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Recent destructions of structures due to insufficient isolator deformation capacity have led to demands for greater seismic redundancy in seismic isolation design. For a friction pendulum system (FPS), the effect of bidirectional behavior of earthquakes on the maximum response and its effect on friction heating, temperature, and in turn on the maximum response can be significant. However, the extent of these effects under different FPS design parameters and different types of ground motions (GMs) is still not clear. In this study, an analytical model of double concave FPS considering the coupling effect of friction heating and bidirectional behavior was proposed and validated by bidirectional earthquake response orbits, which reflect the characteristics of both GMs and FPSs. Then, the effects of bidirectional GM and corresponding bidirectional temperature change on the response were investigated under different types of strong GMs. Finally, a performance‐based design method with a bidirectional‐effect‐compensation mechanism was proposed. For double concave friction pendulum bearings with PTFE‐related layers, it was found that the bidirectional behavior of earthquakes will amplify the maximum isolator displacement by an average of 110–210% (60 MPa) and the maximum superstructure acceleration by an average of 100–140% (60 MPa) under strong GMs (PGV‐C1 > 0.2 m/s) and optimum design parameters. The amplification ratio is not only influenced by GM characteristics but also highly related to the design parameters and friction‐heating effect of DCFPS. [ABSTRACT FROM AUTHOR]

The reliability of friction dependencies under real earthquakes has rarely been validated and the effect of the velocity and temperature increase caused by bidirectional excitation on the maximum displacement remains unclear. In this study, friction dependencies were validated using full-scale dynamic tests under earthquake response orbits, and their contribution to the maximum displacement was assessed under strong ground motions. In general, friction dependencies are still applicable to real earthquakes. Moreover, the effect of velocity increase can be ignored, but the effect of temperature increase on displacement is significant, particularly under ground motions with large magnitudes and small distances to faults. [ABSTRACT FROM AUTHOR]

To establish a practical method to detect damage to autoclaved lightweight concrete (ALC) exterior walls subjected to earthquakes, a cyclic loading test of steel structural frames equipped with ALC exterior walls was performed. In the test, several compact and cost-effective MEMS accelerometers were placed on the ALC panels and steel structural frames to evaluate their effectiveness in damage assessment. The results showed that the MEMS acceleration sensors could measure the residual in-plane and out-of-plane rotation angle of each element including ALC panels with sufficient accuracy and was concluded to be the most promising instrument for application to damage detection. [ABSTRACT FROM AUTHOR]

Practical cumulative damage evaluation methods are essential for commercializing metallic dampers, such as U-shaped steel dampers. The high dependence on numerical simulations, such as time-history analysis, significantly restricts the use of the previously reported cumulative damage evaluation method in the quick inspection of U-shaped steel dampers. This makes simplifying and efficiently certifying the estimated value of cumulative damage difficult. Therefore, the precision verification approach of the previously reported damage evaluation method and quick inspection method are combined in this study based on the change in the shape of the dampers caused by dynamic cyclic loading. [ABSTRACT FROM AUTHOR]

The damage caused by small inelastic loadings cannot be neglected when the number of cycles is large. Previous research has mainly focused on the low cycle fatigue (LCF) behaviors of beam-to-column connections, ignoring those of columns. Here, cyclic loading tests were conducted on 22 cold-roll-formed square hollow section columns under multiple small-amplitude loadings. All the specimens failed owing to flange fracture. The effects of the axial force ratio, shear span ratio, and loading amplitude on the LCF behaviors were investigated. Fatigue life prediction methods were developed, and two methods for predicting the lateral resistance deterioration of the specimens were proposed. [ABSTRACT FROM AUTHOR]