1st Edition
Structural Dynamics in Earthquake and Blast Resistant Design
Focusing on the fundamentals of structural dynamics required for earthquake blast resistant design, Structural Dynamics in Earthquake and Blast Resistant Design initiates a new approach of blending a little theory with a little practical design in order to bridge this unfriendly gap, thus making the book more structural engineer-friendly. This is attempted by introducing the equations of motion followed by free and forced vibrations of SDF and MDF systems, D’Alembert’s principle, Duhammel’s integral, relevant impulse, pulse and sinusoidal inputs, and, most importantly, support motion and triangular pulse input required in earthquake and blast resistant designs, respectively. Responses of multistorey buildings subjected to earthquake ground motion by a well-known mode superposition technique are explained. Examples of real-size structures as they are being designed and constructed using the popular ETABS and STAAD are shown. Problems encountered in such designs while following the relevant codes of practice like IS 1893 2016 due to architectural constraints are highlighted. A very difficult constraint is in avoiding torsional modes in fundamental and first three modes, the inability to get enough mass participation, and several others. In blast resistant design the constraint is to model the blast effects on basement storeys (below ground level). The problem is in obtaining the attenuation due to the soil. Examples of inelastic hysteretic systems where top soft storey plays an important role in expending the input energy, provided it is not below a stiffer storey (as also required by IS 1893 2016), and inelastic torsional response of structures asymmetric in plan are illustrated in great detail. In both cases the concept of ductility is explained in detail. Results of response spectrum analyses of tall buildings asymmetric in plan constructed in Bengaluru using ETABS are mentioned. Application of capacity spectrum is explained and illustrated using ETABS for a tall building. Research output of retrofitting techniques is mentioned. Response spectrum analysis using PYTHON is illustrated with the hope that it could be a less expensive approach as it is an open source code. A new approach of creating a fictitious (imaginary) boundary to obtain blast loads on below-ground structures devised by the author is presented with an example.
Aimed at senior undergraduates and graduates in civil engineering, earthquake engineering and structural engineering, this book:
Explains in a simple manner the fundamentals of structural dynamics pertaining to earthquake and blast resistant design
Illustrates seismic resistant designs such as ductile design philosophy and limit state design with the use of capacity spectrum
Discusses frequency domain analysis and Laplace transform approach in detail
Explains solutions of building frames using software like ETABS and STAAD
Covers numerical simulation using a well-known open source tool PYTHON
1.1 Types of Analysis
1.2 Modelling of a Dynamic System
1.2.1 Degrees of Freedom
1.3 D’Alembert’s principle
Chapter 2 Single Degree of Freedom Systems(S.D.F Systems)
2.1 Introduction
2.2 Free and Forced Vibrations
2.2.1 Free Vibrations
2.2.2 Damped Free Vibrations
2.2.3 Logarithmic decrement
2.3 Forced Vibration of a Damped Single Degree
of Freedom
2.4 A Single-Degree-of-Freedom System Subjected to
Support Motion
2.5 Rayleigh’s Method to Obtain Natural Frequency
2.6 Response in Frequency Domain and Laplace
Transformation
2.7 Problems
2.8 Exercise Problems
Chapter 3 Two Degree of Freedom System
3.1 Forced Response of Damped Two Storeyed Building
3.2 Exercise Problems
Chapter 4 Force Transmitted to the Support
4.1 Exercise Problems
Chapter 5 Duhamel’s Integral
Chapter 6 Modal Analysis
6.1 Multi Degree of Freedom Systems Subjected To
External Dynamic Forces- Modal Analysis
6.2 A Multi-Storeyed Building Subjected To Ground
Motions-Modal Analysis
6.3 Problems
6.4 Exercise Problems for Chapters 5 and 6
Chapter 7 Earthquake Resistant Design
7.1 Introduction
7.2 Structural Analysis
7.3 Structural Model
7.4 Shear building
7.5 Response Spectrum
7.6 Capacity Spectrum
Chapter 8 Inelastic Vibration Absorber Subjected to Earthquake
Ground Motion
8.1 Introduction
8.2 The Linear Elastic Vibration Absorber
8.3 The Hysteric Vibration Absorber
8.4 Structural Model and the Equations of Motion
8.5 Numerical Studies
8.6 Analysis of Results
8.6.1 Response of the Absorber Mass
8.6.2 Response History Curves
8.6.3 Hysteric Energy Dissipation
8.6.4 Influence of Viscous Damping
8.6.5 Maximum Ductility Response Spectra
8.7 Conclusions
Chapter 9 Inelastic Torsional Response of a Single-Storeyed Framed
Structure-Two Degree-of-Freedom System
9.1 Introduction
9.2 Earthquake Response of Elastic Structure with Coupled
Translational and Torsional Motions
9.3 Structural Model
9.4 Equations of Motion
9.4.1 Solution of the Equations of Motion
9.4.2 Parameters Considered in the Study
9.4.3 Details of the Computer Programme
9.5 Discussion of Results
9.5.1 Influence of Eccentricity Envelopes of
maximum frame ductility
9.5.2 Influence of Yield Strength
9.5.3 Influence of P-Δ Effect
9.5.4 Influence of Strengthening the Exterior Frames
9.5.5 Response History Curves
9.5.6 Energy Dissipation due to Hysteresis
9.5.7 Maximum Ductility Response Spectra
9.6 Summary and Conclusions
Chapter 10 Inelastic Torsional Response of a Single-Storeyed Framed
Structure-Three Degrees-of-Freedom System
10.1 Introduction
10.2 Structural Model
10.2.1 Yielding Behaviour
10.3 Equations of Motion
10.4 Solutions of the Equations of Motion
10.4.1 Parameters Considered in the Study
10.5 Discussion of Results
10.5.1 Influence of Eccentricity
10.5.2 Influence of Yield Strength qiuo = qivo = qi and
period (Tiu = Tiv = Ti)
10.5.3 Time- Response Curves
10.6 Summary and Conclusions
Chapter 11 Earthquake Resistant Design as per IS 1893:2016
11.1 Introduction
11.2 Project - 01
11.2.1 Introduction
11.2.2 Floating columns
11.2.3 Soft Storey
11.2.4 Building asymmetric in plan
11.2.5 Mass Participation factor
11.2.6 Conclusions
11.3 PROJECT - 02
11.3.1 Introduction
11.3.2 Analysis
11.3.3 Conclusions
11.4 Problems
Chapter 12 Miscellaneous Aspects
12.1 Introduction
12.2 Retrofitting Methods in RCC structures
12.2.1 Structure-level Retrofit
12.2.2 Addition of shear walls
12.2.3 Base Isolators
12.2.4 Addition of Steel bracing
12.2.5 Member-level retrofit
12.3 Response Spectrum analysis using PYTHON
12.3.1 About the programming language: PYTHON
12.3.2 History of PYTHON
12.3.3 Application of PYTHON - in Civil Engineering
12.3.4 Python Architecture
12.3.5 Python Libraries
12.3.6 Static loading problem using Python
12.3.7 Dynamic Loading problem
12.3.8 Response spectrum analysis of building using
PYTHON
12.4 Hybrid building under seismic forces
12.4.1 Introduction
12.4.2 Types of connections
12.4.3 Earthquake responses of Hybrid building
12.5 Analysis and design of blast resisting structures (IS
4991:1968)
12.5.1 General characteristics of blast and
consequences on structures
12.5.2 Loading effects due to blasts
12.5.3 Blast load on above ground structures (IS
4991:1968)
12.6 Response of RCC Asymmetric Buildings subjected to
earthquake ground motions
12.6.1 Structural Modelling
12.6.2 Modelling And Analysis Of Structural
Irregularities
Biography
B.K. Raghu Prasad retired as a professor from Civil Engineering deparetment of Indian Academy of Sciences, Bangalore, India and his areas of research are fracture mechanics of concrete, structural dynamics, earthquake resistant design, finite element and boundary element methods. He has more than 60 research papers to his credit and he has supervised more than 25 students for thier Ph.D degrees.
