Innovative devices for the protection of welded sections in steel structures

The paper proposes the use of innovative devices devoted to the brittle collapse protection of welded steel sections, typically represented by the end beam cross-sections in framed structures. Reference is made to I-shaped cross-sections. At first, limiting to the case of plane stress, the relevant elastic domain is defined in the NN, TT, MM space; then a plane frame equipped with the proposed devices and subjected to seismic load condition is studied, ensuring that the generalized stresses at the welded sections be within the relevant elastic domain

Probabilistic Evaluation of the Adaptation Time for Structures under Seismic Loads

In this paper, a probabilistic approach for the evaluation of the adaptation time for elastic perfectly plastic frames is proposed. The considered load history acting on the structure is defined as a suitable combination of quasi-statical loads and seismic actions. The proposed approach utilizes the Monte Carlo method in order to generate a suitable large number of seismic acceleration histories and for each one the related load combination is defined. Furthermore, for each load combination the related adaptation time is determined, if any, as the optimal one for which the structure is able to shakedown under the unamplified applied actions. A known generalized Ceradini's theorem is utilized. The adaptation time values obtained with reference to all the generated seismic acceleration histories for which the shakedown occurs allows us to define the related cumulative conditioned probability function and, therefore, to identify the optimal adaptation time as the one with a probability not lower than a suitably assigned value

'R&D and export performance: exploring heterogeneity along the export intensity distribution'

This study analyses the relationship between firm-level innovative effort as measured by R&D expenditures and export intensity. We apply quantile regression techniques to a sample of Italian firms to verify whether R&D expenditures’ effect varies along the conditional distribution of export intensity, after controlling for censoring and endogeneity issues. Empirical findings suggest that the effect of R&D expenditures on export intensity is positive and that firms taking most advantage from R&D activity are in the right tail of the export intensity distribution (from the 70th quantile onwards), that is, those exporting 50% of their sales or more. Overall, the results prove robust to several specification checks and suggest not only that firms’ innovative efforts help explaining heterogeneity in export intensity performance, but also that its positive effect differs across the export to sales ratio distribution. This implies that innovation policy measures might be more effective for firms characterised by a relatively high export intensive margin

Experimental analysis of "bovedas tabicadas"

A particular type of vaulted structures, known as b\uf3vedas tabicadas (Catalan vaults), made with alternate layers of bricks and mortar and characterized by a very low thickness in comparison to the other two dimensions, are studied. The research has been faced under the historical aspect as well as under the mechanical one, developing experimental and numerical analysis regarding real existing structures. In particular, the experimental analysis, performed by effecting compression and bending tests on samples taken from a real structure, has been devoted to the constitutive material identification and the characterization is made by considering the material as an ideal homogeneous; further experimental tests have been made on a real vault and the related numerical analyses have been developed by utilizing a suitable FEM discretization

On the structural optimization in presence of base isolating devices

The minimum volume design of plane frames constituted by elastic perfectly plastic material and subjected to appropriate combinations of fixed, cyclic and dynamic loads is studied. The influence on the design, in terms of cost (volume) and behavioural features, of seismic protecting devices is particularly focused. The considered protecting device is a lead rubber bearing base isolation system. Two optimal design problem formulations are proposed for the structure with or without the protecting device, both based on the so-called statical approach. The minimum volume frame is reached accounting for three different resistance limits: the purely elastic limit, the (elastic) shakedown limit and the instantaneous collapse limit. The adopted load combinations are alternatively characterized by the presence of only fixed loads, of amplified fixed loads and quasi-static perfect cyclic loads due to the wind action, of suitably reduced fixed loads and dynamic actions due to the earthquake. The linear elastic effects of the dynamic actions are studied by utilizing a modal technique. Reference is made to the most recent Italian code related to the structural analysis and design. The solution of the optimization problem is reached by using a suitable subroutine available into the optimization toolbox of MATLAB\uae appropriate to the proposed formulations. A flexural frame is studied with and without the relevant seismic protecting device in order to study the influence on the design of such a base isolation system. The related minimum volume structures are obtained assuming the stiffness and the damping feature of the base isolation system as variables within assigned suitable ranges. The Bree diagrams of the obtained optimal designs are also determined in order to characterize and compare their structural and safety behaviou

How local is local? Evidence from bank competition and corporate innovation in U.S.

This paper aims to fill in a research gap in the effects of bank competition on corporate innovation. In addition to the evidence on the favorable effects of bank competition on corporate innovation, we show novel evidence on the substitution effects of bank competition in a wider region and neighbor-state to local bank competition in financing corporate innovation activities. In banking market, we show ‘how local is local’ depends on the operating scope and information transparency of firms. Local banks have an information advantage over distant banks in financing local businesses and informationally opaque corporate innovation activities