Seismic performance and restoring force modeling of adobe block walls strengthened with near-surface-mounted wooden strips

To meet the technical demand for “strengthening with original materials and restoring the original appearance as far as possible” in the architectural appearance protection of a large number of existing adobe buildings, a near-surface-mounted (NSM) wooden strip strengthening technique was proposed for adobe block walls. To evaluate its seismic performance, five 1:2.5 scale adobe block wall specimens were designed and fabricated: one unstrengthened control and four strengthened with different NSM wooden strip schemes. Comparative horizontal low-cycle cyclic loading tests were then conducted. The effects of these schemes, including single-sided and double-sided strengthening, clinch-nail connections, and cross-interlocking connections, on the seismic failure modes and seismic performance of the walls were investigated. A restoring force model for adobe block walls strengthened with NSM wooden strips was established, and the economic cost of the proposed strengthening technique was analyzed. The results show that NSM wooden strip strengthening did not change the dominant seismic failure mode of the adobe block walls. However, it effectively delayed crack development and reduced the collapsed area of the walls. The most significant improvements were observed in the deformation capacity and cumulative energy dissipation, with increases of 24.9%–75.1% and 61.3%–188.1%, respectively. The load-bearing capacity and ductility were also improved by 6.5%–15% and 8%–15.7%, respectively. In addition, the cumulative energy dissipation of the walls with cross-interlocking connections was 12%–37% higher than that of the walls with clinch-nail connections. The proposed restoring force model can reasonably capture the main hysteretic response and stiffness degradation characteristics of the strengthened walls at different stages. The proposed NSM wooden strip strengthening technique also demonstrates good economic feasibility, and the strengthening schemes can be flexibly selected according to different engineering application scenarios.