Mitigation of Tsunami Debris Impact on Reinforced Concrete Buildings by Fender Structures

Buildings located in coastal regions are prone to tsunami dangers, which often carry debris in the form of shipping containers and boats. This paper presents an approach for the design of fender structures to minimize debris impacts on buildings. The impact of shipping containers, which are categorized as large debris, is considered in the study. Since the weights of shipping containers are standardized, the impact energy can be related to other debris. For a fender structure, cone-type rubber fenders are used to resist the impact of the shipping container. Various fender reactions are considered as parameters to study the efficiency of the fenders. The displacement-controlled nonlinear static analysis is carried out to determine the building capacity. The energy approach for shipping container impact is used to evaluate the resistance of the building. Capacity curves, energy absorptions, inter-story drift ratios of the buildings with and without a fender structure, and the efficiency of the fender are presented. The buildings with a fender structure can absorb the energy from the impact of a loaded shipping container. Conversely, the building without a fender structure cannot resist the impact of a loaded shipping container. From the obtained results, a recommendation is given for buildings with a fender structure. The hydrodynamic force on the fender structure is transferred to the main building through the fender. Hence, the yield force of the fenders affects the performance of the main building that must be considered in the design.

The effect of mesocarbon microbeads on magnetorheological fluid behavior

Magnetorheological (MR) fluids are composed of magnetizeable particles suspended in a carrier fluid and change apparent viscosity upon the application of a magnetic field. Previous studies have shown that passive particles, such as hollow glass spheres, can augment the yield stress of MR fluids, but this yield stress augmentation has limited endurance because the hollow glass microspheres are not sufficiently durable. This study evaluates mesocarbon microbeads (MCMBs) as an alternative passive particle with the potential for MR yield force augmentation but with greater durability. The yield properties of six MR fluid concentrations with varying carbonyl iron particle (CIP) and MCMB volume fractions were tested using a shear mode rheometer and flow mode MR damper. MCMBs did not augment yield stress in shear mode, but, in contrast, in flow mode, the yield force increased nonlinearly with MCMB volume fraction. Furthermore, this yield force-enhancing effect did not diminish over 100,000 cycles (or 5 km of piston travel). The theoretical non-dimensional plug thickness which arises from an approximate parallel plate analysis of a fluid element in flow mode is used illustrate to a potential mechanism for the yield force augmentation effect.

Mechanical Behaviour of Unshelled Moringa oleifera Seeds at Varying Moisture Contents

The determination of mechanical properties of unshelled Moringa oleifera seeds was studied under compression test at varying orientations and moisture contents for postharvest equipment design. A completely randomized block design (CRBD) was applied in designing the experiment. The impact of varying moisture content levels of (10.25, 17.33, 24.47, and 32.34% dry basis) on the applied force at bio-yield and rupture, deformation, energy at rupture, crushing strength, and elastic modulus of the seed samples were investigated. Polynomial functions of the 2nd order with coefficients of correlation ranging between 0.642 ≤ R2 ≤ 0.999 gave the best fit and described the resulting relationships between the studied properties with respect to moisture levels at the two loading axes. Results obtained showed that the seed samples had maximum values of 80.3 N, 110 N and 257.2 J, for bio-yield force, rupture and rupture energy respectively at (10.25% d.b., in the horizontal orientation; whereas minimum values of 31.5 N, 54.9 N and 51.3 J for bio-yield force, rupture force and rupture energy occurred at (32.34% d.b.) respectively in the vertical orientation. Also, the maximum compressive strength of 5.8 N mm-2 in the horizontal orientation of the seed samples at 10.25% d.b. whereas the minimum compressive strength (2.5 N mm-2) occurred in the vertical orientation at 10.25% d.b. moisture content. The sample exhibited less resistive strength to crushing in the horizontal position as the moisture increased; whereas in the vertical position, the cell’s vertical edges provide some form of shield against external pressure which resulted in increased crushing resistance per contact area of the sample.

Drag of a cylindrical object in a two-dimensional granular environment

The drag of a cylindrical object in a two-dimensional granular environment is numerically studied. It is found that the drag law is fitted by the sum of the yield force and the dynamic force, the latter of which is reproduced by a simple collision model. The angular dependence of the radial stress on the surface of the object is given by the Gaussian below the yield force. The probability of the velocity drops of the object is investigated above the yield force, where this probability is independent of the packing fraction and the drag force.

Seismic Performance of the Buckling-Restrained Brace Central Buckle for Long-Span Suspension Bridges

In this paper, a novel central buckle composed of buckling-restrained braces (BRBs) is developed for long-span suspension bridges, and its preliminary design procedure is presented. Seismic performance of suspension bridges equipped with BRB central buckles is investigated and compared with those with conventional central buckles (e.g. rigid or flexible central buckles). Furthermore, the effect of BRB yield force, as well as the effectiveness of BRB central buckles combined with viscous dampers, is evaluated using parametric analyses. The results indicate that the BRB central buckle is more effective than other central buckles in reducing both the longitudinal girder displacements and force demands on towers during an earthquake. Furthermore, the combination of BRB central buckles and viscous dampers is a superior option for mitigating the seismic response of long-span suspension bridges.

Suture constructs for rehabilitation using early active motion after tendon transfer surgery

The purpose of this study was to better define an ideal tendon transfer suture construct to allow for early active range of motion. A side-to-side tendon construct was used to test suture technique (cross stich vs. Krackow stitch), number of suture throws, and calibre of suture. A minimum load to failure of 100 N was used to comfortably allow early motion while minimizing rupture risk. All constructs tested, except the 4-0 Krackow construct, were strong enough to withstand 100 N of load. The choice of suture should be based on surgeon preference, patient compliance, and specific surgery, and 3-0 non-absorbable suture may be more suitable for tendon transfers from a yield force standpoint.

STUDI PERKUATAN BALOK BETON BERTULANG DENGAN STRAND TANPA PENEGANGAN DAN TULANGAN U

ABSTRACTIncreasing capacity of structures can be done by various methods, one of them is by reinforcing on bridge structure.Reinforcement by using strand has been used on building construction but on reinforced concrete beams because of the problems on it’s execution. The focus of this research is how to install non-stressing strand as reinforcement material.The basic of the research is full-scalled loading test on structure laboratory. There are 2 loading test samples : a sample without reinforcement (Bo) and a sample with reinforcement(B1). The test specimen will be subjected to static monotonic loading until the collapse. The dimensions of the test specimen are 150 x 300 (mm) and the length of the span is 3200 mm.The result of loading for the reinforced concrete beam and reinforcement beam, the yield force value was 22 kN and 27 kN respectively, while deflection value was 9.5 mm and 13 mm respectively.Keywords: beam, reinforcement, strand without stressing, static load.ABSTRAKPeningkatan kemampuan(kapasitas) infrastruktur khususnya jembatan dapat dilakukan dengan berbagai metode, salah satu untuk meningkatkan kemampuan tersebut dengan memperkuat jembatan.Perkuatan menggunakan strand sudah digunakan pada berbagai konstruksi bangunan tetapi untuk balok beton bertulang belum banyak dilakukan karena akan mengalami kesulitan dalam metode pelaksanaan. Sehingga dalam penelitian ini akan mencoba menggunakan metode pemasangan strand tanpa penegangan sebagai bahan perkuatan.Penelitian dilakukan dengan cara pengujian eksperimental di laboratorium dan. Benda uji yang digunakan terdiri dari 2(dua) buah yaitu 1(satu) benda uji balok beton bertulang tanpa perkuatan(Bo) dan 1(satu) buah benda uji balok beton bertulang dengan perkuatan(B1). Benda uji akan dilakukan uji pembebanan statikmonotonik sampai mengalami keruntuhan. Dimensi benda uji 150 x 300 (mm) dan panjang bentang 3200 mm.Dari hasil pengujian terhadap balok beton tanpa perkuatan dan balok perkuatan didapatkan nilai gaya leleh berturut – turut sebesar 22kN dan 27kN serta lendutan berturut –turut sebesar 9.5 mm dan 13 mm.Kata kunci : balok, perkuatan, strand tanpa penegangan, beban statik

Effect of a Surface Constraining Layer on the Plastic Deformation of Au Microspheres

ABSTRACTSingle crystal Au microspheres, of 3 μm diameter, with sputter-deposited Ni surface layers, of 40 or 80 nm thickness, were tested in compression at three loading rates to investigate the role of thin passive layers on the mechanisms of plastic deformation of small-volume FCC ductile metal samples. The Ni layer resulted in an increase in the incipient yield force by about 10%. Micro-cracking of the Ni layer was observed to occur with incipient yielding. The estimated apparent activation volume of the incipient plastic deformation process was found to be nearly identical for the Ni-coated and the uncoated Au microspheres. This suggests that, while the stress required to initiate incipient plastic deformation was increased by the constraint imposed by the Ni layer, the subsequent plastic flow occurred by a dislocation nucleation and glide mechanism that is essentially the same as that occurring in an unconstrained Au microsphere.

CHEMICAL AND MECHANICAL PROPERTIES OF VELVET TAMARIND FRUIT (DIALIUM GUINEENSE)

Information on chemical properties of fruits is crucial in processing it into different foods. Mechanical properties of fruits determine their susceptibility to mechanical damages that occur during harvest, transportation, and storage; and which eventually lead to a pronounced reduction in commercial value. This study was conducted to investigate the chemical and mechanical properties of unshelled (black), shelled (yellow) and kernel of Dialium guineense fruit. The chemical properties investigated include some proximate and mineral elements. The mechanical properties were bio-yield force, rupture force, deformation at rupture point, deformation ratio at rupture point, compressive strength and total strain energy. The fruit pulp was found to be composed of protein (9.4%), carbohydrate (75%), crude fat (5.2%), crude fibre (4.6%), and ash content (2.4%) at 19% moisture content (wb). The mineral composition of the pulp were sodium (3.2 g/kg), magnesium (2.9 g/kg), phosphorus (0.5 g/kg), calcium (0.5 g/kg), iron (0.1 g/kg), and vitamin C (0.3 g/kg) at a pH of 3.9. Less force is required to crack the fruit across the length, followed by across the thickness and then across the width. Velvet tamarind (Dialium guineense) fruit pulp is a promising source of food and essential minerals due to its nutritional values, hence facilitating its postharvest processing is inevitable. http://dx.doi.org/10.4314/njt.v36i1.30

Bolts Gauge Effect on the Face Bending Behaviour of Concrete-Filled Hollow Section for Hollo-Bolted Connections

This paper investigates the effect of bolt gauge on the face bending behaviour of concrete-filled Square Hollow Sections (SHS) in Hollo-Bolted connections. A set of full-scale experiments were undertaken to examine the effects of varying the bolt gauge on the SHS face bending behaviour while controlling all other parameters. Typical experiment involved one row of two bolts pulled out of concrete-filled SHS. A special dummy bolts were manufactured to the exact size and geometry of open Hollo-Bolts, and were used in the experiments to remove the influence of any deformation associated with the real Hollo-Bolts, and isolate the face bending behaviour. Non-contact video-based equipment was used to record the SHS face deformation. This deformation is recorded as force-displacement relationship which is commonly used to represent the structural behaviour of similar components, and typically defined by initial stiffness, yield force and post yield stiffness. Across the range considered in this investigation, it was found that varying the bolt gauge to SHS width ratio have a significant effect on the concrete-filled SHS face in bending component. Both the initial stiffness and the yield force of the component were found to increase with the increase of the bolt gauge. The Post-Yield stiffness was not affected by the change in bolt gauge.