Structural Behavior of Interlocking Load Bearing Hollow Block Wall Panels With Stiffeners Under In-Plane Vertical and Lateral Loads

An experimental study was conducted at the Universiti Putra Malaysia to investigate the effect of stiffeners on the structural behavior of Putra interlocking load bearing hollow block wall panels under vertical and lateral loadings. Putra block building system, developed by the Housing Research Centre of Universiti Putra Malaysia, consists of three types of blocks namely stretcher, corner and half blocks. Six wall panels each with 0.9 m width, 1.0 m height and 0.15 m thickness were tested. These wall panels were divided into two sets, each containing three specimens, one with no stiffener and the other two were stiffened with 2 and 3 steel bars and cement grout respectively. The steel bars were placed along the perimeter of the wall panels. All test specimens were subjected to in-plane loading. For vertical load test, uniformly distributed vertical load was applied from zero until failure. In lateral load test, a constant vertical load was applied on the top of the wall, while in-plane lateral load was applied from zero until failure. The effect of stiffeners was investigated by comparing important parameters such as; vertical deflection as well as in-plane and out of plane lateral deflections, failure loads and failure patterns between the stiffened and un-stiffened wall panels. To evaluate the resistances of the wall panels with different stiffeners, strength, cracks pattern and deformation were recorded and analyzed. The results show a significant increase in strength capacity associated with reduction in both lateral and vertical deflections for the stiffened wall panels. In addition, there was reduction in the in-plane lateral deflection for wall panels under the effect of lateral load. A significant change in crack pattern and failure mechanism was also observed. Compressive strength and shear strength for wall panels under the effect of vertical and lateral load which stiffened with 2 and 3 reinforcement steel bars were increased as compared with un-stiffened wall panel. The compressive strength was increased by 21% and 33% for wall panels stiffened with 2 and 3 reinforcement bars respectively as compared with un-stiffened wall panel. And, the shear strength was increased by 50% and 68.7% for wall panels stiffened with 2 and 3 reinforcement bars respectively as compared with un-stiffened wall panel

Field behavior of a high anchored reinforced earth wall

Since the invention of Reinforced Earth by the French architect Hendri Vidal in 1966, numerous reinforced soil walls have been designed and constructed all over the world. In this study the focus was on a particular type of reinforced wall called Nehemiah wall which differed from the Vidal type in the sense that instead of steel strips, the reinforcing elements consisted of steel bars with anchor blocks attached at the free ends. A full scale high anchored reinforced earth wall was constructed and instrumented to capture the essential behavior of the wall. Two sections of the wall were monitored where at one of the sections polystyrene foam was inserted at the back face of the wall panel to allow for lateral deformation to take place which means that the facing was less flexible in the transverse direction. The lateral deformation, axial forces along the reinforcing bars and settlement were monitored and measured for both cases and the results were compared and discussed

Cryogenic wind tunnels: Problems of continuous operation at low temperatures

The design of a cryogenic wind tunnel which operates continuously, and is capable of attaining transonic speeds at generating pressures of about 3 bars is described. Its stainless steel construction with inside insulation allows for very rapid temperature variations promoted by rapid changes in the liquid nitrogen flow. A comparative study of temperature measuring probes shows a good reliability of thin sheet thermocouples. To measure fluctuations, only a cold wire makes it possible to record frequencies of about 300 Hz. The use of an integral computer method makes it possible to determine the impact of the wall temperature ratio to the adiabatic wall temperature for the various parameters characterizing the boundary layer. These cases are processed with positive and negative pressure gradients

Pool boiling in microgravity with a single specie system

Pool boiling experiments in microgravity on the small copper plate of 1cm² have been performed in the SOURCE 2 experiment aboard the sounding Rocket Maser 12 launched on February 13th, 2012. The SOURCE 2 experiment is a small-scale tank devoted to the study of heat and mass transfers with a liquid refrigerant HFE7000 pressurised with its vapour. SOURCE 2 (SOUnding Rocket Compere Experiment) was developed in the frame of a French German space programme COMPERE (on the behaviour of propellant in launcher tanks) managed by CNES and DLR and a MAP ESA Project "Multiscale Analysis of boiling". During the 6 minutes of the flight different physical phenomena were studied by our partners: ZARM, University of Bremen, Air Liquide and Astrium. The boiling experiment was performed in a 6 cm diameter and 28 cm long cylindrical tank partly filled with a refrigerant Novec HFE7000 with a low boiling point (34°C at 1 bar) and pressurized by its own vapour. The heating element used for the boiling investigation consisted of an electrical resistance heated by Joule effect in contact with a flux-meter and a copper plate with a thickness of 40 micrometres. The flux-meter was equipped with two thermocouples. It was then possible to measure at the same time the heat flux transmitted to the liquid and the wall temperature. The liquid temperature above the heater was measured by 5 micro thermocouples located in the vicinity of the wall. Images of the boiling phenomenon were recorded by a video camera through the transparent cylindrical wall of the tank. SOURCE 2 is in the continuity of the SOURCE 1 experiment, which flew successfully on Maser 11 on 15 May 2008 (Kannengieser et al. 2010). The experiment scenario was similar to the present case. However, in SOURCE 1, liquid HFE-7000 was pressurized by gaseous nitrogen. The lateral glass wall was preheated and a strong evaporation took place at the free surface in the vicinity of the wall. Due to the presence of nitrogen a strong Marangoni convection occurred at the free surface enhancing nitrogen dissolution in the liquid phase. Then during the boiling experiment, the bubble growth was due to liquid vaporization and nitrogen desorption. Marangoni convection also occurred at the bubble interface leading to a capillary force pushing the bubble to the heated wall. In the SOURCE 2 experiment, a single specie configuration is studied (liquid/vapour HFE7000). This changes the thermo-hydraulic behaviour of the system. Since no Marangoni convection kept the bubble in contact with the heated wall, a primary bubble detached and grew by feeding itself with the smaller bubbles formed over the heated surface. The change in the bubble size is only due to vaporization. Then the measurements of the heat flux transferred to the fluid by the heater could be directly correlated to the amount of vapour production (balance of evaporation and re-condensation) that could be evaluated from visualization and image processing. When the rocket was launched, the test cell was empty. The top part and the lateral glass wall of the test cell were preheated before launch. Just before the microgravity period, the tank filling began, liquid HFE7000 at 25 °C was injected in the tank by the pump and pressurized by hot vapour HFE7000. At the beginning of the boiling experiment, the tank pressure was reduced to 1.5 bars and the heating of the heater element was switch on and boiling started. During this period, it was planed to study boiling with high sub-cooled liquid then to decrease the pressure to 1 bar to study saturated boiling. However while pressurization with hot vapour HFE7000, strong condensation occurred that rapidly warmed up HFE7000 up to 40°C during boiling study. As a consequence, at 1.5 bars, the sub-cooling was limited to 5 degrees. Then the tank pressured was reduced to 1.3 bars to investigated boiling in saturated conditions. On the other hand, before launch, tests were performed on ground and boiling curves were plotted. In this paper we will attend to compare the results obtained in micro-gravity and in 1G

Bond Strength Tests Between Silicon Wafers and Duran Tubes (Fusion Bonded Fluidic Interconnects)

The fusion bond strength of glass tubes with standard silicon wafers is presented. Experiments with plain silicon wafers and those coated with silicon oxide and silicon nitride are presented. Results obtained are discussed in terms of homogeneity and strength of fusion bond. High pressure testing shows that the bond strength is large enough for most applications of fluidic interconnects. The bond strength for 525 /spl mu/m thick silicon with glass tubes having outer diameter of 6 mm and with wall thickness 2 mm, is more than 60 bars after annealing at a temperature of 800/spl deg/C

Soft-wall induced structure and dynamics of partially confined supercritical fluids

The interplay between the structure and dynamics of partially confined Lennard Jones (LJ) fluids, deep into the supercritical phase, is studied over a wide range of densities in the context of the Frenkel line (FL), which separates rigid liquidlike and non-rigid gaslike regimes in the phase diagram of the supercritical fluids. Extensive molecular dynamics simulations carried out at the two ends of the FL (P = 5000 bars, T = 300 K, and T = 1500 K) reveal intriguing features in supercritical fluids as a function of stiffness of the partially confining atomistic walls. The liquidlike regime of a LJ fluid (P = 5000 bars, T = 300 K), mimicking argon, partially confined between walls separated by 10 {\AA} along the z-axis, and otherwise unconstrained, reveals amorphous and liquidlike structural signatures in the radial distribution function parallel to the walls and enhanced self-diffusion as the wall stiffness is decreased. In sharp contrast, in the gas-like regime (P = 5000 bars, T = 1500 K), soft walls lead to increasing structural order hindering self-diffusion. Furthermore, the correlations between the structure and self-diffusion are found to be well captured by excess entropy. The rich behavior shown by supercritical fluids under partial confinement, even with simple interatomic potentials, is found to be fairly independent of hydrophilicity and hydrophobicity. The study identifies persisting sub-diffusive features over intermediate time scales, emerging from the strong interplay between density and confinement, to dictate the evolution and stabilization of structures. It is anticipated that these results may help gain a better understanding of the behavior of partially confined complex fluids found in nature

Influence of boundary conditions on the behavior of an anchored reinforced earth wall

The finite element model is used to simulate the behavior of the full scale instrumented anchored reinforced wall. The validated finite element model is then used to carry out parametric studies to ascertain the influence of the boundary conditions on the behavior of the wall. The boundaries at the crest, facing and base of the wall are varied to study their effects. At the crest of the wall, slope surcharge of various geometrical dimensions are imposed. At the facing of the wall, the boundary is allowed to yield laterally by inserting a compressible geoinclusion at the back face of the wall panels. Meanwhile, at the base, the boundary is allowed to yield vertically by allowing the wall to sit on a compressible foundation soil. The behavior of the wall is determined in terms of the tensile stress distribution developed in the reinforcing bars, the summation of the maximum tension in the reinforcing bars, the summation of the tensions developed at the connection to the facing panels, the lateral movement at the facing and the vertical movement at the base

Lifting A Weight Off My Shoulders

It’s a familiar scene for anyone who’s entered the Jaeger Center. You walk past the entrance desk, past the rock wall, the blue mats with some students stretching; there, the cardio machines, some soccer players cycling on the bikes, some girls on the elliptical machines and scattered on the treadmills, a guy on the stairmaster, a teacher jogging. Finally, you reach the end, the huge space filled with free weights, barbells, a leg press machine, and some pull up bars. You pay attention less to the selection of weights then who occupies this space: men, lots of them. At any time of day or night, you can find several male students working out here. What’s much less common, one might even say rare, is to see women in this space. Certainly, there are some of us, particularly in groups or entering with a sports team. But the ratio is uneven, to say the least. [excerpt

Guide for users of the National Transonic Facility

The National Transonic Facility (NTF) is a fan-driven, closed-circuit, continuous flow, pressurized wind tunnel. The test section is 2.5 m x 2.5 m and 7.62 m long with a slotted-wall configuration. The NTF will have a Mach number range from 0.2 to 1.2, with Reynolds number up to 120 10 to the sixth power at Mach 1 (based on a reference length of 0.25 m). The pressure range for the facility will be from 1 to about 9 bars (1 ban = 100 kPa), and the temperature can be varied from 340 to 78 K. This report provides potential users of the NTF with the information required for preliminary planning to test programs and for preliminary layout of models and model supports which may be used in such programs