Impact of inclined columns on the performance of reinforced concrete structures: Methodological comparison

As of now, the load-bearing systems in reinforced concrete structures differ for aesthetic reasons. Inclined columns are typically employed in building design for various configurations. The literature indicates that the limited research conducted primarily uses response spectrum analysis about inclined columns. The current research uses multi-modal pushover and time-history nonlinear analytic approaches to comparatively evaluate the effects of real earthquakes on structural behavior. This work aimed to examine the performance of reinforced concrete structures with inclined columns affected by earthquake loads via nonlinear analysis. A total of four distinct 17-storey building models were developed, comprising one reference and three inclined column buildings. For modeling, columns located on the outside axes were constructed with an inclination. The different angles of column inclinations (79o and 84o), the storeys where the inclined columns end (9 and also 17), and nonlinear analytical methods were evaluated as parameters. Linear and nonlinear assessments were performed to ensure that the building design complies with the standards set out by the Türkiye Building Earthquake Code (TBEC). The inclined column design was discovered to reduce effective relative storey drift values, increase stiffness, and reduce ductility demand. It also altered the region where the damage was concentrated. As the inclination angle of the columns increased, the displacement capacities enhanced, the load-bearing capacity decreased, and the formation of plastic hinges diminished. Building models with inclined columns demonstrated superior performance relative to standard column building models. In the multi-mode pushover analysis, buildings with inclined columns up to the ninth story met the advanced performance target, whereas other models failed. None of the building models evaluated by non-linear time history analysis have satisfied the performance criteria. TBEC indicates that both methodologies are applicable in performance analysis. Nonetheless, it is evident that disparate results were yielded by the two analytical methods. Consequently, it was determined that all analytical methodologies must be considered regarding safety when assessing building performance.