Open Access
Table 1
Summary of the retrofit methods for aged masonry buildings.
| Retrofitting method | Advantages | Disadvantages |
|---|---|---|
| Surface strengthening using steel wire mesh and mortar. [33–36] |
Help reduce cracks. Effective in enhancing seismic performance through improved strength and ductility. |
Long construction time and difficult to maintain. Slight debonding may happen during construction. |
| Chemical grouting and cement grouting. [37–39] |
Help restore the structural integrity and increase strength. Maintain the original load-bearing system and appearance. |
Irreversibility after reinforcement. Incompatibility between old and new materials may lead to durability issues. |
| Carbon fibre reinforced polymers (CFRP) [40–42] |
Light, self-weight, and flexible in design and construction. Help increase ductility and energy dissipation. |
Debonding and delamination may happen between the material and structural layer. |
| Adding ring beams and additional columns [43–45] |
Help improve seismic performance, load-bearing capacity, and deformation capacity. | Inability to avoid the formation of cracks. Long construction time. Increase in structure self-weight. |
| Steel patching around the structural components. [42,46–49] |
Fast construction. Without the enlargement of the cross-section of the components. Help improve shear capacity, stiffness, ductility, and seismic performance. |
Complexity during construction. Corrosion of steel. The heavyweight of steel plates during transportation, handling, and installation. |
| Strengthening using engineered cementitious composite (ECC) * [50–54] |
Flexible in application scenarios and fast construction. Help increase structural strength, ductility, and seismic performance. |
The quality of construction, such as the skill level of labour, is critical. The steel reinforcing bar may fall off from ECC. ECC shotcrete does not help increase stiffness. |
| Strengthening using ultra-high performance concrete (UHPC) * [1,55–57] |
Help improve the integrity, stiffness, and seismic resistance. Less intervention in the structure. |
Limited design codes. The complex manufacturing process of raw materials. Low maturity level. |
| Strengthening using highly ductile fibre reinforced concrete (HDC) *
[58–64] |
Help enhance deformability, ductility, and stiffness. Application in real projects Low impacts on the cross-sectional area and weight of existing members. |
Does not help energy dissipation in confined walls. Tensile strength is highly sensitive to different fibres. Availability of raw material. |
| Strengthening using fibre-reinforced polymer (FRP) + polypropylene (PP) * [65–67] |
Help increase ductility, deformation capacity, and residual strength. Fast construction There is no requirement for construction personnel. PP improves the brittleness of FRP. |
High requirements for epoxy. Not suitable for all brick walls. FRP may fall off the wall surface. |
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