Many buildings experience stresses, such as seismic forces, which can compromise their structural integrity. Several methods or products can be used to repair the building so that its structural performance can be enhanced. This article discusses some of the structural repair options.
Use of FRP Systems
Fibre-reinforced polymer (FRP) sheets can be used to add structural strength to a building that has been found to be failing. For example, the structural columns of a building can start developing cracks if that building starts being used as a storage space for heavy machinery. The weight-bearing capacity of those columns can be improved by wrapping them with an FRP fabric. This added strength comes from the superior tensile strength of the composite materials from which the FRP sheets are made.
Span Shortening
Some structures can start weakening when a building or structure has large expanses of material that are supported at a few points. For example, the basement roof of an underground parking garage can start sagging if a large section of the roof is unsupported by columns. This can put the building at the risk of total collapse when the basement roof is overwhelmed by the weight of the floors above it. Span shortening by adding extra support columns in the parking garage can prevent that problem. The additional columns will increase the channels through which the weight of the building is dispersed into the foundation. Cast-in-place concrete or steel columns are examples of ways to do this.
Section Enlargement
The structural strength of a building can also be improved using a technique called section enlargement. This method involves making sections, such as slabs and columns, thicker so that they can support heavier loads than the original designs permitted. For example, more concrete can be poured around a concrete beam to increase its diameter.
Bonded Steel Elements
Another way to improve the structural performance of the components of a building, such as concrete columns, is bonding steel onto those structures. Mechanical fasteners and epoxy adhesives are used during this strengthening process. The mechanical fasteners ensure that the bonded element will also disperse the loads imposed upon the columns. The fasteners also act as extra protection for the bond if the adhesives fail. This method works in the same way as using FRP sheets.
Each of the strengthening techniques/products above have their own benefits and drawbacks. Work with a structural engineer to evaluate the different options available before selecting the best for the structural repair of your building. Contact a construction engineering firm to learn more.
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