Seismic Damage Investigation and Analysis of Buildings Following the M 5.5 Diebu Earthquake in Gansu Province

On 26 January 2026, a 5.5-magnitude earthquake occurred in Diebu County, Gansu Province, causing different degrees of damage and collapse to houses. To understand the damage characteristics and causes of typical buildings, a post-earthquake damage assessment was conducted on buildings in the epicentral area through field investigations of 16 urban buildings and rural houses in 10 natural villages. The results indicate that among the rural buildings, timber frame structures accounted for the largest proportion and suffered the worst damage, primarily manifested as overall collapse of enclosure walls, partial wall collapse, and wall cracking. Brick–wood structures and non-seismic fortification masonry structures suffered relatively minor damage, mainly characterized by cracks at the intersections of longitudinal and transverse walls, as well as diagonal cracks around door and window openings. In urban buildings, reinforced concrete frame structures are more prevalent, with damage primarily concentrated on infill walls, stairwells, suspended ceilings and decorative surfaces. In seismic-resistant masonry structures, the damage primarily involves the failure of non-structural components such as parapets and canopies. The primary causes of seismic damage are construction defects and the absence of seismic structural measures in self-built houses, insufficient seismic resilience in non-structural components of seismic-resistant structures, and the site amplification effect and secondary seismic hazards, which exacerbate the damage to buildings. Furthermore, improvement measures are proposed based on the seismic damage characteristics of different structures. These include conducting research on the construction techniques of Tibetan-style timber-frame houses, developing design and construction standards tailored to local conditions, and enhancing the seismic performance of non-structural components for seismic-resistant structures. The aim is to provide a scientific basis and engineering guidance for post-disaster reconstruction and earthquake disaster prevention in affected areas.