A Characterization Method for Pavement Structural Condition Assessment based on the Distribution Parameter of the Vehicle Vibration Signal

A pavement structural survey plays a vital role in road maintenance and management. This study was intended to explore the feasibility of a non-stop pavement structure assessment method by analyzing the vibration data from a vehicle sensor. In this study, three falling weight deflectometer (FWD) tests and four vehicle vibration tests were conducted on five pavement structures. The FWD test results show that the continuously reinforced composite pavement has a higher structural stiffness than the semi-rigid base asphalt pavement. According to the statistical distribution of vehicle acceleration, a distribution parameter, the peak probability density (PPD), was proposed. The correlation coefficient (−0.722) of the center deflection (D1) and PPD indicates a strong correlation between the two variables. Therefore, PPD is strongly correlated with pavement structural stiffness. This study proposed a novel characterization method for pavement structural conditions based on the distribution parameter of the vehicle vibration signal.

A method of forming a spacecraft adapter layout to meet the requirements of dynamic compatibility by topological and parametric optimization methods

At present, the developers of launch vehicles impose a requirement for dynamic compatibility of the spacecraft with the launch vehicle, which consists in limiting the lower boundary of the first transverse and first longitudinal fundamental (primary) frequencies of the natural vibrations of the spacecraft fitted with an adapter of relatively rigid base. One of the tasks that must be solved in order to meet this requirement is the development of the spacecraft adapter layout. The traditional process of designing the adapter consists in developing its design on the basis of analogues and carrying out verification analysis with subsequent refinement of the design to meet the strength and stiffness requirements. However, this approach takes a lot of time and is not adaptable to constant changes in the input data at the initial design stage. The article presents a technique allowing the adapter layout to be quickly designed. The layout is determined to a greater extent by calculations using the topological and parametric optimization methods. The application of the developed technique is shown on the example of the development of an adapter for a promising spacecraft. It should be applied in the early stages of design. The results obtained by the method should be used as input data and recommendations for the design of the adapter.

Evolution of the Seismic Response of Monopile-Supported Offshore Wind Turbines of Increasing Size from 5 to 15 MW including Dynamic Soil-Structure Interaction

As a result of wind power’s expansion over the globe, offshore wind turbines (OWTs) are being projected in seismic prone areas. In parallel, the industry develops increasingly larger and more powerful generators. Many of the seismic response analyses of wind turbines conducted so far only consider smaller units. In this paper, a finite element substructuring model in frequency domain is used to compute the seismic response of four reference OWTs from 5 to 15 MW founded on monopiles embedded in several homogeneous soil profiles with shear wave velocities from 100 to 300 m/s and subjected to different accelerograms. The foundation behaviour is obtained through a continuum model including kinematic and inertial interaction. The relevance of soil-structure interaction and main trends of the seismic response of OWTs are inferred from the presented results. Although the seismic maximum bending moments increase with the size of the OWT system, their relevance with respect to the ones produced by design loads decreases as the turbine gets bigger. The same effect is observed for the shear forces if the soil is soft enough. The inclusion of SSI effects almost duplicates the seismic response when compared to the rigid base scenario.

Analysis of G+5 Storeys Building With and Without Floating Column

In current period, several structures are being planned and built with structural complicatedness like building with floating columns on different floors and spaces. The buildings accompanying floating columns are extremely detrimental that is constructed in earthquake-prone regions. The current study analyses and compare the buildings with and without of floating column. The columns which are directly supported by a beam without any rigid base are known as floating columns. Various buildings have been constructed with floating columns in India. Typically, it is required to provide larger spacing between the columns to entertain the requirements of parking or reception lobbies. Some of the functional requirements of a building might be satisfied by providing the floating columns but the structural behaviour of the building changes abruptly. The beams that supported the floating columns require more flexure and shear demand than the surrounding beams. In addition, it leads to stiffness unevenness at a specific joint. Columns are the main structural elements that resist the lateral load in a rigid frame and have the importance in the performance of the building under earthquake load The storey’s stuffiness below the floating column is normally reduced. Therefore, an attempt has been made to analyse the performance of a G+5 storey building with and without floating columns and compare structural parameters such as horizontal displacement, storey drift and storey shear under seismic excitation using (ETABS) Software.