Civil Engineering/seismic basics

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Expert: - 11/27/2008


Question
QUESTION:
Hi, i need help in seismic design... Our instructor refuses to teach us seismic analysis...and we don't know where to begin.. Unfortunately, we don't have resources.. What is the basic principle in seismic analysis? Do you know any helpful sites? Tnx for ur kind help..

ANSWER: Hi Roy,

There are a lot of useful websites for this, such as:

http://www.wbdg.org/resources/seismic_design.php

and

http://www.nicee.org/EQTips.php



---------- FOLLOW-UP ----------

QUESTION:  here's my prob.. i have a three-storey reinforced moment-resisting frame..interior columnns exntend to the 2nd floor only while exterior columns extend all the way up..the building plan is an L-shaped..in static-eqiuvalent procedure, the horizontal force is to be distributed according to the rigidity of each frame..supposing unequal columns sizes and distances, how do i determine determine the rigidity/stiffness of each frame so as to dist. the forces horizontally using statc-equalent proc.?

Answer
Hi Roy,

If you have an analysis package, then model the building in 3-D, apply a horzontal displacement in each orthogonal direction, and check from the analysis outout what shear force is being resisted at the base of each column as each floor- that will tell you how the seismic forces will be distributed, as the stiffer frames/columns will resist the higher proportion of lateral seismic loading.

If you do not have such software, then you can estimate the stiffness of each sub-frame by manual moment distribution means, or very approximately by taking the second moment of area of each column and dividing that by it's height- i.e I/L.

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Arshad Khan

Expertise

I can answer any questions to do with civil and structural engineering consultancy and construction industry in East Africa and the Middle East, and specifically with the analysis and design of reinforced concrete structures. My particular expertise is in the aseismic design and optimisation of tall buildings.

Experience

Employment history: 36 years in Construction and consultancy in the UK, Kenya, Tanzania, Uganda, Ethiopia, Eritrea, South Africa, Somalia, Zambia, Austria, Bahrain, Kuwait, Doha and the U.A.E.

Organizations
.Fellow of Institution of Structural Engineers (UK) .Fellow of Institution of Civil Engineers(UK) .Member of the Institution of Engineers, Kenya .Registered Engineer, ERB, Kenya .Member of the Architectural Association of Kenya (Engineers Chapter) .Chartered Engineer (UK)

Publications
•1984: International Conference on the Art and Practice of Structural Design, London •1994: 3rd Int. Kerensky Conference in Structural Engineering, Singapore •2008: International Conference on High-Rise Towers, Abu Dhabi

Education/Credentials
BSc, 1st Class Hons, in Building Engineering, University of Bath, UK MSc in Concrete Structures and Technology, University of London. Diploma of Imperial College, UK.

Awards and Honors
•Science Congress Special Award (for 2-seater Hovercraft - 1968) •Institution of Civil Engineers Award for outstanding performance at Bath University (1975) •Concrete Society Postgraduate study Bursary Award (1976) •Consular Representative for British High Commission, Nairobi. (1995 to 1998) •Examiner for Institution of Civil Engineers Professional Interviews, Nairobi. (1997 to 1998) •Branch Representative in Vienna for PI assessment for Inst. of Struct. Engrs. (1999 to date)

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