Theoretical Research and Shaking Table Test on Nominal Aspect Ratio of the Isolated Step-Terrace Structure

• Published in: Buildings (Basel) 2024-07, Vol.14 (7), p.2002
• Main Authors: Zhang, Longfei, Lan, Xiang, Yu, Wenzheng, Wu, Kechuan, Tao, Zhong, Wu, Zhengjia, Sun, Baifeng, Pan, Wen
• Format: Article
• Language: English
• Subjects: Aspect ratio; Bearing capacity; Bearing strength; Bearings; Compressive properties; Compressive strength; Displays (Marketing); Earthquakes; Environmental impact; Failure mechanisms; Frame structures; isolated step-terrace structure; nominal aspect ratio; Parameter identification; Rubber; Seismic activity; Seismic engineering; Seismic isolation; Seismic response; Shake table tests; shaking table test; Stiffness; Stress analysis; Structural integrity; Structural response; Tensile strength
• ISSN: 2075-5309; 2075-5309
• DOI: 10.3390/buildings14072002

With the installation of rubber isolation bearings in the upper and lower ground layers, an isolated step-terrace structure was created. Considering the ultimate bearing capacity of the rubber bearing under tension as the critical condition, a comprehensive framework was established to evaluate the overturning failure mechanisms present in isolated step-terrace structures. The bound of nominal aspect ratio was identified as the principal control index within this framework, which incorporates critical parameters such as height ratio (α), width ratio (β), vertical tensile stiffness to compressive stiffness ratio (γ), seismic coefficient (k), and nominal vertical compressive stress (σ0) to provide a thorough analysis of the structural responses and potential failure scenarios. In order to further investigate this matter, a scaled model of an isolated step-terrace concrete frame structure featuring two dropped layers and a single span within an 8° seismic fortification zone was meticulously crafted at a 1:10 similarity ratio. Subsequently, a series of shaking table tests were conducted to analyze the structural response under seismic excitation. The findings indicate that: utilizing the bound of nominal aspect ratio as a metric to gauge the anti-overturning capacity of isolated step-terrace structures is a justified approach. In instances where the height ratio remains constant, the bound of nominal aspect ratio for both positive and negative overturning trended upward with an increase in the width ratio. Notably, the bound of nominal aspect ratio for positive overturning consistently registered lower values compared to that of the negative overturning, underscoring the heightened susceptibility of step-terrace structures to positive overturning. Moreover, in scenarios characterized by higher height and width ratios, the structural integrity remained unscathed by any overturning effects arising from insufficient tensile strength in rubber bearings. Furthermore, the bound of nominal aspect ratio exhibited an ascending trend as the seismic coefficient, nominal vertical compressive stress, and vertical tensile stiffness to compressive stiffness ratio decreased. The outcomes derived from the shaking table test not only confirm the impressive seismic performance of the structure, but also, by closely examining the instantaneous stress variations within the upper and lower isolation layers of the model, substantiate the existence of a positive overturning hazard in