Volume 9 (2013): Issue 4 (December 2013)

The paper proposes a numerical model to estimate the structural behaviour of a stickbuilt glazed curtain wall system subjected to an imposed displacement of the supports in the plane of the wall. We discuss the role of the parameters that influence on the maximum inter-storey drift corresponding to the service limit state of the wall. The considered parameters are the dimensions of the glazed panel, the gap between the panel and the aluminium frame and the gap between the supports and the mullions. We discuss the problem of remnant deformation of glazed panels, and of misalignment as serviceability criteria. Comparisons are made to laboratory testing results.

The paper refers to a structural finite element analysis on the reservoirs for sludge fermentation at Glina Waste Water Treatment Plant. The purpose was to assess the dynamic response of the structure, the stress and deformation states due to the design earthquake. A linearelastic analysis was performed, according to the Romanian actual codes, in order to verify the design provisions and to emphasize the sensitivities, for a structure which was designed by analytical procedures. The results obtained on the numerical models highlight the importance of the soil-structure interaction, in peculiar the one influenced by the soil mass deformability, on the overall structural response. Based on the results of the analysis, an in-situ measurement campaign for structural dynamic characteristics was initiated, taking advantage of the ongoing repair works with subsequent exhaustion and re-filling of reservoir No. 4.

The article presents a case study on soil-structure interaction modelling for Wind turbines. After a brief presentation on the history of wind turbines and their potential in Romania, the authors take on the task of modelling the soil-structure interaction for the raft and piles. Three models are chosen: in the first model the piles are fixed at foundation depth; in the second, elastic supports are modelled on the raft and the piles and in the third model both elastic supports and fixed supports are modelled. Several comparisons are made between the three cases referring to displacements, efforts and necessary reinforcement. Based on these comparisons, the most important conclusion drawn is that the modelling of the soil-structure interaction has an important effect on the final reinforcement of the raft and the piles, considering that the difference between the models reaches almost 18%, which in the case of really large foundations can draw the line between economic and non-economic design.

At present, Romanian code for seismic design P100 is in a process of assimilation of the requirements from the equivalent European code, EN-1998-1. However, the unique characteristics of the Vrancea earthquakes require additional adjustment for some relations. One of these relations regards the simplified calculation of inelastic displacements and represents the main objective of this article. The paper uses dynamic nonlinear analysis performed on single degree of freedom systems as the main investigation tool. For all the analyses, two hysteretic models are used: Takeda and kinematic hardening. In the beginning, the paper presents the influence of overstrength on inelastic displacements for several behaviour factors. Next, the overstrength-period diagram is proposed based on a case study. Finally, the spectrum of c, the ratio between inelastic and elastic displacement is calculated. The main result of the study is the simplified equations proposed for c factor, relations that can be successfully used in current design.

A numerical study on the classical Lotka-Volterra model is performed, using approximate inertial manifolds. An analytical study consisting in the inertial form of the system is made. The construction of the approximate inertial manifolds is based on the identification of the absorbing domains using the graphical representations of the phase portraits. The hypotheses of the Jolly-Rosa-Temam algorithm are verified for certain values of parameters and the approximate inertial manifolds are constructed. Errors of approximation are computed.

Tall buildings present some specific aspects influencing the modeling and response to seismic loads. Therefore, the design rules recommended in codes, calibrated for low and medium rise buildings, are not appropriate for design of tall buildings. Other rules are needed, and performance based design represents a viable alternative for tall buildings. In this paper a methodology for the design of tall structures is proposed and it is illustrated trough a case study for a structure with perimeter tube and interior core walls, which aims to identify the particularities regarding the design, behavior and the parameters that define the post elastic behavior at the global and local level, for this structures.