Volume 11 (2015): Issue 3 (September 2015)

The subject discussed in this paper is based on an experimental bridge model which was built to study the pre-critical and post-critical buckling behaviour of steel webs of box girders provided with longitudinal and transversal stiffeners. The article presents a comparison between the experimental results and the numerical ones for buckling resistance of stiffened steel webs. For this purpose two types of analysis will be carried out: an analysis to establish the values and eigenvectors of buckling, after which the critical factor for the first mode of buckling will be obtained, and then a geometrical and physical nonlinear analysis will be performed.

This paper presents two simplified analytical methods to analyze lock gates submitted to two different accidental loads. The case of an impact involving a vessel is first investigated. In this situation, the resistance of the struck gate is evaluated by assuming a local and a global deforming mode. The super-element method is used in the first case, while an equivalent beam model is simultaneously introduced to capture the overall bending motion of the structure. The second accidental load considered in this paper is the seismic action, for which an analytical method is presented to evaluate the total hydrodynamic pressure applied on a lock gate during an earthquake, due account being taken of the fluid-structure interaction. For each of these two actions, numerical validations are presented and the analytical results are compared to finite-element solutions.

The paper presents the results of a numerical program that was used to investigate the seismic performance of dual steel frames with dissipative shear walls. Nonlinear static and dynamic analyses were employed in order to evaluate the global ductility and the q factor for a twelve story building. The influence of the q factor on the estimated level of damage and post-earthquake intervention strategy was investigated. The dynamic analyses were conducted using two groups of accelerograms, selected to match the response spectra of two types of grounds. The numerical models were validated against experimental tests. The results show that q factor values adopted in design influence the level of damage. If re-centering capacity is properly controlled by design, the replacement of damaged walls can minimize the time and cost of intervention, thus supporting disaster resilience of buildings

To obtain the coordinates by means of precise point positioning (PPP) technique we need to use the undifferenced GPS pseudocode and carrier phase observations but to obtain the “precise” positioning we need precise orbit and clock data too. This products and other information for obtaining the results by using PPP technique on a centimeter level accuracy can be downloaded from different locations, but the most reliable satellite ephemerides and clock correction are available from International GNSS Service (IGS).

In the PPP analysis we determined the parameters such as the receiver clock error, ionospheric delays code biases, code multipath and the total neutral atmosphere delay of the observations. For the determination of the permanent station coordinates, using the PPP technique, we used precise orbit and clock solutions to enable absolute positioning of a single receiver.

In this article we present the results obtained by using the PPP technique on the permanent station Oradea, from which we can conclude that the PPP technique can be used for different GNSS application.

Seismic vulnerability for a structure represents the susceptibility to be affected by an event with a given intensity. The vulnerability of a structure can be influenced by the design methods or by different problems that may appear during the execution process.

This paper shows a case study for the vulnerability increase of a reinforced concrete frame structure in 2 different situations:

a) modification produced due to code changes, meaning P100-2006 respectively P100-2013;

b) modifications produced the structure taking into account the errors which have occurred during the execution process;

For both cases, capacity curves were plotted considering the nonlinear analysis, also called pushover. The numerical simulation was performed in SAP2000 software. These curves were compared with the response spectrum corresponding to the site conditions in order to obtain the performance point. For accurate results, fragility curves were plotted for both considered situations, according to previous research of the authors.

The paper emphasizes the importance of each stage during the execution of a structure. More over the differences in the vulnerability index show the importance on the overall behavior of the structure. Solution to increase strength and safety for the structure are also given at the end of the paper