THE EFFECT OF STEP-HEIGHT ON THE KNEE ANGLES AND IN-SHOE PRESSURE DISTRIBUTIONS DURING STEP-AEROBICS

INTRODUCTION A recent trend in indoor exercise is step-aerobics. This form of aerobic exercise involves the rhythmic stepping up to and down from a fixed platform to the beat of the accompanying "pop" music. In the past, substantial research has been done on the kinematics of the climbing of actual architectural stairs (Andriacchi et al., 1980; McFayden and Winter, 1988; Laubenthal et al., 1972) but no studies, to date, have been done to explore the kinematics of this new fitness phenomenon. Therefore, the purpose of this investigation was to study the biomechanics of step aerobics. Specifically, the effect of the step-height on the knee angles and in-shoe pressure distributions of subjects performing step aerobics was evaluated. It was hoped that the results of this study could be used to help determine any possible biomechanical health concerns of participation in step aerobics

Moods of 3-Week and 5-Week Outdoor Expedition Participants

The purpose of this research project was to investigate and document the cycle of mood states displayed by outdoor recreation expedition participants. It was hypothesized that an individual\u27s moods pass through a predictable cycle during the beginning, middle, and end phases of a 3-week to 5-week outdoor expedition.This cycle would include fluctuations in mood states such as anger/hostility, confusion/bewilderment, de­pression/dejection, fatigue, tension/anxiety, and vigor. It was anticipated that ten­sion/anxiety would be high in the beginning, medium to high in the middle, and then low at the end. Depression/dejection was ex­pected to be low in the beginning, high in the middle, and medium to low at the end. Anger/hostility was hypothesized to low in the beginning, high in the middle, and low at the end. Vigor/activity was anticipated to be high in the beginning, low in the middle, and high at the end. It was expected that fa­tigue/inertia would be high in the beginning, low in the middle, and then medium to low at the end. Finally, confusion/bewilderment was predicted to be high in the beginning, then I.ow in the middle and end

Effects of 2012 Earthquake on the behavior of Ghirlandina tower in Modena

Collapse events, that occurred in the past (such as the Venice Bell Tower in 1902 and the Civic Tower in Pavia in 1989) claimed for the need to assess the long-term behavior of such monuments. A significant effort has been therefore devoted to clarify the reasons for these collapses after many centuries from the construction date. In addition, recent earthquakes in Italy have once again put into evidence the seismic vulnerability of the cultural heritage. To assess this aspect, in many cases the soil-structure interaction cannot be neglected. In this context, a simple but consistent framework for soil-structure interaction analysis is here presented with reference to a case history. It is discussed how the difference in the fundamental frequency observed during seismic events can be associated to non-linearity in soil response, leading to a rotational stiffness of the soil-foundation system consistent with the shear strain level derived from the seismic ground response analysis. Thereafter, the validated soil-structure interaction model has been used to define an equivalent SDOF model of the structure that explains the differential settlements suffered by the Ghirlandina tower in Modena during the 2012 seismic events as well as its behavior since those events

Dynamic Response of Cantilever Retaining Walls Considering Soil Non-Linearity

For many decades the analysis of earth retaining structures under dynamic or seismic conditions has been carried out by means of standard limit equilibrium (Coulomb, M-O) or elastic methods (Wood, Veletsos and Younan). These approaches are simplified, as they make use of considerable approximations which are often applicable only under particular conditions. A different and perhaps more realistic approach is possible using established computer codes, which integrate numerically the governing equations of the soil and wall media. Since these problems may involve significant levels of strain in the backfill, material non-linearity should be taken into account to realistically simulate the response of the system. In the herein-reported study, a parametric analysis is carried out through the finite-difference code FLAC 5.0. Starting from simple cases involving elastic response, and moving gradually towards more realistic conditions, salient features of the dynamic wall-soil interaction problem are addressed. The case of non-linear hysteretic behaviour of soil and flexibility of wall is considered at a second stage. Results indicate that with increasing levels of acceleration, there is a clear transition from elastic behaviour (in which the aforementioned V-Y type methods are applicable), to plastic behaviour in which M-O methods are thought to be more suitable under pseudo-static conditions. The results of the parametric analyses are reported in terms of pertinent normalized parameters, to provide a general framework for the assessment of wall-soil dynamic interaction under strong seismic excitation

Numerical modelling of wave attenuation through soil

Numerical analyses of induced ground vibrations play an important role in assessing building safety and comfort. One of the major difficulties is related to the calibration of an adequate source model to be used in the numerical simulation. In this paper the attenua-tion of waves caused by drop load tests is considered to provide a general framework for the evaluation of vibration attenuation both with empirical laws and numerical simulations. A new equation to reproduce the source signal is suggested and used as input for a dynamic cou-pled consolidation Finite Element Analysis. The model is validated through comparison with field data obtained at a site in the vicinity of the Tower of Pisa, Italy, from geophones at various distances from the impact source. The calibrated numerical model is then used to study in detail the attenuation of waves from the source and assess the validity of empirical attenuation laws

Laterally constrained inversion of surface wave data at Najaf city (Iraq)

A case history is reported to outline a possible strategy for the construction of a pseudo-2D model of shear-wave velocity for seismic site response studies. Experimental data have been collected using the Multichannel Analysis of Surface Wave technique (MASW) at six sites in the city of Najaf (Southern Iraq). The sites are aligned along the route of a proposed subway. The dataset has been processed to extract the dispersion curves of each site and then it has been inverted by using a Laterally Constrained Inversion (LCI) algorithm. The initial model for the local search algorithm has been obtained with a preliminary Monte Carlo Inversion (MCI). A priori information from borehole logs and lateral constraints between neighbors 1D models are used to mitigate the non-uniqueness of the solution. The result is a pseudo-2D shear-wave velocity model of the area which is in good agreement with sediment lithology and thicknesses obtained from borehole log