In this exploration, we delve into the realm of earthquake-resistant construction known as Confined Masonry. The focus is on unraveling its structural components, highlighting key differences from traditional construction methods, shedding light on factors influencing seismic resistance, and discussing the advantages and applications of this innovative building approach.
Masonry walls play a pivotal role in transferring loads to the foundation and resisting horizontal earthquake forces. They act as bracing panels, ensuring the stability of the structure during seismic events.
These elements, such as tie-beams and tie-columns, provide essential restraint to masonry walls. They prevent complete disintegration, safeguarding the structure even in the face of a significant earthquake.
The slabs in confined masonry act as both gravity and lateral load transmitters to the walls. During earthquakes, they function akin to horizontal beams, referred to as diaphragms.
The plinth beam protects ground floor walls from excessive settlement in soft soil conditions, transferring the load from walls to the foundation.
The foundation, akin to conventional masonry, transfers the load from the structure to the ground.
| Features | Confined Masonry Construction | RC Frame Construction |
|---|---|---|
| Gravity and Lateral Load-Resisting System | Masonry walls bear both gravity and lateral loads. Confining elements are smaller in size than RC beams and columns. | RC frames resist loads through large beams, columns, and connections. Masonry infills are non-load bearing. |
| Foundation Construction | Strip footing beneath the wall and RC plinth band. | Isolated footing beneath each column. |
| Superstructure Construction Sequence | 1. Masonry walls are constructed first. 2. Tie-columns are cast in place. 3. Tie-beams are constructed on top of walls simultaneously with floor/roof slab construction. | 1. The frame is constructed first. 2. Masonry walls are constructed later and are non-structural. |
Studies indicate that higher wall density correlates with less damage during earthquakes. Minimum wall density requirements are specified in building codes based on traditional construction practices.
Lateral load resistance depends on the strength of masonry units and mortar. Walls constructed with grouted or solid units exhibit greater strength compared to those using low-strength bricks or ungrouted hollow block units.
Closely spaced transverse reinforcement in tie-columns enhances wall stability and ductility post-cracking, significantly influencing the seismic performance of confined masonry.
The provision of horizontal wall reinforcement in buildings with more than four stories improves wall ductility, resulting in a more uniform distribution of inclined shear cracks.
In conclusion, confined masonry stands as a testament to innovative earthquake-resistant construction, offering structural resilience and safety in regions prone to seismic activity.