Complexity‐reduced in the hydroclimatological modelling of aquifer's discharge

Climate variability induces considerable interannual fluctuations in spring discharge, especially in mountain areas, where groundwater is recharged mainly by rain and snow melt. This study presents the discharge climatological model (DISCLIM), which was developed to test a complexity‐reduced approach to perform historical reconstruction in the lack of physical assumptions. The Mount Cervialto aquifer (Southern Italy) is the test site, where a powerful karst spring is monitored since the 1920s and is very sensitive to climatic conditions. DISCLIM incorporates seasonal precipitation and climate indicators only. Despite its simplicity, DISCLIM has been able to well estimate the yearly fluctuations of discharge hydrological, explaining about 90% of the interannual variability at the calibration stage, and more than 80% at validation stage. This means that DISCLIM can be easily used for estimating the discharge in historical times, when no all the hydrological balance data are available for the purpose.     

Dynamic increase factor for pushdown analysis of seismically designed steel moment-resisting frames

The independent threat scenario of sudden column loss under localised damage is usually considered in progressive collapse assessment. The effect of the sudden removal of a column is like the sudden application of the gravity load on the structure when significant deformations occur. This conventional approach is based on the simplifying but realistic hypothesis that the peak dynamic response can be assessed with reasonable accuracy using the nonlinear static response. In this approach, amplified gravity loads are applied to the bays that are affected by the removed column to compensate for the dynamic effects corresponding to the real load redistribution. The paper investigates the dynamic increase factor to be considered in the nonlinear pushdown analysis of seismically designed steel moment-resisting frames. The influence of the fundamental parameters involved in progressive collapse analysis was highlighted. The effect of various design variables, such as the number of stories, the number of bays, the location of the removed column and the level of seismic design load was investigated. The dynamic increase factor was estimated in a way to generate the best match of the peak dynamic responses through the nonlinear static analysis. Finally, the values obtained were expressed as a function of the vertical displacement at the location of the removed column and then compared with the GSA formulation based on the ductility factor.     

Behaviour Factor of code-designed steel moment-resisting frames

Current seismic codes are based on force-controlled design or capacity design, using the base shear concept. The most important parameter in this approach is the response modification factor, also called behaviour factor, which is used to design the structure at the ultimate limit state by taking into account its capacity to dissipate energy by means of plastic deformations. In this paper overstrength, redundancy and ductility response modification factors of steel moment resisting frames are evaluated. In order to cover a wide range of structural characteristics, 12 steel moment-resisting frames (6 regular and 6 irregular in elevation) have been designed and analysed. Both static pushover analyses and nonlinear incremental dynamic analyses have been performed. The investigation focuses on the effects of some parameters influencing the responsemodification factor, including the regularity, the number of spans and the number of storeys. As a conclusion, a local ductility criterion has been proposed to improve the provisions given in the Italian seismic code.     

Space–time prediction of rainfall-induced shallow landslides through a combined probabilistic/deterministic approach,optimized for initial water table conditions

In landslide-prone areas the magnitude of events is related to recurring rainfall intensity. In a large sector of the Sannio Apennines (Southern Italy), predictive mapping of recurrent shallow landslides was undertaken by combining deterministic and probabilistic predictive approaches. This, with the aim to minimize the negative influence of the uniform distribution of the initial water table depth in steady condition that usually influence the theoretical instability resulting from the application of methods for large-scale estimation. The deterministic approach was performed by means of the Transient Rainfall Infiltration and Grid-based Regional Slope-stability model to obtain triggering maps in multi-temporal transient pore-water pressures. The optimized physical modeling was validated by back-analysis on large-magnitude landslide events which occurred in 2003 by means of the introduction of two cross-mapping correlation indexes. Subsequently, different predictive scenarios were proposed for different probabilistic return periods of the rainstorm events. The output data permitted the definition of a linear log regression curve to estimate the theoretical instability of the study area. This curve is defined as a function of cumulative precipitation, duration and return periods of the possible rainfall events.