of concrete, fck = 30 MPa Characteristic strength of steel, fy = 500 MPa Diameter of bars along short span, φ = 10 mm Diameter of bars along long span, φl = 10 mm Live load, LL =4 kN/m2 Dead load of floor finishing, DLf = 1kN/m2 Clear cover provided = 20 mm Number of discontinuous edges, Nd = 1 ly/lx = 1.305 < 2 Slab will be designed as two-way slab Step 1: calculation of loads and effective span Clear span along short span = 3.1 m Clear span along long span = 3.325 m Effective depth (from span/depth), dx = 125 mm Effective depth, dy = 115 mm Dead load, DLw = 3.75 kN/m2 Total dead load, DL = 4.75 kN/m2 Live load, LL = 4 kN/m2 Factored load, Wu = 13.125 kN/m2 Effective short span, lx = 3.225 m Effective long span, ly = 3.44 m
R = ly / lx = 1.06 ≈ 1.1 Step 2: Calculation of bending moment and shear force αx+ = 0.033 Mx+ = 4.504 kNm αx- = 0.044 Mx- = 6 kNm αy+ = 0.028 My+ = 3.82 kNm αy- = 0.037 My- = 5.05 kNm Step 3: Check for depth Xu,max/d = 0.46 Depth required for given moment = 38.77mm Depth provided is adequate and slab is under reinforced Step 4: Calculation of reinforcement (short span) Mx+ = 4.504 kNm Mx- = 6 kNm Effective depth, dx = 125 mm Fck = 30 MPa Fy = 500 MPa Diameter of bar, φ = 10 mm Area of positive reinforcement, Astx+ = 180 mm2 Area of negative reinforcement, Ast - = 112 mm2 x Spacing of reinforcement provided = 300 mm Reinforcement provided = 261.667 mm2 Percentage of reinforcement, Ptx = 0.209% Step 5: Calculation of reinforcement (long span) My+ = 3.82 kNm My- = 5.05 kNm Effective depth, dy = 115 mm
Fck = 30 MPa Fy = 500 MPa Diameter of bar, φ = 10 mm Area of positive reinforcement, Asty+ = 180 mm2 Area of negative reinforcement, Asty- = 103 mm2 Spacing of reinforcement provided = 300 mm Reinforcement provided = 261.667 mm2 Percentage of reinforcement, Pty = 0.227% Ptx > 0.12 % and Pty > 0.12% ⸫Reinforcement is adequate Step 6: Check for shear Average effective depth, d =120 mm Factored shear force, Vu = 18.76 kN Nominal shear stress, τv = 0.156 N/mm2 Pt= 0.209% fck = 30 N/mm2 Design shear strength of concrete, τc = 0.331N/mm2 (IS: 456 – 2000, Table 19) Overall depth, d = 150 mm k (from IS: 456 – 2000, Cl: b-5.2.1.1) =1.30 Modified shear strength of concrete, kτc = 0.429 N/mm2 Check kτc > τv OK Slab is safe in shear Step 7: Check for deflection Area of steel required, Astx = 150 mm2 Area of steel provided, Aprov = 261.667 mm2
Effective depth, d = 125 mm Percentage of reinforcement, Pt = 0.209% Fs = 166.24 N/mm2 Modification factor, k =2 Provided span/depth ratio = 25.8 Permissible span/depth ratio = 40 40 > 25.8 OK Slab satisfies the deflection criteria Step 8: Check for development length Fck = 30 N/mm2 Fy = 500 N/mm2 Diameter of main reinforcement = 10 mm Design bond stress of concrete, τbd = 2.4 N/mm2 (to be increased by 60% for deformed bars and further increase 25% for compression steel). Development length, Ld = 453.125 mm Ld/3 = 151.04 mm L0 = 8* φ = 80 mm Mnl = Mx+/2 = 2.252 kNm Vu = 18.76 kN 1.3(Mnl/Vu) + l0 = 236 mm Embedded length of bars = width of support – clear cover = 300 -20 = 280 mm 280 mm < 151.04 mm So provide hooks or bends.
Main reinforcement: provide 10mm diameter bars @ 300mm c/c Distribution reinforcement: provide 10mm diameter bars @ 300mm c/c Fig.8.4 Plan and sectional view of bottom reinforcement (F16)
Fig.8.5 Plan showing top reinforcement (F16) 8.4 Design of Footing Column dimensions = 500mm x 550mm fck = 30 MPa fy = 500 MPa SBC = 200 kN/m2 Pz = 533.88 kN Mx = Mx’+ Px x depth = 65.3 kNm My = 16.785 kNm Preliminary dimension: Assume a square footing of size 2m x 2m Footing length, L = 2m Footing breadth, B = 2m Thickness of footing, t = 600mm Clear cover to Reinforcement = 75mm Main bar diameter of footing =16mm
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