Basics on Seismic Retrofitting of Historic Structures

Historic buildings are cultural assets, and they are worth preserving. Renovation and retrofitting of these buildings brings out several challenges, since the methods and materials used for the original construction of these buildings will not be similar to the conventional methods practiced these days.

Historic Building Retrofitting

In the process of seismic retrofitting, structural and non-structural historic materials and features should be retained and preserved; not just as museum artifacts, but also to fulfill their function. For example, reworking on the windows and doors in an old museum building.

If some features are to be removed for retrofitting, then it should be done carefully and should be reinstalled in the original location. Besides that, if some historic elements are damaged beyond repair, then they should be replaced with a compatible and similar substitute.

The entire retrofitted structure should be able to preserve the historic element of the building without compromising on the safety. It should be reversible wherever possible, to carry out the repair works.

Evaluation

If a historic building is located in an earthquake prone area, then it should be subjected to detailed seismic evaluation to avoid damage to life and property. To start with, check out the architectural features that need to be preserved such as staircases, mosaics, ornate ceilings, and murals. Spaces and areas that have lost their historic significance can be used for the installation of structural reinforcements.

Structural deficiencies such as lack of supporting beam, column, and vulnerable non-structural elements like interior partitions and chimneys, should be identified as well. As compared to structural elements, non-structural elements cause more costly damages in case of a mild earthquake. So proper care should be taken to fix them in position.

Retrofitting Work

The degree of potential risk of failure of a structure can be evaluated by checking the type of construction of a building. Adobe buildings and unreinforced masonry buildings have higher risk of collapse as compared to steel-framed or reinforced buildings.

Unreinforced masonry building can be saved by securing chimneys and parapets, and by securing the masonry walls to the floors. Support to the roof can be given by providing columns and shear walls. Buildings with regular shapes of plan, such as a rectangle or square, offer more resistance to earthquake as compared to buildings having irregular or complex plan.

Earthquakes come without any warning; so regular maintenance and repair works are all the more important to be carried out in order to keep a historical building safe in an earthquake prone area.

Posted on Tuesday, January 23rd, 2018.