This study was conducted to study the redistribution of internal force and the development of the plastic hinge of an MBS with foundations at two different elevations considering the torsional effect. The results indicate that the redistribution of the base shear of MBS is evident at different embedding ends, and the redistribution of story shear on different floors also took place. The redistribution of the shear force of columns is different at the upper- and lower-embedding sides, and the internal force redistribution is more prominent along the slope direction. Consequently, the redistribution of the internal force of MBS should be considered in practical seismic design. Furthermore, the damage of MBS is transferred from the floors above the upper-embedding end to the floors under the upper-embedding end with the increase in the seismic intensity, where the elements at the floors above the upper-embedding end suffer the most serious damage, and the damage is unevenly distributed in the upper-embedding story and the adjacent upper story. The lower-embedding column is more prone to hinge across the slope direction because of the torsional effect. With γintra changes, the redistributions of the shear force of the base, story, and column are different. A larger γintra would result in a weaker redistribution of base shear. The redistribution of the story shear of the 1st floor and its columns along the slope direction shows an increasing-decreasing tendency with the increase in γintra, and the redistribution is the most serious when γintra is 0.4. While across the slope direction, the redistribution of the story shear tends to be weakened as γintra increases. The forming of the plastic hinge of single-frames along the slope direction is related to γintra and γnon, especially the damage of the upper-embedding columns. The torsional effect has a significant influence on the damage of the single-frames across the slope direction. Some measures should be taken to improve the bearing capacity of the upper embedding columns and columns on floors under the upper-embedding end, as well as the drift ductility of the upper-embedding columns.

One of key issues of designing connected structure is the design of the connecting body between towers. This paper presents the analysis of different connecting body design schemes based on a 202.15 m (663 ft) twin-tower ultra-high-rise structure connected by a connecting truss. The influence of height and type of connection on the entire building structure was studied by comparing storey shear forces and drift of structure. The results indicated that the connection type between the connecting body and main structure has little influence on the building structure performance. Finite element analysis of the connecting body indicated that the internal force characteristic of rigid connection type is better compared to the hinge connection type. Furthermore, the connecting truss design based on inclined braces connected by hinge joint is superior compared to the rigid joints.

Split-foundation (SF) building structures, as a kind of hill-side buildings, are widely used in mountainous regions due to the scarcity of plain areas. In order to experimentally investigate the seismic responses of the SF structure, shaking table test was carried out on two 1/8-scale models: a split-foundation RC frame structure supported by foundations at two different levels and a conventional RC frame structure supported by foundations at one single level. The failure patterns, dynamic characteristics, acceleration responses, displacement responses, and torsion responses of the two models were assessed and compared under seismic ground motions. The test results indicate that the two models were severely damaged after the last intensity level excitation and showed an intermediate failure mechanism. The damage to the SF model was uneven and special with relatively severe damage of the upper grounded columns. The difference in natural frequencies between the two models resulted from the effect of the lower story on lateral stiffness, and the effect was relatively dramatic in the transverse direction. The difference in structural stiffness led to larger acceleration amplification factors of the SF model and smaller acceleration amplification factors in the longitudinal direction. Although the restriction at upper ground level created a certain effect on displacement responses of the SF model especially in the first story, the curve shapes of displacement responses of the two models were similar from the first floor to fourth floor. In addition, the torsion responses of the SF model, especially in the first story (upper ground story), were obviously much larger than those of the conventional model. The torsional effect cannot be ignored in the SF structure which is a torsionally sensitive structure.

Frame structures supported by foundations with different elevations (such as a structure on the slope) undergo different ground motions because of the local site effect. Seismic response of the structure under non-uniform excitation of ground motion is different from that under uniform excitation on upper embedding end or lower embedding end. Sites with the same height difference and different soil conditions were set up in this paper to subject them to ground motions related to different positions and the seismic response of structures built on the sites under uniform and non-uniform strong seismic excitation were compared. The results show that the predominant period and amplitude of ground motions on upper embedding end and lower embedding end are different and affected by soil conditions. The extent and law of amplification of shear force, displacement and storey drift of structures under non-uniform excitation differ from those under uniform excitation when soil changes from soft to medium-hard soil. In addition, the position and degree of plastic hinges change under non-uniform excitation compared to uniform excitation. The uniform excitation using the ground motion on the upper embedding end is not always safe for the frame structure supported by foundations at different elevations.