Cost-effective analysis technique for the design of bridges against strike-slip faulting

The paper studies the performance of a typical overpass bridge, with continuous deck and monolithic pier-deck connections, subjected to strike-slip faulting. A three-dimensional (3D) finite element (FE) model of the entire bridge–foundation–abutment–soil system is developed, accounting for soil, structure and geometric nonlinearities. Soil behaviour is simulated with a thoroughly validated strain softening constitutive model. The concrete damaged plasticity (CDP) model is implemented for piers, accounting for the interaction between axial force N , bending moment M , shear force Q and torsion T (NMQT ); the model is validated against experimental results from the literature. The location of the fault rupture is parametrically investigated, confirming the vulnerability of indeterminate structural systems to large tectonic deformation. The deck is shown to sustain both in-plane and out-of-plane bending moments, as well as torsion; the piers are subjected to biaxial bending, shear and torsion. The response is highly dependent on the location of the fault rupture, emphasizing the need to develop cost-effective modelling techniques. Four such techniques are developed (with and without decoupling) and comparatively assessed using the detailed 3D FE model as benchmark. The best prediction is achieved by a coupled model, which includes the bridge superstructure, detailed 3D modelling of the soil-foundation system only for the pier directly affected by the fault, and nonlinear springs representing the foundations of all other piers. The proposed technique offers a computationally efficient means to parametrically analyse long multispan bridges subjected to faulting, for which full 3D FE modelling is impractical.     

Significance of boulder shape,shoreline configuration and pre-transport setting for the transport of boulders by tsunamis

Research on tsunami-induced coarse-clast transport is a field of rising interest since such deposits have been identified as useful proxies for extreme-wave events (tsunamis, storm waves) that provide crucial information for coastal hazard assessment. Physical experiments are, beside in-situ observations, the foundation of our understanding of how boulders are transported by tsunamis and provide clues to the development of empirical equations and numerical models describing the processes and fundamental mechanics. Nevertheless, investigating tsunami-induced boulder transport is a comparatively young discipline and only a few experimental studies focusing on this topic have been published so far. To improve the knowledge on nearshore tsunami hydrodynamics, physical experiments utilizing real-world boulder shapes have been carried out simulating three different shore types in a wave flume. Crucial insights were gained into boulder transport hydrodynamics and data resulting from the experiments were analysed in an empirical, statistical, quantitative and qualitative manner. The regular cuboid boulder – one of the specific shapes used in the experiments – showed the longest transport distances compared to a complex, natural boulder and a flat cuboid boulder, but also significant fluctuations regarding the total transport distance. The experiments indicate a strong influence of the shore shape on boulder transport behaviour. Experimental setups of increased mean transport distances also led to a higher spreading of results. This spreading was further amplified between the idealized-shaped cuboid and the complex-shaped boulder, which is associated with a lower drag coefficient. Due to the highly sensitive boulder reaction to divergent experimental setups, the need to recognize boundary conditions overcoming commonly considered parameters (e.g. roughness or Flatness Index) in field studies and numerical models is underlined. Beside the strong influence of initial boulder submergence and alignment, both the boulder shape and shore type influence the boulder transport pattern, increasing the total transport distance by more than 350% in some cases. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

On singularities in electrodynamics and gravitational theory

The singularity and particle problems in electrodynamics and gravitational theory are discussed. Comparing different modifications of MAXWELL 's electrodynamics and general theory of relativity, arguments are given which show possibilities of solving these problems by a modification that replaces EINSTEIN 's equations by those of the EINSTEIN -BACH -WEYL -type.     

WUIVAC: a wildland-urban interface evacuation trigger model applied in strategic wildfire scenarios

An evacuation trigger is a point on the landscape that, once crossed by a wildfire, triggers an evacuation for a community. The Wildland-Urban Interface Evacuation (WUIVAC) model can be used to create evacuation trigger buffers around a community using fuels, weather, and topographic inputs. A strategic, community-scale application of WUIVAC for the town of Julian, California was investigated. Eight years of wind measurements were used to determine the worst-case (strongest) winds in 16 directions. Surface fire rate of spread was used to calculate evacuation trigger buffers for the communities of Julian and nearby Whispering Pines, and for three potential evacuation routes. Multiple trigger buffers were combined to create fire planning areas, and trigger buffers that predict the closure of all evacuation routes were explored. WUIVAC trigger buffers offer several potential benefits for strategic evacuation planning, including determination of when to evacuate and locating potential evacuation routes.     

Human Losses Expected in Himalayan Earthquakes

Quantitative estimates of potential losses that may be caused by future great earthquakes along the Himalaya suggest that as many as 150,000 people may die, 300,000 may be injured and typically 3,000 settlements will be affected in a single event. Scenario results used here vary and are based on ruptures of 150 km segments of the plate boundary at seven positions, where sufficient elastic energy is believed to be stored for magnitude eight earthquakes. The method of calculating these results was calibrated, using the 17 disastrous Indian earthquakes, which have occurred since 1980. About 50 settlements in the region are considered most at risk because in each more than 2000 fatalities may occur.     

Electromagnetic induction fields in the deep ocean north-east of Hawaii: implications for mantle conductivity and source fields

Summary. We have analysed a thirty-six day recording of the natural electric and magnetic field variations obtained on the deep ocean floor north-east of Hawaii. The electromagnetic fields are dominated by tides which have an appreciable oceanic component, especially in the east electric and north magnetic components. The techniques of data analysis included singular value decomposition (SVD) to remove uncorrelated noise. There are three degrees of freedom in the data set for periods longer than five hours, indicating a correlation of the vertical magnetic field and the horizontal components, suggesting source field inhomogeneity. Tensor response functions were calculated using spectral band averaging with both SVD and least squares techniques and rotated to the principal direction. One diagonal component, determined mainly by the north electric and east magnetic fields, is not interpretable as a one-dimensional induction phenomenon. The other diagonal term of the response function indicates a rapid rise in conductivity to 0.05 mho m⁻¹ near 160 km. No decrease in conductivity below this depth is resolvable. Polarization analysis of the magnetic field indicates moving source fields with a wavelength near 5000 km. Model studies suggest that the two dimensionality in the response function may be caused by motion in the ionospheric current system.     

Sulfur dioxide and other cloud-related gases as the source of the microwave opacity of the middle atmosphere of Venus

Spacecraft radio occultation measurements imply the presence of a nonuniformly mixed gaseous absorber within, but mostly below, the main cloud layer of sulfuric acid—water droplets measured by Pioneer-Venus. Preliminary considerations of the amount, distribution, and effects of sulfur dioxide and other gases, which apparently are associated with and produce the cloud, indicate that they constitute an important, and probably the predominant, source of the observed microwave opacity of the middle atmosphere of Venus.     

On the origin of spicules in the chromosphere-corona transition region

Qualitative arguments are presented to show that in the chromosphere-corona transition region the energy which is transported downwards by heat conduction cannot be disposed of by radiative losses only. The region therefore is unstable and forced to be in motion, which may give rise to spicule-like phenomena.On leave from the Observatory Sonnenborgh at Utrecht, The Netherlands.