Full Load Displacement Research Articles

Deformability and ductility in over-reinforced concrete structures

It is often useful to use a high percentage of steel reinforcement in a concrete flexural member in order to minimise structural depth and still provide adequate stiffness. This paper shows that, by placing a steel helix in the compression zone of a heavily over-reinforced concrete beam, considerable strength, stiffness and ductility may be achieved, even when the steel percentage is as high as 7%. This is because the concrete in compression becomes triaxially stressed and confined during loading, leading to a high uniaxial strain capacity in the concrete at an enhanced stress level. It is shown that, even though the serviceability limit states of deflection and cracking are critically important, they are just satisfied under normal conditions. The testing programme described here consisted of seven tests on rectangular steel-reinforced concrete beams. Each helically reinforced specimen contained a single helix with a 20 mm pitch. The helices were formed from either 3 mm or 4·8 mm diameter mild steel wire. To show the full benefit of the presence of a circular helix, control specimens (no helix) and specimens containing a similar volume by weight of rectangular links were tested for direct comparison purposes. This research is exciting, as it demonstrates that it is possible to heavily over-reinforce concrete structures and nonetheless expect a ductile response. This is potentially very useful to clients, consultants and contractors who wish to use shallower concrete members. Further, two analytical approaches are developed here for predictive assessment. A full load–displacement approach is presented, followed by a simpler design-oriented approach. Both methods predict behaviour reasonably accurately.

Deformability and ductility in over-reinforced concrete structures

It is often useful to use a high percentage of steel reinforcement in a concrete flexural member in order to minimise structural depth and still provide adequate stiffness. This paper shows that, by placing a steel helix in the compression zone of a heavily over-reinforced concrete beam, considerable strength, stiffness and ductility may be achieved, even when the steel percentage is as high as 7%. This is because the concrete in compression becomes triaxially stressed and confined during loading, leading to a high uniaxial strain capacity in the concrete at an enhanced stress level. It is shown that, even though the serviceability limit states of deflection and cracking are critically important, they are just satisfied under normal conditions. The testing programme described here consisted of seven tests on rectangular steel-reinforced concrete beams. Each helically reinforced specimen contained a single helix with a 20 mm pitch. The helices were formed from either 3 mm or 4·8 mm diameter mild steel wire. To show the full benefit of the presence of a circular helix, control specimens (no helix) and specimens containing a similar volume by weight of rectangular links were tested for direct comparison purposes. This research is exciting, as it demonstrates that it is possible to heavily over-reinforce concrete structures and nonetheless expect a ductile response. This is potentially very useful to clients, consultants and contractors who wish to use shallower concrete members. Further, two analytical approaches are developed here for predictive assessment. A full load–displacement approach is presented, followed by a simpler design-oriented approach. Both methods predict behaviour reasonably accurately.

Crack face interaction and mixed mode fracture of wood composites during mode III loading

A new testing setup to perform and measure mode I, mode III and mixed mode experiments is applied to wood composites with varying particle size. Specimens of particleboard, MDF (medium density fiberboard) and INTRALLAM LSL ® are tested under mode I and mode III loading conditions. As testing procedure and specimen geometry allow steady state crack propagation, full load displacement curves can be recorded until complete separation of the specimen takes place. Using a special specimen geometry, large crack lengths may be obtained. The testing method is sensitive enough to investigate the mode I crack opening induced by fracture surface asperities during mode III loading, without external mode I loading and therefore the amount of arising intrinsic mode mixity.

Characterization of crack propagation in particleboard

In this paper the wedge-splitting-method (Tschegg 1986) for mode I-testing was applied to specimens of particleboard. Specimen geometry and loading-device used for this method allow testing under the condition of steady state crack propagation. Therefore the full load-displacement curves can be recorded. Using the loaddisplacement-curves, different ways of evaluation have been carried out to determine relevant fracture properties like the specific fracture energy Gf and the crack resistance Rc of the investigated material for two different orientations.

Achievements with Advanced Craft

ABSTRACT Progress in the performance of advanced craft and the merits of various hull forms differ with respect to the technological maturity of each concept. Full‐scale, calm water trial data of speed and power for known displacement transport efficiency is used to compare the optimum performance of several hull forms such as planing, round bilge, stepped, catamaran and SES. Transport efficiency comparisons for a wide range of dimensionless speeds have been updated for trial results through the beginning of 1993. Trends that demonstrate increased transport efficiency are discussed when sufficient information is available to define resistance to weight ratios and overall propulsive efficiencies. Finally, data for useful load fraction, defined as the combination of payload and fuel weight relative to design full load displacement are presented for hard chine and SES craft.

Development of a 3D CAD System for Hull Form Design

At the initial design, estimate of key numbers such as resistance, displacement, dead weight, light weight, and so forth is required using only a few parameters (e.g.L, B, D, or Cp). Among these key numbers, full load displacement, cargo hold capacity, rough arrangement and so forth. can be estimated accurately if the hull form is defined. Authors made a prototype 3D CAD system for initial hull form design based on the Pro/ENGINEER with using its customizing module. This system makes use of a template ship consisting of side and bottom flat, bilge circular, bow and stern free surfaces. Users can get a desired ship from the template, modifying the lines between these surfaces and spline surfaces in bow and stern. It can also provide hydrostatic curves, lines and Cp curve of the obtained hull form.

各種漁船の漁獲性能特性に関する研究 Ｉ 正準相関分析による各種漁船の諸要目間の関係について

The relations among principal items of 8 types of fishing boats were analyzed using Canonical Correlation Analysis, and the features were extracted on the basis of analyzing results, and were compared thoroughly with the actual principal items. Here, from our studies, three ratios of (fish hold)/(length between perpendiculars×molded breadth×molded depth), (main engine horsepower)/(full load displacement), and (sea speed)/(length between perpendiculars)1/2 are noteworthy as the best expressions of the features of fishing boats. We adopted these ratios and scalar quantities lead from the basic principal items as the de-pendent variables and the independent ones, respectively, and conducted the analysis. Consequently, the features of fishing boats of 8 types were obtained. The Canonical Cor-relation Analysis was available here. Our final purposes are, using our results, grouping for general types of fishing boats, and contributions to the safety of fishing boats and to the elevation of fishing performance.

SHIP DESIGN MARGINS‐ISSUES AND IMPACTS

ABSTRACTThe generally accepted categories of Design and Construction Margins and Future Growth Margins are discussed briefly, and a third major category, Assurance Margins, is introduced and discussed in more detail. The connection between Assurance Margins and the probability of successful performance is shown. The feasibility of reducing margins to reduce ship size and cost is examined.Following a brief discussion of certain significant aspects of a version of the Naval Ship Engineering Center DD07 destroyer computer synthesis model and of the baseline ship employed, the results of some computer studies of margin impacts on that baseline ship are presented and interpreted. Changes in margins on weight, vertical center of gravity, space, accommodations, propulsion power, and electrical power are investigated and their impacts expressed primarily as changes in full load displacement and in acquisition cost. The effects of combinations of margins are illustrated, and attempts are made to explain the mechanisms by which interactions occur.

Marginal Cost—A Tool in Designing to Cost

ABSTRACTThe concept of marginal cost, i.e., the cost of one additional unit at some specified level, can be applied to naval ship design with considerable benefit. Weight, space, electric power and manning are commodities by which most subsystems and equipments influence ship size and cost. By developing marginal cost factors about a base‐line design for these commodities, it is possible to estimate the shipboard cost influence of a wide variety of subsystems without the necessity of a specific design studies. Answers can be provided in minutes rather than days or weeks. Additionally, marginal cost factors provide the naval architect with a new insight into his design, a guide for trading between commodities, and a means of quickly assessing his capability to reach a target cost.This paper shows the development of marginal cost factors for a Destroyer Escort of about 3,500 tons full load displacement. Potential problem areas are discussed and an example of marginal cost application is offered.

Transoceanic surface effect ships

The advent of new machines using an unexpoited natural phenomenon and offfering man unique transportstioa opportunities imposes new technical problems along with exciting possibilities. In particular, the idea of large-scale ships moving over water at speeds upwards of 100 knots presents special problems requiring special solutions. The surface effect ship (SES) is a fast ocean-going ship employing a self-generated cushion of air for lift support, reduction of resistance, and reduction of rough water loads and motions; such ships are envisioned as capable of approximately 85 knots in sea state 4 and possessing transoceanic range with an economical payload and survivability in the open sea. The minimum size for full satisfaction of these criteria is expected to be about 4000 tons full load displacement. The Navy and Commerce Departments are jointly sponsoring a cooperative research program which is to establish the feasibility of designing and building large high-speed surface effect ships. This paper describes the salient features of such craft, sets forth the regions demanding greatest engineering development, discusses briefly the commercial and military future of SES, and explores the problems associated with multithousand-ton ships moving at 100 knots in opea sea conditions.

Estimation of the Natural Frequency of the Hull in the early Stage of Design

We Propose here a Method of estimating the Natural Frequency of 2-Noded Vertical Vibration For Three Islander or similar type Cargo Ship, on the basis of the measured datas at trials which had been carriedout for about 15 years.Eventualy, the Natural Frequency of the hull (N) is derived From the Following Formula.N=k·307√Ie×108/ {0.88Wh+Σ (e, ω) + (0.98-0.34Cb) (0.21+0.32B/d) Δ} Lp3/min.where Lp : length between perpendiculars in M.B : breadth moulded in M.d : mean draft in M.Cb : block coefficientΔ : displacement in KT.Wh : hull weight in KT.ω : added weight (Cargo, fuel, machinery etc.) in KT.e : a coefficient depending on the position of an added weightle=I⊗+ (Ib-I⊗) 2lh/Lp in M4I⊗ : moment of inertia to upper deck of the midship section in M4.Ib : moment of inertia to bridge deck in M4.lb : length of bridge in M.kx : to be a coefficient bared on the node position and decided after the measured datas.For estimating the natural frequency range in the early stage of design, the approximate values of the natural frequencies at trial and full load conditions are given by the Following formulas. For trial conditionNT=228√Ie×108/ΔTLp3/min.where ΔT is the displacemnet at trial about 40% of full load displacement For full load conditionNF=283√Ie×108/ΔFLp3/min.where, ΔF is the full load displacement