Building damage during nearby construction: Forensic analysis

The paper presents a case history of a 5-storey building, seriously damaged during construction of a nearby structure. Founded on spread footings on soft clayey soil, the building was functional for nearly 30 years. When construction of an adjacent 4-storey RC building begun, its infill walls sustained shear failure. The shear cracks were inclined at 45°, being characteristic of differential settlements, and the neighboring construction was deemed to be the cause of failure. During the present forensic investigation, additional cracks were detected, also inclined at 45° but towards the opposite direction. Internal floor measurements were conducted, revealing that the maximum differential settlement of 5 cm is accompanied by 2.4 cm of differential settlement to the opposite direction. A number of construction defects were detected, with the most important being the superficial foundation of the building and the absence of tie beams. To quantify the contribution of each factor to the observed failure, the neighboring structures are simulated through finite elements, modeling nonlinear soil response with a Cam-clay model, validated against the conducted measurements. It is shown, that the shear failure of the infill walls is primarily due to construction defects, with the neighboring construction playing a secondary role.