Experimental and Numerical Study of Octagonal Composite Column Subject to Various Loading

In this study, experimental tests of the behaviour of steel and partially encased composite (PEC) columns subjected to compressive loading is performed. Evaluation of this type of composite column under axial loading and numerical analysis of its behaviour under combined torsional and axial loading are the main objectives of this study. At first, a parametric study of PEC columns under axial loading was performed in order to find the relationship between flange slenderness ratio of steel column section and concrete confinement. Width-to-thickness ratio of the flange, diameter and spacing of the transverse links were considered as variables in this study. It was observed that dimension of transverse links had almost no effect on the capacity of the specimens, however smaller transverse links spacing increased both capacity and deformability of the specimens. The comparison of the code equations given in CSA S16-14 and EN 1994-1-1 revealed that the equation in CSA S16-14 underestimates the capacity. Furthermore, different types of retrofit of cross-shaped steel column including concrete encasement, use of stiffener plates and transverse links were investigated in this research. Results revealed that concrete confinement and use of transverse links had respectively the most and the least effect on increasing torsional capacity of the specimens

Experimental and Numerical Investigation of Octagonal Partially Encased Composite Columns Subject to Axial and Torsion Moment Loading

This paper includes experimental and numerical study of the octagonal partially encased composite (PEC) columns specimens under axial and torsion loading. The major difference between them was the concrete reinforcement details. The parameters investigated in the experimental and numerical study were the type of reinforcement details, the failure mode, width-to-thickness ratio of flange, transverse links spacing and diameter. The results were presented as load-deformation curves. Numerical model was validated using finite element method and the results indicated acceptable accuracy with tests results in the form of capacity and ductility. In the analytical phase, the experimental results in the compressive loading were compared with those obtained from CSA S16-14 and EN 1994-1-1 equations. Also, the new concrete confinement factor in proportion to the web width to thickness ratio was presented to octagonal PEC columns under pure compressive load. Furthermore, different types of retrofit of cross-shaped steel column including concrete encasement, use of stiffener plates and transverse links were investigated in this research. Results revealed that concrete confinement and use of transverse links had respectively the most and the least effect on increasing torsional capacity of the specimens

Numerical and parametrical investigations of the behavior of composite steel plate shear walls with opening

The use of steel shear walls has been considered as a lateral load-bearing system in tall buildings. The significant advantage of Composite Steel Plate Shear Wall (CSPSW) is that the buckling of the infill steel plate, which is a serious disadvantage of Steel Plate Shear Wall (SPSW), is prevented. In order to enhance the seismic behavior of the system, the analytical study of CSPSW with a reinforced concrete panel with a gap between the concrete panel and steel frame was conducted. Hence, CSPSWs could be considered as an alternative lateral resistance system in steel structures, which is typically utilized as an effective lateral load-resisting system in high-rise buildings, where the story shear loads were markedly large. In this study, several parameters such as opening shape, opening location, and opening area in composite steel plate shear wall were considered in nonlinear static analysis using ABAQUS software. The numerical model was validated using an experimental model that had differences of 2.3% and 2.9% in elastic stiffness and load-bearing capacity, respectively. After ensuring proper performance and accuracy in predicting the behavior of the system, 16 numerical finite element models were simulated. The analysis results showed that using the concrete panel caused by transferring the failure mode from steel plate failure and buckling of plate to cracking and crushing the concrete led to a 13% increase in the load-bearing capacity. The most suitable type of opening shape is circular in shape with a load-bearing capacity of 5% more than the rectangular shape. Also, using a square opening can create the highest ratio of opening without geometric interference with other members in the shear wall. The behavior of CSPSWs and corresponding SPSWs is utterly disparate. The infill steel plate of SPSW resists lateral load by the development of tension fields as the infill steel plate initiates elastic buckling. However, in CSPSW, the elastic buckling of the infill steel plate is prevented by introducing a reinforced concrete panel; hence, the infill steel plate carries out lateral load by pure shear yield. Moreover, during the lateral load, CSPSW undergoes four stages: initial elastic stiffness, shear yield stiffness, post-shear yielding stiffness, and pre-failure stiffness

Effects of beech and eucalyptus sawdust as a supplementary material to improve the performance of composite panel

The use of wood fibers and recycled paper fibers in cement composites has many advantages. Wood fiber reinforced composites are easy to cast or mold into a desired shape, resistant to fire, as well as being resistant to harmful effects of sunlight, rain, and insects. These composites also have low thermal conductivity, a great degree of processing flexibility, in addition to helping eliminate environmental pollution by recycling wood fiber. The present study seeks to investigate the effect of eucalyptus and beech wood flour on the mechanical properties of wood–cement composites. Five levels of wood (0%, 8%, 20%, 32% and 40%) and one level cement (60%) were used. Totally 15 composites were produced. The composites were manufactured using hot press and tested based on DIN 68763 standard. After preparation of test samples, mechanical properties (bending and hardness) and physical properties (water absorption and thickness swelling) were measured. Results showed that addition of both fillers reduced modulus of rupture and increased modulus of elasticity, water absorption and thickness swelling. The Eucalyptus present in composite wood-cement caused a reduction in mechanical and physical properties can use with Beech wood flour

Effect of seismic soil-pile-structure interaction on midand high-rise steel buildings resting on a group of pile foundations

A series of numerical simulations were carried out on two types of superstructures and six types of piled raft foundations to investigate the effects of seismic soil-pile-structure interaction (SSPSI) on the seismic responses of the superstructures. In this research, the effectiveness of a piled raft application was assessed; the pile optimum numbers, locations, and configurations were estimated; and finally, a comparison was made between the nonlinear structural responses of the obtained two-dimensional (2D) and three-dimensional (3D) models. Parametric studies were conducted to achieve strategies for optimized designs of piled raft foundations subjected to the low-to-high intensities of real earthquake records as the input motions. The numerical results represented a reasonable correlation between the shaking intensity rates (SIRs) and maximum interstory drifts of the structures. It was discovered that the performance levels of the structures on a softened ground were a function of the area replacement ratios, lengths, diameters, and spaces between the piles; ground motion features; and height/width ratios of the structures. These important aspects had to be regarded to achieve a reliable design. The aim of this investigation was to ameliorate the characteristics of a system of long-short combined piled raft foundations based on an understanding of the interaction mechanics. © 2018 American Society of Civil Engineers

Three-Dimensional Printing of Structural Members with Shotcrete Technique: Design, Construction, and Future Directions

This paper provides a comprehensive review of the current state of 3D printing technology in the construction industry, highlighting the potential applications, benefits, and future directions of this emerging field. The review indicates that 3D printing technology has the potential to revolutionize the construction industry by offering more efficient, precise, and sustainable methods of construction. The technology offers numerous advantages, including the ability to create complex geometries and custom components, improved precision and accuracy, reduction in waste materials, improved worker safety, and potential for use in remote or inaccessible locations. Furthermore, the advent of additive manufacturing, colloquially known as 3D printing, presents prospects for the advancement of novel material compositions, printing methodologies, and cybernetic systems that have the potential to optimize the efficiency and effectiveness of the construction domain. Future research should focus on developing larger printers with more efficient support structures, improving the accuracy and speed of printing, and exploring the potential of using new and innovative materials in the construction process. Additionally, the environmental impact of 3D printing technology should be further examined, particularly in terms of its potential for reducing waste and energy consumption in the construction industry. Overall, the potential utilizations and advantageous outcomes stemming from the implementation of 3D printing technology within the construction sector are momentous. Persistent exploration and innovation within this realm hold the capacity to engender noteworthy strides in construction technology and foster heightened sustainability within building methodologies

Evaluation of Treatment Factors Response to Methotrexate Treatment in Ectopic Pregnancies in Imam Khomeini Hospital, Sari, 2016-2021

Background and purpose: After a diagnosis of ectopic pregnancy there are two choices for treatment: medical treatment with methotrexate and surgical treatment. It seems that medical treatment, has had acceptable success compared to surgery and lacks the complications of surgery. Nowadays, due to the progress achieved in the early diagnosis of ectopic pregnancy, a large number of patients are candidates for medical treatment. This study is conducted to evaluate the effective factors of medical treatment Response with methotrexate in ectopic pregnancies. Materials and methods: In this case-control study, the information related to patients who were diagnosed with ectopic pregnancy and were treated with methotrexate from March 2016 to March 2021 in Imam Khomeini Hospital in Sari was examined using hospital records by census method. In total, 160 patients out of 623 patients met the inclusion criteria and were studied. In the checklist prepared for each patient, the patient's age, number of gravity and parity and abortion, previous history of infertility, contraceptive method, presence of clinical symptoms (such as abdominal pain-vaginal bleeding-amenorrhea), History of using recent assisted reproductive methods, type of treatment regimen used (Single/Multiple Dose), serum beta human chorionic gonadotropin (BHCG) level before and after starting treatment, number of previous ectopic pregnancy, gestational age based on the last Menstruation, transvaginal ultrasound results(including the presence of the yolk sac & fetal heart rate & hematosalpinx - location and size of the ectopic mass-endometrial thickness) were recorded for each patient separately, The patients were divided into two categories: success and failure of treatment and the effect of different factors on the result of medical treatment with methotrexate was investigated. The collected data were entered into SPSS 26 software and qualitative variables were analyzed with the Chi-Square test. The normality of the distribution of quantitative variables was measured by the One-Sample Kolmogorov-Smirnov test, an independent t-test was used to examine quantitative variables with normal distribution, and the Mann-Whitney test was used for quantitative variables with non-normal distribution. Results: 160 patients were included in this study, 108 of patients (67.5%) were successfully treated and 52 patients (32.5%) faced treatment failure. In this study, the type of treatment regimen (P=0.001), Serum Beta Human Chorionic Gonadotropin (BHCG) level before treatment(P=0.000), BHCG level after treatment (P=0.000), the presence of fetal heart rate (P=0.002) and yolk sac (P=0.046) are factors affecting the response to methotrexate treatment in ectopic pregnancy. The presence of hematosalpinx, size of the ectopic mass, endometrial thickness, history of infertility and recent assisted reproductive procedures, presence of clinical symptoms, contraceptive method, gestational age, history of ectopic pregnancy, number of gravidity and parity, and abortion have no effect on the results of medical treatment with methotrexate. Conclusion: Based on the results obtained, Single Dose regimen of methotrexate treatment is associated with greater treatment success than a multiple-dose regimen and also high serum BHCG levels before and after the treatment, the presence of fetal heart rate and yolk sac in transvaginal ultrasound are factors to increase the probability of failure of medical treatment of ectopic pregnancy with methotrexat

Numerical 3D Finite Element Assessment of Bending Moment-Resisting Frame Equipped with Semi-Disconnected Steel Plate Shear Wall and Yielding Plate Connection

Steel plate shear walls (SPSWs) have advantages such as high elastic stiffness, stable hysteresis behavior, high energy absorption capacity, and decent ductility. However, one of the main drawbacks of SPSWs is their buckling under lateral loading. To address this issue, a simple and practical solution in the form of using a trapezoidal plate moment connection (PMC) and a narrow gap between the infill plate and columns is presented. The PMC will act as an energy absorber, similar to a yielding steel plate, and keep the other structural members in an elastic state. Extensive three-dimensional finite element (FE) models of the SPSW system were investigated under monotonic and cyclic loading. The results revealed that by separating the infill plate from the vertical boundary elements and using two vertical edge stiffeners at both edges of the wall, the same lateral bearing capacity of the conventional system can be achieved. In addition, by increasing the thickness of the PMC from 6.5 to 26 mm, the load-bearing capacity, energy dissipation, and elastic stiffness increased approximately 2, 2.5, and 3.2 times, respectively. It was also found that the flexural capacity ratio of the connection to the beam had little effect on the overall force–displacement behavior. However, it can affect the system failure mechanism. Finally, the tension field inclination angle for such SPSWs was proposed in the range of 30 to 35°