SummaryHigh‐rise buildings are an efficient solution to meet the housing challenges of global urbanization that is happening at an incredible pace. Code‐based seismic design philosophies are aimed at achieving collapse‐prevention under major earthquakes, implying extensive structural damage associated with important losses. A number of high‐performance systems have been investigated for enhancing the resilience of high‐rise buildings whose design is especially challenging due to higher‐mode effects even when a flexural mechanism is formed at the base of the structure. To this end, this paper proposes a new concept consisting of a three‐dimensional uncoupled rocking and shear mechanism system for high‐rise buildings where reinforced concrete (RC) core walls are used as the lateral‐force‐resisting system. The proposed system provides a dual‐mechanism at the base that independently limits both overturning moments (OTMs) and shear forces and thus more effectively mitigates higher‐mode effects. The characteristic mechanics of the proposed system are first studied through an idealized model. A physical embodiment is then designed, detailed, and validated through advanced models and extensive nonlinear dynamic analyses. A 42‐story RC core‐wall building that is located in Los Angeles and was studied as part of the PEER Tall Buildings Initiative is used as a reference structure in this study. Results confirmed that the proposed system eliminates damage at the base of the walls and minimizes the inelastic demands over the height of the building. In a general sense, the proposed concept provides a framework in which the intended dual mechanism can be implemented to a wider range of high‐rise structures.

In general, clayey soils exhibit more or less both creep and swelling. In this paper, “creep” means viscous compression under a constant load condition in an oedometer test, while “swelling” means viscous expansion under a constant load condition in an oedometer test and is a reverse behaviour to creep for all saturated soils. Clayey soils containing the clay mineral montmorillonite show strong creep and swelling characteristics. Both creep and swelling characteristics have a significant influence on the deformation and failure of geotechnical structures. This paper presents main data from tests on a mixture of bentonite–silica sand in one-dimensional (1D) straining. Tests include (i) multistaged loading tests with unloading–reloading and enough time for creep and swelling in 1D straining and (ii) step-changed constant rate of strain (CRSN) compression tests with unloading–reloading in 1D straining as well. From the test data, the creep, swelling, and strain rate effects are observed and discussed. Based on the test data and a 1D elastic viscoplastic (1D EVP) model developed by Yin and Graham (1989, 1994 ), the authors propose a new 1D elastic viscoplastic model considering both creep and swelling (called 1D EVPS). The data from the multistage oedometer tests are used to calibrate the new model. After this, the new model is used to simulate the step-changed CRSN compression tests and make a comparison. In this way, the new model is verified. The new 1D EVPS is then used to simulate CRSN tests with a single strain rate, relaxation in the creep or swelling region, and constant rate of stressing tests. It is found that the new model can simulate well the strain (or stress) rate effects, loops in unloading–reloading, and stress relaxation in the creep region or stress increase in the swelling region, which are all caused by both creep and swelling of the soil.

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The finite element method has been employed to study the effects of different boundary conditions on the axial buckling of multiwall carbon nanotubes ͑MWCNTs͒. Unlike previous works, both homogeneous and heterogeneous end constraints are considered for the constituent tubes of various MWCNTs comprising shell-type ͑i.e., the length-to-diameter ratio L / D Ͻ 10͒, beam-type ͑i.e., L / D Ͼ 10͒, and the two different types of constituent tubes. The results show that clamping the individual tubes of simply supported or free MWCNTs exerts a variety of influences on their buckling behaviors depending on the type of the MWCNTs, the position, and the number of the clamped tubes. Clamping the outermost tube can enhance the critical buckling strain up to four times of its original value and can shift the buckling modes of those MWCNTs consisting both shelland beam-type tubes. In contrast, little difference can be observed when simply supported ends of MWCNTs are replaced by free ends or vice versa. Explicit buckling mode shapes obtained using the finite element method for various physically realistic cases have been shown in the paper.