Laterally accreted deposits in low efficiency turbidites associated with a structurally-induced topography (Oligocene Molare Group, Tertiary Piedmont Basin, NW Italy)

ABSTRACT The origin of laterally accreted deposits in ancient deep marine successions is often controversial. Indeed, not always do these features imply the occurrence of meanders or high-sinuosity turbidite channels, but they can be generated by other causes, such as sediment-gravity-flow dynamics controlled by the morphology of tectonically confined mini-basins. This work discusses laterally accreted deposits composed of sharp-based, normally graded beds in a very small tectonically controlled mini-basin. These beds, characterized by a well-defined asymmetrical cross-current facies tract, form well-developed lateral-accretion surfaces dipping in directions ranging between W and SW, and perpendicular to the paleocurrents directed towards the N. For this reason, these deposits have always been interpreted as point bars related to meandering channels. A new detailed stratigraphic framework and facies analysis have led to an alternative interpretation, namely that these deposits record lateral deflections of small volume, longitudinally segregated turbidite dense flows against a structurally controlled morphological high. This interpretation is also supported by a comparison to other tectonically controlled turbidite systems that are characterized by higher degrees of efficiency but show similar laterally accreted deposits and cross-current facies tracts.

Does Self-Compacting Concrete Exert more Pressure on Formworks than Normal Vibrated Flowing Concrete?

This paper investigates lateral pressure on formwork indirectly by measuring lateral deflection using an innovative device. This device is fabricated from Polyvinyl Chloride (PVC) cylindrical mold in a fashion allowing occurrence and measurement of lateral movement at different depths using dial gauges. The lateral deflections for different systems of filling materials including water, sand, self-compacting concrete (SCC), and flowing concrete. The flowing concrete is tested under two conditions, vibrated (NVC), and non-vibrated (NCno.V). The results show that the NVC produced the largest lateral deflection which attributed to the vibration pressure. The measured lateral deflection are ranked descending in the following order: NVC, Water, SCC, NCno.V and Sand.

TORSIONAL STIFFNESS AS AN INFLUENCE PARAMETER ON ARCH STABILITY

Arch bridge springs can be connected to concrete abutments either by prestressing bars or by connectors. In both options, the torsional stiffness is substantially reduced, compared to the full arch cross sectional area. The influence of this lack of torsional stiffness on arch buckling is being researched, both numerically and experimentally. To reduce any residual stress during tests, wooden rods that simulate the arch were submerged in water and subsequently bent to the desired shape. Imperfections of the arch samples are measured. Two unequal concentrated loads are applied to the samples, thus simulating the effect of movable loads across half of the arch span. During loading, lateral deflections were measured until elastic buckling occurred. The simulation of more flexible rotation of the springs required replacing the cross section by thin equivalent side plates. Since all parameters have not been isolated, the results are limited yet. However, comparing the failure load of similar conditions, the reduction of torsion stiffness by 81.48% reduces the failure load by 26.3%. This indicates that total prevention of axial rotation may not be imperative for arch bridges.

Influence of Surface Properties on Soccer Ball Trajectories

In this paper, we summarize our recent research work on soccer balls. Employing wind tunnels and analyses of simulated trajectories, we have gained an understanding of how various surface features influence soccer ball aerodynamics. Wind tunnels provide aerodynamic coefficients for non-spinning soccer balls. The coefficients then help determine the trajectories of various simulated kicked balls. Surface features include panel texturing, seam width, and seam depth. We have determined that small changes in surface texturing can lead to hard-kicked soccer balls experiencing lateral deflections as large as 10%–20% of their horizontal ranges. We have also found that the critical Reynolds number for soccer balls is more strongly correlated with seam width than with seam depth.

Effect of a soccer ball’s seam geometry on its aerodynamics and trajectory

Five different soccer balls, each possessing the traditional 32-panel surface design, were tested in a wind tunnel. Only seam depth and width varied between the balls. Wind-tunnel tests and an examination of correlation revealed that seam width with a linear fit [Formula: see text] and [Formula: see text] was a stronger indicator of a ball’s critical speed than seam depth. Wind-tunnel data were used for computational modeling of many soccer-ball trajectories. It was determined that variations in seam geometry resulted in fluctuations up to 4 m in the horizontal range of hard-hit, no-spin kicks that travel approximately 68 m. Those seam geometry variations also contributed to lateral deflections up to 4 m for the aforementioned hard-hit, no-spin kicks.

Null effect of scratches made by curling rocks

There is disagreement in the literature as to whether scratches made by curling rocks affect the motion of subsequent curling rocks. The aim of this investigation is to provide unequivocal experimental evidence to resolve this disagreement. Such evidence has been obtained by comparing the curl distances (total lateral deflections) of rocks sliding over ice with no scratches to curl distances of rocks sliding over ice completely covered with scratches made by previous curling rocks. The result of this simple experiment is that there is no appreciable difference in the curl distances between the two ice conditions. The conclusion is that the scratches made by curling rocks do not affect the motion of other curling rocks and that the lateral deflection of curling rocks cannot solely be due to scratches made by curling rocks.

Wind-Induced Fatigue and Asymmetric Damage in a Timber Bridge

The transformation of a 30 m long timber pedestrian bridge into a wobbly (laterally swaying) bridge with a dramatically reduced first lateral modal frequency has been monitored by seven annual, multi-sensor surveys. This evidence, in combination with analysis of the wind record, observations of local damage and evidence of wind-induced excitations from other bridges, is used to present a multi-stage scenario of the extraordinary structural weakening of our study bridge in only a few years. Our analysis is constrained by observations of asymmetric damage (longitudinal splitting cracks around metallic connections along the south side of the deck, not explained by ordinary, essentially symmetric lateral oscillations) and over-threshold analysis of strong northerly wind events, including gusts. The proposed scenario is that an unexpected for the area icing event took advantage of construction vicissitudes and produced damage that reduced the lateral stiffness of the bridge, especially of the arch superstructure. In addition, strong winds sharing common direction with gusts produced a combination of semi-static lateral bending and of dynamic oscillations, leading to numerous cycles of asymmetric high amplitude lateral deflections producing tensile stress normal to grain, cracks localized in connections, and fatigue. The vertical stiffness of the bridge was only slightly affected.

Calculation Approach for Lateral Bearing Capacity of Single Precast Concrete Piles with Improved Soil Surrounds

Precast concrete (PC) piles with cement-improved soil surrounds have been widely used for soft ground improvement. However, very few calculation approaches have been proposed to predict the lateral bearing capacity. This study aims at investigating the lateral capacity of a single PC pile reinforced with cement-improved soil through a series of 3D finite element analyses and theoretical studies. It is revealed that application of cement-improved soil around the PC pile can obviously reduce the induced lateral deflections and bending moments in the pile and can significantly increase its capacity to resist lateral loading. To account for the reinforcement effect of cement-treated soil, a modified m approach is proposed by introducing a modified coefficient to enable the predictions of the lateral bearing capacity for such reinforced PC piles. It is revealed that the modified coefficient is approximately linearly related to the compressive bearing capacity of improved soil surrounds.