Civil Engineering/Slab vibration

Advertisement

Expert: - 2/18/2009


Question
The following is a real case that occurred on a particular residential building site. A slab 6.0m by 5.0m was designed as a two way spanning slab and it was found the latter should be 150mm thick. But after construction, one could feel the vibrations caused while walking on the slab. Reinforcement and deflection were within the limit as per BS8110.

So what do you think went wrong? Any suggestion and solution??

Answer
Hi Murvin,

The short answer is that the assessment was flawed, as in order to limit deflection/vibration problems, the slab should have been at least 175-200mm thick for the spans you mentioned, especially if the slab is not an internal span (i.e. is an isolated or edge span).

If the strength is proven to be OK, then you can either ignore the vibration (as one does say in car parks), or else prop the slab and scabble the top surface and apply a structural screed on top of say 25-50mm thick, using a good bonding agent.

Civil Engineering

All Answers

Answers by Expert:

Ask Experts

Volunteer

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)

©2012 About.com, a part of The New York Times Company. All rights reserved.