The vertical acceleration response of a hypothetical footbridge is predicted for a sample of single pedestrians and a crowd of pedestrians using a probabilistic approach. This approach uses statistical distributions to account for the fact that pedestrian parameters are not identical for all pedestrians. Enhancement factors are proposed for predicting the response due to a crowd based on the predicted accelerations of a single pedestrian. The significant contribution of this work is the generation of response curves identifying enhancement factors for a range of crowd densities and synchronization levels.

Orientation of the native acetabular plane as defined by the transverse acetabular ligament (TAL) and the posterior labrum was measured intra-operatively using computer-assisted navigation in 39 hips. In order to assess the influence of alignment on impingement, the range of movement was calculated for that defined by the TAL and the posterior labrum and compared with a standard acetabular component position (abduction 45°/anteversion 15°). With respect to the registration of the plane defined by the TAL and the posterior labrum, there was moderate interobserver agreement (r = 0.64, p < 0.001) and intra-observer reproducibility (r = 0.73, p < 0.001). The mean acetabular component orientation achieved was abduction of 41° (32° to 51°) and anteversion of 18° (-1° to 36°). With respect to the Lewinnek safe zone (abduction 40° ±10°, anteversion 15° ±10°), 35 of the 39 acetabular components were within this zone. However, there was no improvement in the range of movement (p = 0.94) and no significant difference in impingement (p = 0.085). Alignment of the acetabular component with the TAL and the posterior labrum might reduce the variability of acetabular component placement in total hip replacement. However, there is only a moderate interobserver agreement and intra-observer reliability in the alignment of the acetabular component using the TAL and the posterior labrum. No reduction in impingement was found when the acetabular component was aligned with the TAL and the posterior labrum, compared with a standard acetabular component position.

In recent years several theories have been put forward in relation to lateral forces imparted on bridges from crowd movements. It is now widely accepted that the interaction between the crowd and the structure, particularly when the crowd pacing frequency is close to the lateral natural frequency, is the major factor determining the lateral response. However, very little work has been done with individual pedestrians in order to determine the relationship between the lateral force induced by a single pedestrian and the structural response. Equally, most literature concerning lateral forces induced from walking is based on results from fixed force plate tests and hence no assessment of any interaction is made.This paper examines the lateral response of a GRP (glass-fibre reinforced polymer) cable-stayed footbridge to individual pedestrian crossings at a range of pacing frequencies. Two lateral load modelling approaches are considered. The first approach, derived from back analysis of the measured bridge response, was found to be ineffective in predicting the measured response accurately. A second modelling approach, incorporating a spring-damper to represent a moving pedestrian, which thereby accounts for the interaction between the structural response and the mass, stiffness and damping characteristics of the body of the traversing pedestrian, is demonstrated to be more effective in simulating the bridge response.

The use of vegetable fibres as a sustainable alternative to non-natural sources of fibres applied for concrete reinforcement has been studied for over three decades. The main issues about plant-based fibres pointed out by other authors are the variability in their properties and concerns about potential high biodegradability in the alkaline pH of the concrete matrix. Aiming to minimise the variability of flax and hemp fibres, this research compares a range of chemical surface treatments, analysing their effects on the behaviour of the fibres and the effects of their addition to concrete. Corroborating what has been found by other authors, the treatment using NaOH 10% for 24 h was able to enhance the properties of hemp fibre-reinforced concrete and reduce the degradability in alkaline solution. For flax fibres, a novel alternative stood out: treatment using 1% of stearic acid in ethanol for 4 h. Treatment using this solution increased the tensile by 101%, causing a minor effect on the elastic modulus. Concrete mixes reinforced with the treated flax fibres presented reduced thermal conductivity and elastic modulus and increased residual tensile strength and fracture energy.

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