Realtime Floor Eccentricity Reduction: A Desktop Application for Mass and Stiffness Manipulation

In seismic design, building configuration (especially mass and stiffness distribution) is crucial for mitigating earthquake damage. When there is an eccentricity between the center of mass (CM) and the Center of Stiffness (CS) of a floor, a twisting moment occurs. This moment causes dangerous rotational motions during seismic events. To avoid this rotation, structural engineers must position structural elements to keep floor eccentricity within allowable limits. This process often involves lengthy trial and error process of rearranging structural elements. To address this, CMCS desktop application tool was developed by the author. Utilizing the original concept of center of stiffness that dates back to manual rigidity analysis techniques associated with the lateral analysis of single-story shear wall buildings and C++ programing language, CMCS enables engineers to visualize and adjust the centers of mass and stiffness in real-time while also providing methods for reducing eccentricity through the provision of precise shape of shear walls. CMCS's effectiveness is demonstrated with a highly eccentric multi-story reinforced concrete building. Initial eccentricities of 35% and 43% in the 𝑥 and 𝑦 directions on the ground floor and 33% and 41% on upper floors, were reduced to 0% in both directions for all floors by following CMCS shear wall recommendations. This highlights CMCS’s potential in improving structural design and enhancing seismic resilience, offering a scientific solution to the twisting moment problem in building floors. Keywords: Seismic Design, Structural Configuration, Irregular Buildings, Centre of Mass, Centre of Stiffness, Eccentricity, Shear Walls