SPT-Based Evaluation of Soil Liquefaction Risk

The city of Catania in Sicily (Italy) been destroyed in the past by the 1169 earthquake with XI MCS intensity, the 1693 earthquake with X MCS intensity and the 1818 earthquake with VIII MCS intensity. The standard approach for the evaluation of the liquefaction susceptibility is based on the estimation of a safety factor between the cyclic shear resistance to liquefaction and the earthquake induced shear stress. The liquefaction potential index has been evaluated in the area of the Catania port, near Saint Giuseppe La Rena, that experienced liquefaction because of the 1693 and 1818 earthquake. The site under study has been characterized by means of boreholes, in situ and laboratory tests. Liquefaction susceptibility has been evaluated by means of a procedure prescribed by the new Italian Code

Analysis of the Behavior of the Piled Foundations of a Group of Earthquake Damaged Buildings

The Sicilian earthquake of 13th December, 1990 was not very strong, but it caused considerable damages on structures, included a group of reinforced concrete buildings located in Augusta town on the east coast of Sicily (Italy). To evaluate the possibility to repair these buildings, an investigation on soil, structures and foundations was carried out. As some buildings were founded on piles, load tests on piles of the piled foundations were carried out. The site was well investigated by means of laboratory and in-situ tests including: standard penetration tests, cone penetration tests, dilatometer tests and seismic tests. To evaluate dynamic stress-strain geotechnical characteristics of soils resonant column tests were also performed. In the paper the experimental results of the load tests are analyzed with the aim to study the behavior of the piles subject to additional seismic loads. Load tests showed that the seismic actions have not damaged the effectiveness of the soil-pile system, as the bearing capacity of the piles appeared unchanged in spite of the additional loads applied on the structures during the earthquake. Nevertheless because the existing piled foundations were enable to carry on the additional horizontal seismic forces, a few number of piles were added

Continuous Monitoring of Transmission Lines Sag through Angular Measurements Performed with Wireless Sensors

High voltage transmission lines are crucial infrastructure that are demanded to supply an increasing request of electric energy. In the design and operations stages, sag represents a key parameter which must respect specific constraints. Therefore, sag continuous monitoring is becoming essential to guarantee the correct functioning of the line and to optimize the current flow. Different solutions have been proposed in literature, but they are still lacking efficiency and reliability to be used during operations. In this work, a simple and efficient method, based on conductor parabolic approximation, is developed and used to compute the sag through the measurement of the conductor slope in proximity of the span extremities. The angular measurements are obtained using wireless sensors equipped with MEMS accelerometers developed by authors and employed for HVTL conductor vibration monitoring. The proposed method and its implementation in the monitoring system was tested in a laboratory environment on a real conductor. The values of sag at different tensile loads have been obtained and compared to the measured ones, with satisfactory results according to the accelerometer resolution. The solution developed therefore represents a complete and innovative tool to be adopted in the field to monitor, in real time, both the sag and the level of vibration due to the wind action, allowing to increase the performance reliability of HVTL

Experimental and Numerical Analysis of the Behaviour of an Embankment Stabilized with Vertical Drains

The paper deals with the settlement analysis of an embankment founded on soft soil and realized for the construction of a reinforced concrete building in the industrial area of Catania (Sicily, Italy). The solution adopted consisted in the construction of the embankment by stages with thirty-three vertical prefabricated drains disposed under the embankment. Soil consolidation settlements took place since the beginning of the embankment construction. The experimental measurements were carried out since August 2000 up to January 2001. The site was well investigated by means of in-situ and laboratory tests. A significantly correspondence between the values of the geotechnical parameters derived from laboratory and in situ tests was observed. Consolidation was investigated and a comparison between computed results and field measurement is presented. The future performance of the embankment is predicted and the end of consolidation has been estimated in terms of settlements, which must be considered of major interest for the evaluation of the stability of the overlying structure

A Simplified Approach for the Evaluation of Kinematic Pile Bending

There are two sources of loading of the pile by the earthquake: “inertial” loading of the pile head caused by the lateral forces imposed on the superstructure, and “kinematic” loading along the length of the pile caused by the lateral soil movements developed during the earthquake. Seismic codes prescribe that piles have to be designed for soil deformations arising from the passage of seismic waves which impose curvatures and thereby lateral strains on the piles along their whole length. Accepting these lines, the new Italian seismic normative (NTC, 2008) specify that kinematic effects should be taken into account in the design of pile foundations. Pseudo-static approaches for the seismic analysis of pile foundations are attractive for practicing engineers because they are simple when compared to difficult and more complex dynamic analyses. Thus, in the paper a simplified numerical model for the analysis of the behavior of a single pile subjected to static loadings and/or to lateral soil movements based on the “p-y” subgrade reaction method has been adopted. The approach involves two main steps: first a free-field site response analysis is carried out to obtain the soil displacements along the pile; next a static load analysis is carried out for the pile subjected to the maximum free-field soil displacements at each node along its length and the static loading at the pile head based on the maximum ground surface acceleration

Optimal Design and Control of 4-IWD Electric Vehicles based on a 14-DOF Vehicle Model

A 4-independent wheel driving (4-IWD) electric vehicle has distinctive advantages with both enhanced dynamic and energy efficiency performances since this configuration provides more flexibilities from both the design and control aspects. However, it is difficult to achieve the optimal performances of a 4-IWD electric vehicle with conventional design and control approaches. This work is dedicated to investigating the vehicular optimal design and control approaches, with a 4-IWD electric race car aiming at minimizing the lap time on a given circuit as a case study. A 14-DOF vehicle model that can fully evaluate the influences of the unsprung mass is developed based on Lagrangian dynamics. The 14-DOF vehicle model implemented with the reprogrammed Magic Formula tire model and a time-efficient suspension model supports metric operations and parallel computing, which can dramatically improve the computational efficiency. The optimal design and control problems with design parameters of the motor, transmission, mass center, anti-roll bar and the suspension of the race car are successively formulated. The formulated problems are subsequently solved by directly transcribing the original problems into large scale nonlinear optimization problems based on trapezoidal approach. The influences of the mounting positions of the propulsion system, the mass and inertia of the unsprung masses, the anti-roll bars and suspensions on the lap time are analyzed and compared quantitatively. Some interesting findings that are different from the `already known facts' are presented