Completing Confined Masonry

Requested Research

  • Main request. Complementing of the existing knowledge about confined masonry, and bring it together in one complete, fully correct and practical manual.
  • A literature and practice research of all different kinds of confined masonry that are being used in the world.
  • Comparison of confined masonry with; and confined masonry without tie beams and tie columns around doors and windows.
  • Comparison of different tooth types and dimensions of wall endings, versus no tooth at all. Which one is most effective?
  • Seismic analysis of confined masonry with bricks and blocks in different sizes, shapes and materials. Such as cement blocks and stabilized earth bricks.
  • Correct plans and detailing of confined masonry buildings in different configurations, such as an L-shaped building, or adding a veranda.
  • Correct schematic drawings of the steel reinforcements in all beams and columns, over several storeys. Including comparison of confined masonry with; and confined masonry without steel reinforcements between brick layers.
  • Full analysis and optimization of the hostel design in confined masonry that was built by Smart Shelter Foundation in Nepal, prior to the earthquakes in 2015.

Status of Research

Open for students and professionals of Structural Engineering and Earthquake Engineering. Send us an email to request the full assignment sheet via this link.

Past and current research:
2016 – 2017: Amber Tan, Nanyang Technological University in Singapore

Background: Confined Masonary

Confined masonry has historically proven to behave well in earthquakes. The basics of confined masonry are not too difficult and the wall dimensions, thicknesses and openings can be calculated, as well as the required amount of steel reinforcements. This earthquake resistant type of construction is recommendable for multi-storey buildings with concrete slabs, up to 3 floors high.

Although the end result looks similar, confined masonry works significantly different than RCC frames. Firstly there is a difference is the sequence of building; RCC frames are built first and then filled up with bricks. The frames are mostly subjected to moment forces that doesn’t go along with the stiff infill. With confined masonry the walls are built first with a toothed wall end, and the tie columns and beams are cast later, thus creating shear panels. This connection between column and panel seems to be the key to success, and needs further research.

Interestingly, this system is cheaper and less complicated than making a concrete frame earthquake resistant! Confined masonry uses about the same amount of bricks and concrete, but far less steel reinforcement is needed. Also, the connections are a lot easier to explain to the local labourers.

We applied the basics of confined masonry ourselves at our hostel for blind students in Nepal. A description can be found here on our Smart Shelter Foundation website.

Further Research

The existing knowledge about confined masonry is quite elaborate, especially compared to most low-tech construction types. Therefore we feel that it should be possible to complement the missing information relatively fast.

However, we see that some of the published information is contradicting and confusing. For instance, we need to have more certainty about the need for extra tie beams and columns around openings. Which weaving patterns of the steel reinforcements are the correct ones? Also detailed and practical design information is missing difficult to fins. Such as the right way to make an L-shaped building, and what happens at the gap between two building volumes.

Most important seems the research on the connection between masonry and the confinements. We are interested in using different block sizes and materials as wall infill. What is the maximum possible dimension of a tooth, which tooth pattern is best? Do we need those teeth at all? Maybe it is just a matter of fine tuning, yet there is still a lot to discover!

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