Fish Anchor Dived – Confirmation Through Field Tests in the Swan River

This paper reports the results from field tests on a 1/15th scale recently developed fish anchor. The tests were conducted at three locations in the Swan River, Perth. Two series of tests were performed from the Burswood and Maylands jetties with water depths between 1.1 and 1.9 m. The final series of tests were undertaken in deeper waters of 2.6 m from a barge. The riverbed at the Burswood Jetty and barge test location consisted of soft clay, and that at the Maylands Jetty comprised sandy silt. The tip embedment depths of the scaled fish anchor, with dry weight of 0.304 kN and impact velocity of 5.89∼9.55 m/s, in soft clay were 1.17∼2.40 times the anchor length. For similar impact velocities, the tip embedment depths in sandy silt were 30 ∼ 60% shallower than those in soft clay. By comparing the field test data in clay, the fish anchor achieved normalised embedment depths similar to those of the torpedo and OMNI-Max anchors under half or less impact velocity. Most importantly, the field tests confirmed the diving behaviour of the fish anchor under loading with mudline inclination of 20° and 25°, with the second peak dictated the capacity. The ultimate capacity was 5∼7 times the anchor submerged weight in water.

From the Atlantic Coast to Lake Tanganyika: Gill-Infecting Flatworms of Freshwater Pellonuline Clupeid Fishes in West and Central Africa, with Description of Eleven New Species and Key to Kapentagyrus (Monogenea, Dactylogyridae)

Unlike their marine counterparts, tropical freshwater clupeids receive little scientific attention. However, they sustain important fisheries that may be of (inter)national commercial interest. Africa harbours over 20 freshwater clupeid species within Pellonulini. Recent research suggests their most abundant parasites are gill-infecting monogenean flatworms within Kapentagyrus. After inspecting specimens of 12 freshwater clupeids from West and Central Africa, mainly sourced in biodiversity collections, we propose 11 new species of Kapentagyrus, which we describe using their haptoral and genital morphology. Because of their high morphological similarity, species delineation relies mostly on the morphometrics of anchors and hooks. Specifically, earlier, molecular taxonomic work indicated that the proportion between the length of the anchor roots, and between the hook and anchor length, is diagnostic. On average, about one species of Kapentagyrus exists per pellonuline species, although Pellonula leonensis harbours four species and Microthrissa congica two, while Microthrissa moeruensis and Potamothrissa acutirostris share a gill monogenean species. This study more than quadruples the number of known species of Kapentagyrus, also almost quadrupling the number of pellonuline species of which monogeneans are known. Since members of Kapentagyrus are informative about their hosts’ ecology, evolutionary history, and introduction routes, this enables a parasitological perspective on several data-poor African fisheries.

From the Atlantic Coast to Lake Tanganyika: Gill-Infecting Flatworms of Freshwater Pellonuline Clupeid Fishes in West and Central Africa, With Description of Eleven New Species and Key to Kapentagyrus (Monogenea, Dactylogyridae)

Unlike their marine counterparts, tropical freshwater clupeids receive little scientific attention. However, they sustain important fisheries that may be of (inter)national commercial interest. Africa harbours over 20 freshwater clupeid species within Pellonulini. Recent research suggests their most abundant parasites are gill-infecting monogenean flatworms within Kapentagyrus. After inspecting specimens of 12 freshwater clupeids from West and Central Africa, mainly sourced in biodiversity collections, we propose 11 new species of Kapentagyrus which we describe using their haptoral and genital morphology. Because of their high morphological similarity, species delineation relies mostly on morphometrics of anchors and hooks. Specifically, earlier, molecular taxonomic work indicated that the proportion between the length of the anchor roots, and between hook and anchor length, are diagnostic. On average, about one species of Kapentagyrus exists per pellonuline species, although Pellonula leonensis harbours four species and Microthrissa congica two, while Microthrissa moeruensis and Potamothrissa acutirostris share a gill monogenean species. This study more than quadruples the number of known species of Kapentagyrus, also almost quadrupling the number of pellonuline species of which monogeneans are known. Since members of Kapentagyrus are informative about their hosts’ ecology, evolutionary history, and introduction routes, this enables a parasitological perspective on several data-poor African fisheries.

Analytical Calculation of Critical Anchoring Length of Steel Bar and GFRP Antifloating Anchors in Rock Foundation

Antifloating anchors are widely used during the construction of slab foundations to prevent uplift. However, existing methods for calculating the critical length of these anchors have limited capabilities and therefore require further research. As the mechanisms which govern the displacement and stability of antifloating anchors are closely related to those of piles subject to uplift, a simplified anchor model has been developed based on existing concentric thin-walled cylinder shear transfer models used for pile design. Analytical expressions for the critical length of the steel bar and GFRP (glass fiber reinforced polymer) antifloating anchors in rock are derived accordingly before demonstrating the validity of the method through engineering examples. The research results show that when the length of an antifloating anchor is less than a critical length, shear slip failure occurs between the anchor and surrounding material due to excessive shear stress. When the length of an anchor approaches the critical length, the shear stress gradually decreases to the undisturbed state. If the anchor length is larger than the critical length, the uplift loads are safely transferred to the ground without causing failure. The ratio of elastic modulus between the anchor and rock mass was found to be positively correlated with the critical anchoring length. Because the elastic modulus of GFRP bars is lower than that of steel bars, the critical anchoring length of GFRP bars is greater than that of steel bars under the same anchor-to-rock modulus ratio (Ea/Es). The results show that the proposed calculation method for the critical length of antifloating anchors appears valid and could provide a theoretical basis for the design of antifloating anchors after further refinement.

Stability of Anchored Retaining Walls Under Seismic Loading Conditions to Obtain Minimal Anchor Lengths Using The Improved Failure Model

Anchored retaining walls are structures designed to support different loading applied in static and dynamic cases. The purpose of this work is to design and study the stability of an anchored retaining wall loaded with different seismic actions to obtain minimal anchor lengths. Mononobe-Okabe theory has been applied for the evaluation of seismic earth pressures developed behind the anchored wall. Checking the dynamic stability of anchored retaining walls is usually done using the classic Kranz model. To take into consideration the effects of the internal forces developed during failure, we have proposed a new model, based on the Kranz model, which will be used as the Kranz model to find the critical angle failure performed iteratively until the required horizontal anchor length is reached for a minimum safety factor. The results of this study confirm that the effect of the seismic load on the design of an anchored retaining wall, and its stability, has a considerable influence on the estimation of anchor lengths. To validate the modifications made to the new model, a numerical analysis was carried out using the Plaxis 2D software. The interpretation of the obtained results may provide more detailed explanation on the effect of seismic intensities for the design of anchored retaining walls.

Experimental Study on Influence of Connection Defects on Joint Strength of Half-Grouted Sleeve Splicing of Rebar

The different types of defects of half grouting sleeves will remarkably increase the risks of precast concrete structures. In order to better understand the defects of rebar connections between half grouting sleeves, six different test groups on insufficient grout height, insufficient compactness, rebar offset, insufficient rebar anchor length, overtime grouting, and control group had been researched. The uniaxial tension experiments were conducted for the 24 different specimens, and load-slip curves were also analyzed. The results of the experiments showed that the outside of the rebar was snapped off as for the destruction mode, while the destruction mode changed as the increment of the degree of defect surpasses the critical value. The bearing capacity and deformability were dropped with the increase in the degree of defects, and a critical value of rebar anchoring length of sleeve was discovered. In the end, different finite-element models were built based on different deficient situations, and load-slip constitutive model was obtained, which would be helpful to evaluate the structural performance of precast concrete structures in construction.

A Research on Technology Development in response to Slope Reinforcing Facility (Anchor) Aging

<p>Recently, various drawbacks have been pointed out on the aspects of design, construction, and maintenance of anchor-reinforced slopes, and in some research the causes of increases and decreases of the tension force of the anchor are analyzed. However, research on the development of technology to cope with increases and decreases of the tension force in terms of maintenance is rare. In case that slipping occurs on an anchor-reinforced slope, shear and bending stress will occur in the shear section along the slip surface, and the anchor force may increase when slipping persists due to the deformation of the anchor body. Additionally, if shear deformation occurs in the anchor, cracks will occur in the grout at a relatively low deformation rate, and when deformation continues, the tension force may be further reduced due to the destruction of the grout. We tried to define investigation methodologies and safety plans through the analysis of case studies on functional loss sections, such as fractures of strands due to the excessive load placed on the anchors. From the results of the anchor lift-off test of 466 holes, the number of anchors that could not be retensioned was 177 holes, and the number of anchors with an increased tension force was 49 holes. From the results of ground exploration, it was found that soiled weathering zones or weathering zones with fractured bedrock were distributed at depths of 30m or more. It is analyzed that most anchor settlement with insufficient anchor forces were located in the slip surface and lacked anchor length. It is found that the safety of the slope can be secured if additional reinforcing anchors are installed around anchors with poor strand strength or anchors that cannot be retensioned.(Project Number: 20SCIP-C151408-02).</p>

Anchor Design of a Ring Joint Based on Reliability in a Precast Shear Wall Structure

Precast buildings have been widely used owing to its outstanding features. As these buildings consist of a combination of various components, the mechanical properties of the connections play a critical role in the overall performance of the structure, particularly the vertical connections in shear wall members. A new connection called ring joint is proposed for precast buildings, and test pieces were designed to analyze the anchor performance. The damage phenomena and test data were observed and recorded. The displacement, force, and strain were analyzed, and the results indicated that the anchor length was a key factor and the connection was safe and reliable under reasonable design. Numerical analysis was conducted to explore the mechanical mechanism, and a bearing capacity model was proposed combining the bond and dowel effects simultaneously. Anchor length was determined based on reliability analysis under various conditions, and other suggestions were proposed. All these could guarantee the mechanical properties of the connection, as well as safety and reliability, and promote the popularization and application.

Mechanical Performance Study of Tower Crane Braced Frame Joint with Different Embedded Part Parameters

Embedded part has significant effects on the mechanical performance of tower crane braced frame joint. In this study, a series of experiments with different embedded part parameters are conducted on ultimate bearing capacity, load-displacement relationship, load-strain relationship, failure mode, and failure mechanism. Finite element models are established by the ABAQUS software and compared with the experiment results to verify rationality and credibility of the models. The present experimental study and finite element model analysis focus on the effects of anchor length, anchor width, and endplate area. The research results show that embedded part is pulled out of braced frame joint without plastic deformation, and local stress distribution of braced frame joint is complex with tension, bending, and shear load. The braced frame joint is severely strained and cracked with ultimate bearing capacity. Influence of embedded part parameters on mechanical performance of braced frame joint decreases in the order of anchor length, endplate area, and anchor width. The embedded part parameters have no influence on failure mode but affect the failure mechanism. Ultimate bearing capacity of embedded part is about four times the cracking bearing capacity, and an effective approach to improve ultimate bearing capacity is increasing anchor length. The research results can provide a better understanding of the sensitivity of mechanical and cracking behaviors of tower crane braced frame joint with different embedded part parameters.

Proposed Improvements To Analytical Models of Anchored Retaining Walls

ABSTRACT Anchored retaining walls are restraining walls constructed using anchors to achieve the highest stiffness possible within economic considerations. Anchor length estimation has an important role in the study of the stability of anchored retaining walls. The purpose of this study was to investigate the anchor length using different proposed failure models and Kranz's classic model. In addition, several parametric studies were conducted to find reliable results in the stability analysis of retaining anchored walls with the aim of obtaining stable and shorter anchor lengths. A numerical study was carried out using Geo4 and Plaxis 8.6 software on the same standard profile as analytically studied so as to validate the proposed mechanical models. The failure models proposed in this work are shown to be a useful tool for obtaining stable and shorter anchor lengths for anchored retaining walls.