Tsunamis are unpredictable and infrequent but potentially large impact natural disasters. To prepare, mitigate and prevent losses from tsunamis, probabilistic hazard and risk analysis methods have been developed and have proved useful. However, large gaps and uncertainties still exist and many steps in the assessment methods lack information, theoretical foundation, or commonly accepted methods. Moreover, applied methods have very different levels of maturity, from already advanced probabilistic tsunami hazard analysis for earthquake sources, to less mature probabilistic risk analysis. In this review we give an overview of the current state of probabilistic tsunami hazard and risk analysis. Identifying research gaps, we offer suggestions for future research directions. An extensive literature list allows for branching into diverse aspects of this scientific approach.

This paper presents ultra-low cycle fatigue tests and the calibration of different fracture models for duplex stainless steel devices of high seismic performance braced frames. Two different geometries of the devices were tested in full-scale under fourteen cyclic loading protocols up to fracture. The imposed protocols comprised of standard, constant amplitude, and randomly-generated loading histories. The test results show that the devices have stable hysteresis, high post-yield stiffness, and large energy dissipation and fracture capacities. Following the tests, two micromechanics-based models, i.e. the Cyclic Void Growth Model and the built-in Abaqus ductile fracture model, were calibrated using monotonic and cyclic tests on circumferentially-notched coupons and complementary finite element simulations. In addition, Coffin-Manson-like relationships were fitted to the results of the constant amplitude tests of the devices and the Palmgren-Miner's rule was used to predict fracture of the devices under the randomly generated loading protocols. Comparisons of the experimental and numerical results show that the calibrated models can predict ductile fracture of the devices due to ultra-low cycle fatigue with acceptable accuracy.

No abstract

Keywords: Dual seismic-resistant steel frame; low-damage steel frame; residual drift mitigation; energy-dissipative brace; replaceable fuse; nonlinear finite element analysis. Abstract.A dual seismic-resistant steel frame, which consists of a moment-resisting frame equipped with high post-yield stiffness energy-dissipative braces, is proposed and numerically evaluated. Replaceable hourglass shape pins made of duplex stainless steel with high postyield stiffness and large energy dissipation and fracture capacity are in series connected to conventional steel braces. Moreover, replaceable fuses are introduced in the beams at the locations where plastic hinges are expected to develop. A performance-based seismic design procedure and appropriate capacity design rules are used to design the dual frame, while its seismic performance is evaluated with advanced numerical simulations using experimentally validated shell-solid finite element models and simplified beam element models. The numerical results show that the dual frame has adequate stiffness and energy dissipation capacity to control peak storey drifts (i.e. non-structural damage), while plastic deformations (i.e. structural damage) are isolated within the replaceable pins of the braces and the beam fuses. In addition, the high post-yield stiffness of the pins, combined with the appreciable elastic deformation capacity of the moment-resisting frame, results in significant reduction of residual storey drifts, which are found to have a mean value of 0.06% under the design earthquake and a mean value of 0.12% under the maximum considered earthquake. These values indicate a superior residual storey drift performance compared to steel frames equipped with buckling restrained braces, and highlight the potential of the proposed dual frame to help steel buildings to return to service within an acceptable short time in the aftermath of a strong earthquake.2

Summary This paper presents a comprehensive comparison of different dynamic and static approaches for assessing building performance under sequential earthquakes and tsunami. A 10‐storey reinforced concrete seismically designed Japanese vertical evacuation structure is adopted as a case study for the investigation. The case study building is first assessed under sequential earthquake and tsunami nonlinear response history analyses: the first time this is done in the literature. The resulting engineering demand parameters are then compared with those obtained when the analysis procedure is systematically simplified by substituting different static approaches for the nonlinear response history analyses in both the earthquake and tsunami loading phases. Different unloading approaches are also tested for the cases when an earthquake pushover is adopted. The results show that an earthquake nonlinear response history analysis, followed by a transient free vibration and a tsunami variable depth pushover, provides the best alternative to full dynamic analyses in terms of accuracy and computational efficiency. This structural analysis combination is recommended and has the advantage that it does not require the tsunami inundation time history to be known in advance. The proposed double pushover approach is instead deemed only suitable for the collapse assessment of regular low to mid‐rise buildings and for the development of collapse fragility functions. An important observation made is that sustained earthquake damage seems not to affect the tsunami resistance of the case study building when the fully dynamic analysis is carried out for the sequential loading. This observation will be the subject of future work.