Bearing Capacity and Mechanical Behavior of an Innovative Bamboo Fiber-Reinforced Polymer Tendon with U-Head

The development of steel in engineering structures or components faces the problems of high cost and high carbon emission, which demands new materials used as reinforcement to be proposed and applied. Bamboo is a green and renewable natural material, and has higher tensile strength parallel to grain compared to wood. Based on the excellent mechanical properties in the parallel-to-grain direction of bamboo fiber, this paper proposed an innovative bamboo fiber-reinforced polymer tendon with U-head (BFRP tendon). To analyze the tension capacity and mechanical behavior of the BFRP tendon, the thin-shell model and thick-shell model have been proposed in succession. Both models were compared with the results of tensile test and good agreement was achieved in the stress distribution and the ultimate load. The tension capacity of the BFRP tendon has been proved to be reliable, which can give full play to the advantages of bamboo fiber.

Reliability and uncertainty quantification of the net section tension capacity of cold-formed steel angles with bolted connections considering shear lag

In cold-formed steel members under tension and connected with bolts, the resistance capacity of the net section should be calculated, taking into account the shear lag phenomenon. This is done through the net section reduction coefficient, Ct. Different Standards show different equations for Ct. In this work, experimental laboratory data of cold-formed steel angles from the authors are used for the evaluation of the accuracy of the predictions of the net section capacity of members under tension. Such predictions are given by the equations of AISI, Eurocode-3, Brazilian standard NBR 14762, and also by a predictive equation previously proposed by the authors. The paper shows how each equation predicts the tension member resistance capacity in front of the experimental data. Most of the equations in the design standards have good predictions when more sections of the steel angles are connected. The results show that the AISI standard presented the best resistance capacity prediction and lower standard deviations of the output response upon uncertainty.

Load Capacity of Shallow Embedded Anchor Channels

Anchor channels are cast in concrete and allow the connection of components using channel bolts. In recent years, the design to value resulted in ever thinner concrete elements, which often cannot accommodate the required embedment depth of standard anchor channels. For this reason, channels may be fitted with short anchors. While existing design provisions allow for the calculation of the tension capacity also for shallow embedded anchor channels, tests are required to determine product-specific parameters for the economic shear loads design. The presented study investigated the performance of shallow embedded anchor channels tested in shear. The detailed evaluation of the test data demonstrates that testing of the minimum embedment is conservative and that the load-displacement behavior of channels with welded I-sections is comparable to that of channels with forged headed studs. In addition, a new evaluation approach is proposed.

Uplift performance of helical piles with cement injection in residual soils

Helical piles have been widely used in Brazil to resist uplift forces of transmission line towers due to certain advantages compared with other foundations, such as resistance to both compressive and tensile loads, easy transport to remote sites, possibility of installation at batter angles, rapid installation with small equipment, and no need for concrete and formwork. However, in some sites the appropriate soil layer for the installation of the pile helices is too deep or too hard to be penetrated. In these cases, the use of helical foundations is not economically and (or) technically viable. One possible solution for this problem is to install the pile in a soil with low bearing capacity improved with cement injection. To evaluate the applicability of a soil-treatment method for helical piles, two different procedures of injection were tested in typical Brazilian residual soils of different geologic origin. For this investigation, 41 multi-helix piles (15 conventional piles and 26 with cement injection) were installed and submitted to tensile loading tests. The results reveal that both techniques can improve the tension capacity and produce a stiffer load–displacement response of helical piles under uplift loads.

The Effect of Weld Length on the Tension Capacity of Hollow Structural Section (HSS)

The non-uniform stress distribution occurs in a tension member adjacent to a connection, in which all elements of the cross-section are not directly connected. This effect reduces the member’s design strength because the entire cross-section is not fully effective in the critical section’s location. That's why an experimental study has been done to investigate the effect of the weld length on the tension capacity, two specimens (hollow structural sections) have been tested by using Instron 8800 machine with two weld lengths, 46 mm and 56 mm. The 46 mm size is the minimum requirement of the sufficient size of the tension connection depending on United States Steel Standard. The Result proved that there has been too much effect on the connection carrying tension capacity. The result of the 46 mm weld length is about 155 KN and about 180 KN for the 56 mm weld length. While the ABAQUS simulation results were about 168 KN for the 46 mm weld length and about 172 KN for the 56 mm weld length.

A STUDY ON ANALYTICAL T-STUB PRYING MODELS FOR RHS JOINTS IN TENSION

The article investigates analytical models for calculation of tension capacity of axially-loaded RHS end-plate joints bolted along two and four sides of the tube in order to investigate the phenomena of prying. Design of such joints is impeded by lack of rules in EN 1993-1-8 and it raises the question whether the Eurocode 3 equivalent T-stub in the tension component should contain integrated assumptions from the AISC/CIDECT/CISC design guides. This paper considers the effect of the bolt hole on the length of the plastic hinge and compares different T-stub models with various assumptions. The behaviour and collapse mechanism of joints with non-preloaded and preloaded bolts was tested during an experiment. The statistical analysis of the test results of 47 joints found in the literature in conjunction with 7 tests determined that it was preferable to use a common approach for connections bolted along two and four sides. Additionally, a limitation of a minimum flange thickness is specified. The performed research has disclosed the benefits and shortcomings of the T-stub models and justified recommendations for their improvement.