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Typically, the columns of the prefabricated reinforced concrete (RC) industrial buildings and warehouses with large clear storey heights are very slender, with aspect ratios (shear span to width) larger than 10. In addition to supporting the gravity loads, the columns also provide strength, stiffness, dissipation and displacement capacity of the primary lateral-load resisting system. However, current empirical relationships that predict the non-linear response and failure mechanisms of RC columns have been developed mainly for lower aspect ratios (< 7), typical of ordinary multi-storey buildings or short-to-medium bridge piers. What makes slender columns different is their predominant flexural response, larger drifts at nominal strength and corresponding lower ductility demands, smaller ratios between the strain penetration and plastic hinge lengths to the element shear span and risk of P-Delta instability. Therefore, the direct application of analytical models available in the literature to slender columns poses a risk of overestimation of their deformation and dissipative capacity. In turns this could lead to the underestimation of their displacement demand, overall damage and collapse probability of the primary seismic-resisting and load-bearing system. In the present research extensive analysis on the non-linear response of slender columns was performed based on observed post-earthquake damage to buildings in Italy and Turkey, experimental data and numerical predictions of the failure patterns through non-linear fiber element models. The influence of the foundation flexibility and the presence of industrial floor was also investigated. The outcome is a simplified analytical methodology for the prediction of the non-linear force–deformation response and possible failure mechanisms of slender precast columns due to rebar buckling or P-Delta effects, as a fundamental step towards the seismic assessment of the global structural performance and cost-efficient retrofit solutions for precast concrete industrial buildings. [ABSTRACT FROM AUTHOR]

Field observations following the May 2012 Emilia, Italy, earthquakes have revealed the seismic vulnerability of storage steel tanks typical of the past Italian design practice, highlighting structural deficiencies observed during previous events in other areas and mostly related to lack of structural seismic design and detailing, lack of redundancy, and inadequate anchorage design and execution. Damage was disproportionately high, considering the moderate size of the events (MW = 6.11 and MW = 5.96 on 20th and 29th May, respectively). Failure modes observed are reported and classified. Comparison is provided with the results of high-definition finite element (FE) dynamic simulations, performed on tanks representative of those inspected. Numerical analyses, accounting for material and geometrical nonlinearities, at the element level, as well as for fluid-structure interaction through highly nonlinear methods, were able to capture the stress/strain concentrations that caused them to collapse. Elephant's foot and diamond buckling induced by hydrodynamic pressures as a result of inertial forces imparted during the earthquakes were reproduced, as well as shear-buckling failure of leg-supported tanks or sliding of unanchored systems. [ABSTRACT FROM AUTHOR]

Abstract: Layered limestones with marly–clayey interbeds are widespread in mountain regions. Where tectonics has not changed the original structure they frequently form homocline slopes, that since the last deglaciation have evolved through planar block slides along bedding joints. A typical dip slope showing this evolution is represented by the left flank of the Adige River valley south of Rovereto (North-Eastern Italy). Even though layers never daylight at the slope toe, the exceptional persistence and weakness of bedding joints allows buckling of layers, which occasionally collapse causing rock avalanches. Before monitoring started, deformations were believed to be no longer active, this conviction being strengthened by the high safety factors provided by limit equilibrium analyses. SAR satellite interferometry performed between 1990 and 2002 and probe inclinometer measures indicate that the slabs located uphill from the buckle folds are slowly sliding. Since some doubts have been raised about rock mass behaviour, slope geometry and hydraulic conditions assumed in the analyses, buckling was back-analysed using the Distinct Element Method (DEM) and the Discontinuous Deformation Analysis (DDA). These treat the rock mass as a discontinuum and account for deformation and failure of the rock material. To perform numerical analyses, rock mass structure, strength and stiffness were determined through extensive in situ and laboratory investigations. For this purpose field surveys, borehole core logging and geophysical surveys were performed and laboratory geotechnical tests on the rock material, clayey interbeds and bedding joints were conducted. Discontinuous analyses confirmed that buckling deformations are definitely possible if some conditions are present (high water pressure, minor flexures). Modelling also indicate that buckling deformations may evolve into failures and should therefore be taken into account in evaluating long term stability of the slope. [Copyright &y& Elsevier]