Seismic Design Philosophy and Codes Questions and Answers

Answer: C

Assessing a building already standing is a different problem from designing a new one, since the geometry and materials are given and the question is what to add. IS 15988 provides the assessment procedure and the strengthening options, while IS 13935 covers repair and strengthening more broadly.

Answer: D

Much of the country's housing stock is built in stone or brick with weak mortar, and this standard sets out bands, corner reinforcement and opening limits appropriate to it. Earthen and adobe construction is covered separately by IS 13827.

Answer: A

A mason building a house without a designer cannot apply a load combination, so the guidance takes the form of rules about bands, corner reinforcement, wall lengths and opening sizes. Such construction houses a large part of the population and has accounted for much of the loss of life in past earthquakes.

Answer: B

Rather than a single code force and an implicit expectation, the designer and client agree on performance levels such as immediate occupancy or life safety, each paired with a level of hazard. The analysis then demonstrates that those objectives are met, usually by a nonlinear procedure.

Answer: C

Structural damage is negligible and services remain largely functional, so occupants can return immediately. It is a more demanding objective than life safety, which accepts substantial damage provided the structure stands and the occupants can get out.

Answer: D

At this level the building has very little margin left and may not be repairable, but it has not come down and the occupants have survived. It is the objective normally paired with the rarest and most severe level of shaking considered.

Answer: A

Operational means the building and its services carry on working, immediate occupancy allows minor repairs, life safety accepts substantial structural damage, and collapse prevention leaves the structure barely standing. The sequence is also one of decreasing cost to achieve.

Answer: B

The ground accelerates beneath the building, and the inertia of the building's own mass generates the lateral force. This is why heavy construction is penalised in seismic regions and why reducing mass is one of the few measures that lowers demand without adding stiffness.

Answer: C

Wind acts as a pressure on the faces of a building, so a large light building can be governed by wind while a small heavy one is governed by earthquake. Recognising which case governs saves a great deal of unnecessary work.

Answer: D

Moment frames, shear walls, braced frames and their combinations make up this system, and the response reduction factor is assigned to it rather than to the building as a whole. Identifying it clearly is the first step in any seismic design.