Types Of Connections Research Articles

Analytical and numerical investigation of the seismic behavior of tubular web reduced beam section connections

AbstractThe reduced beam section (RBS) connections in steel structures are widely used to achieve sufficient ductility and avoid creating brittle failures in moment‐resisting frames. Compared to other types of connections, conventional RBS connections have the potential to reduce moment capacity and induce larger lateral deformation in the structure. In order to resolve this problem, novel forms of RBS connections have been proposed in recent years, such as tubular web RBS connections, which have shown a desirable performance under various loading conditions in previous studies. Therefore, this study conducted an analytic and numerical investigation of this connection under seismic loading. In this regard, the first step is to introduce the analytic equations related to the structural properties and stability of the reduced beam with the tubular web. Using these equations, a comprehensive procedure for the design of the tubular web RBS connections is presented. After that, a numerical model of the tubular web RBS connections is created and then analyzed under cyclic loading using the finite element method in ABAQUS software. Based on the results of this simulation, the suggested connection meets the criteria of valid international standards and can be used in the special moment‐resisting frame. In order to assess the impact of using the proposed connection in moment‐resisting frames, the performance of two 2D moment‐resisting frames with this connection is studied. This study shows that the maximum percentage increase in relative displacement caused by using tubular web RBS connections is 1.68%, whereas this figure rises to 10.6% when conventional RBS connections are used. Therefore, the designers can use tubular web RBS connections instead of conventional RBS connections to increase the lateral stability of the structure and control its lateral deflection due to the seismic loadings without having to increase the dimensions of the frame elements.

252. RIGHT GASTROEPIPLOIC ARTERY LENGTH DETERMINED ANASTOMOTIC LEAKRIGHT GASTROEPIPLOIC ARTERY LENGTH DETERMINED ANASTOMOTIC LEAKAGE AFTER MINIMALLY INVASIVE ESOPHAGECTOMY FOR ESOPHAGEAL CANCER-A PROSPECTIVE COHORT STUDY

Abstract Background This prospective cohort study, conducted at a high-volume esophageal cancer center from July 2019 to July 2022, aimed to investigate the link between the right gastroepiploic artery (RGEA) length and anastomotic leakage (AL) rates following minimally invasive esophagectomy (MIE). Real-world data on stomach blood supply in the Chinese population were examined. Materials and methods A total of 516 cases were enrolled, categorized into two groups based on the Youden index-determined optimal cut-off value for the relative length of RGEA (length of RGEA/length of gastric conduit, 64.69%) through ROC analysis: Group SR (short RGEA) and Group LR (long RGEA). The primary observation parameter was the relationship between AL incidence and the ratio of direct blood supply from RGEA. Secondary parameters included the mean length of the right gastroepiploic artery, greater curvature, and the connection type between right and left gastroepiploic vessels. Patient data were prospectively recorded in electronic case report forms. Results The study revealed median lengths of 43.60 cm for greater curvature, 43.16 cm for the gastric conduit, and 26.75 cm for RGEA. AL, the most common postoperative complication, showed a significant difference between groups (16.88% vs. 8.84%, p = 0.01). Multivariable binary logistic regression identified Group SR and LR (Odds ratio: 2.651, 95% CI: 1.124–6.250, p = 0.03) and Neoadjuvant therapy (Odds ratio: 2.479, 95% CI: 1.374–4.473, p = 0.00) as independent predictors of AL. Conclusions The study emphasizes the crucial role of RGEA length in determining AL incidence in MIE for esophageal cancer. Preserving RGEA and fostering capillary arches between RGEA and LGEA are recommended strategies to mitigate AL risk.

Experimental study on low-cycle fatigue performance of high-strength bolted shear connections

In strong earthquakes, low-cycle fatigue fractures may occur in the bolted connections of steel braced frames. Ensuring a high low-cycle fatigue life for high-strength bolted connections is of paramount significance in enhancing the overall safety and collapse resistance of steel structures. Despite substantial research on plate fatigue failure within bolted connections, there remains a research gap regarding low-cycle fatigue failure of high-strength bolts in these connections. This study aims to address the aforementioned shortcomings by conducting 34 sets of low-cycle fatigue tests on high-strength bolted connections. The test specimens all experienced low-cycle shear fatigue fracture at the threaded or unthreaded portion of the bolt shank as the dominant failure mode. Residual deformations were observed in the holes of connection plates. Based on the test data, ultimate shear capacity of a single shear connection is around 0.61Fy (tensile yield bearing capacity of bolt) when the shear force passes through the unthreaded portion and drops to 0.54Fy for the shear force at the thread. The untreated Q355 (minimum yield strength of 355 MPa) steel surface has an average anti-slip coefficient of around 0.37, while milling reduces it to approximately 0.30. The influence patterns of loading amplitude, bolt material, minimum plate thickness, bolt diameter, shear force position and connection type on low-cycle fatigue life are given by range analysis. Among them, variance analysis shows that loading amplitude and bolt material are the primary influencing factors. The correlation coefficient between loading amplitude and low-cycle fatigue life is −0.92, indicating a strong negative correlation. The degradation amount and rate of anti-slip capacity and shear capacity of bolted connections are also investigated. To propose reliable life prediction method, three models were used to establish the relationship between dimensionless shear deformation and low-cycle fatigue life of 10.9-grade high-strength bolted connections. It is not appropriate to use the fatigue categories defined in current standards to predict the low-cycle shear fatigue life of high-strength bolted connections.

Harvesting Energy from Rainfall: Initial Study by Exploring Diverse Piezoelectric Array Configurations for Enhanced Electricity Generation in Proteus Software

This paper presents an innovative approach to designing and analyzing a simulated piezoelectric energy harvesting system for electricity generation, employing various array connections using Proteus software. The ingenious concept of harnessing energy from rainfall through piezoelectric technology has become an exciting way to turn a common natural occurrence into a possible power source. The rainfall energy harvesting introduces a novel approach that capitalizes on the mechanical energy imparted by raindrops as they strike surfaces, such as rooftops, pavements, or specially designed structures. This study explores distinct piezoelectric connection types to determine their impact on output voltage, focusing on applications such as rechargeable battery and LEDs. The system begins by harvesting vibration and applying it to the piezoelectric disc. The investigation prioritizes identifying the optimal array connection design. Array configurations of series (S), parallel (P), and combination of series-parallel (SP) are assessed in the simulation. Notably, the series connection of 10 units of piezoelectric elements yielded the highest output voltage at 8.5V. The findings provide valuable insights into finding the optimal array connections in enhancing piezoelectric electricity generation. This research contributes to the leading of potential applications of piezoelectric energy harvesting from rainfall, offering insights into a greener and more self-sufficient energy future.

Experimental and numerical study on behavior of demountable T-shaped bolt shear connectors in sustainable composite beams

This paper proposed a new type of demountable T-bolt shear connector to improve the disassembly efficiency of composite beams and realize the sustainable of the structure components. The shear behavior of nine groups of push-out specimens was experimentally investigated through monotonic loading push-out tests. The finite element analysis (FEA) models were validated against the test results, specifically in terms of the load-slip responses and failure modes of the T-bolt shear connectors in these push-out specimens. The obtained results show that all the specimens have no obvious deformation and cracks in the steel beam and RC slab. The separation between the slab and the steel beam is no more than 1 mm, indicating that the anti-lifting ability is excellent. Moreover, parametric analysis demonstrates that increasing the bolt pretension of the T-shaped shear connector and the friction coefficient between the bridge gasket and the steel beam significantly enhances the initial stiffness and ultimate strength of the shear connectors. However, the shear behavior is relatively insensitive to variations in the channel thickness and bolt grade. Based on regression analysis, a load-slip mechanical model has been proposed. This model accurately describes the mechanical properties of this type of shear connector, providing a theoretical foundation for the application of demountable composite beams.

Pull-out strength of thin perfobond connectors and C-ties in steel-concrete-steel sandwich composite structures

Due to the remarkable mechanical property, short construction period, and labor-saving features, steel-concrete-steel (SCS) sandwich composite structures are widely used in assembled buildings, modularized immersed tunnels, and bridge cable pylons. In SCS sandwich structures, sufficient pull-out resistance in connectors is necessary to effectively prevent outward buckling of the outer steel faceplates. However, the existing connectors remain deficient in terms of load bearing capacity, ductility, and construction convenience. A novel type of connector named thin perfobond connector and C-tie (PBL-CT) was proposed to address these problems in this paper. While retaining the superior shear performance of traditional perfobond connectors (PBLs), the addition of C-ties in PBL-CTs enhances structural shear resistance. Through 18 monotonic pull-out tests, the pull-out performance of shallow-embedded thin PBL-CTs was investigated. Test results revealed that the primary failure mode of shallow-embedded thin PBLs was cracking of the surrounding concrete, with C-ties significantly improving the pull-out performance and shifting the failure mode to a combination of concrete breakout and perforated rib rupture. A nonlinear finite element (FE) model was developed and calibrated to conduct parameter analyses on concrete strength, embedment depth, and perforated rib parameters. This led to the establishment of a mixed failure model for shallow-embedded thin PBL-CTs. The ultimate pull-out bearing capacity was found to comprise two components: the pull-out resistance of the concrete cone and the shear resistance of the perforated rib. A regression-based prediction formula was derived, providing accurate and conservative predictions of the ultimate pull-out bearing capacity of shallow-embedded thin PBL-CTs.

Multitask Learning on Graph Convolutional Residual Neural Networks for Screening of Multitarget Anticancer Compounds.

Recently, various modern experimental screening pipelines and assays have been developed to find promising anticancer drug candidates. However, it is time-consuming and almost infeasible to screen an immense number of compounds for anticancer activity via experimental approaches. To partially address this issue, several computational advances have been proposed. In this study, we present iACP-GCR, a model based on multitask learning on graph convolutional residual neural networks with two types of shortcut connections, to identify multitarget anticancer compounds. In our architecture, the graph convolutional residual neural networks are shared by all the prediction tasks before being separately customized. The NCI-60 data set, one of the most reliable and well-known sources of experimentally verified compounds, was used to develop our model. From that data set, we collected and refined data about compounds screened across nine cancer types (panels), including breast, central nervous system, colon, leukemia, nonsmall cell lung, melanoma, ovarian, prostate, and renal, for model training and evaluation. The model performance evaluated on an independent test set shows that iACP-GCR surpasses the three advanced computational methods for multitask learning. The integration of two shortcut connection types in the shared networks also improves the prediction efficiency. We also deployed the model as a public web server to assist the research community in screening potential anticancer compounds.

«Путь духов – не обман»: «Дочь шаофу Цуя одаривает стихотворением Лу Чуна» (из «Записки о поисках духов», цзюань 16)

The article is devoted to the consideration of “The Daughter of Shaofu Cui Bestows a Poem upon Lu Chong”, a poem included into the anecdote “Lu Chong Marries a Deceased Woman” from the collection “In Search of the Supernatural” (the zhiguai xiaoshuo genre) by Gan Bao. The aim of the study is to identify the functional features, genre originality, and typological characteristics of this poem in the framework of the anecdote and the collection. The scientific novelty is determined by the fact that this poem has not been comprehensively analyzed yet. The line-by-line analysis of the poem, which constitutes the core of this article, is based on our own interlinear translation. By analyzing the poem, we have revealed its compositional features, commented on the images, outlined its motifs and types of connections between the motifs, formulated the themes, defined the idea. In addition, we have determined the genre of the poem, a series of typological features that unite this poem with other works of the same genre, and also the semantic and functional load of the poem in the context of the entire collection. The results have shown the following: first, “The Daughter of Shaofu Cui Bestows a Poem upon Lu Chong” is a literary message (epistle; letter) zeng, to be more precise – a literary appeal. Second, as it is not only one of the first messages, but also one of the first love messages in the history of Chinese literature, it allows us to make some generalizations on the specificity of the poetic [love] message in Chinese literature at the stage of its formation. Third, this small poem, an inserted element in fact, is subordinated to the general task, declared by the author in the preface, and it fully copes with this task.

Structural performance of precast concrete sandwich panels with bolt-steel plate connection subjected to axial loading

A new precast concrete sandwich panel with glass fiber-reinforced polymer connectors was proposed, utilizing bolt-steel plate connections. A compressive experiment was carried out to investigate the performance. The main damage was concrete crushing in the bolt connection region, at the panel bottom, and above the joint. The connector type, solid concrete rib, slenderness ratio, and thickness affected the failure mode and bearing capacity. The use of GFRP connectors and solid concrete ribs enhanced the ultimate bearing capacity and stiffness of the panels while reducing the lateral deflection. Higher slenderness ratios leading to reduced axial bearing capacity and increased lateral deflection. Finally, the results of the existing empirical calculation formulae were compared with experimental ones, and they were overly conservative. A new formula for predicting the bearing capacity was proposed, and the difference percentages between the proposed formula and experimental results were −0.4 %–2.8 %, which was the most accurate prediction formula.

Seismic performance of precast UHPC pipe pile with two pile-cap beam connection types: An experimental and numerical study

To develop an effective pile foundation scheme for earthquake-prone regions, this study introduces a novel pile structure that integrates ultra-high-performance concrete (UHPC) with traditional prestressed high-strength concrete (PHC) pipe piles. The research focuses on assessing the impact of various connection forms between the pile and cap beam on the seismic performance of bridge substructures. Two 1/3-scale specimens were meticulously designed and tested: one featuring a cast-in-place (CIP) connection and the other incorporating precast assembly (PA) connection between the pipe pile and cap beam. Cyclic loading tests were conducted to evaluate the failure mode, lateral capacity, ductility, energy dissipation ability, residual displacement, rebar strain, curvature distribution and rotation of UHPC pipe piles with the two connection forms. The results indicate that the specimen with a CIP connection exhibits a higher horizontal load capacity and stronger energy dissipation ability, while the specimen with the PA connection displays superior self-centering ability, increased ductility, and causes less damage to the cap beam. Finally, finite element models were developed to analyze the effects of design parameters on the seismic performance of the pile connected by the two methods. This research may provide valuable design guidance for incorporating UHPC in pile foundations. To facilitate its practical implementation in engineering projects, further theoretical and experimental research is recommended in this paper.

Correlated variability and its attentional modulation depend on anatomical connectivity

Visual cortical neurons show variability in their responses to repeated presentations of a stimulus and a portion of this variability is shared across neurons. Attention may enhance visual perception by reducing shared spiking variability. However, shared variability and its attentional modulation are not consistent within or across cortical areas, and depend on additional factors such as neuronal type. A critical factor that has not been tested is actual anatomical connectivity. We measured spike count correlations among pairs of simultaneously recorded neurons in the primary visual cortex (V1) for which anatomical connectivity was inferred from spiking cross-correlations. Neurons were recorded in monkeys performing a contrast-change discrimination task requiring covert shifts in visual spatial attention. Accordingly, spike count correlations were compared across trials in which attention was directed toward or away from the visual stimulus overlapping recorded neuronal receptive fields. Consistent with prior findings, attention did not significantly alter spike count correlations among random pairings of unconnected V1 neurons. However, V1 neurons connected via excitatory synapses showed a significant reduction in spike count correlations with attention. Interestingly, V1 neurons connected via inhibitory synapses demonstrated high spike count correlations overall that were not modulated by attention. Correlated variability in excitatory circuits also depended upon neuronal tuning for contrast, the task-relevant stimulus feature. These results indicate that shared variability depends on the type of connectivity in neuronal circuits. Also, attention significantly reduces shared variability in excitatory circuits, even when attention effects on randomly sampled neurons within the same area are weak.

Surgical Repair of Total Anomalous Pulmonary Venous Connection into the Superior Vena Cava: A Case Report.

Total anomalous pulmonary venous connection is a rare congenital anomaly that has four anatomical subtypes. In the supracardiac type, the common pulmonary vein confluence usually drains into the left innominate vein via a vertical vein; however, it may drain into the superior vena cava. Herein, we present a successful surgical repair of a rare type of total anomalous pulmonary venous connection in which the common pulmonary vein confluence was draining directly into the superior vena cava without a vertical vein.

Do government environmental target constraints break the political resource curse? --A study on political connections and firm green innovation

This study combines government environmental target data (2003–2015) with green innovation among listed firms of China. After investigating the relationship between political connections and firm green innovation, we focus on whether government environmental target constraints can break the political resource curse and enhance green innovation. The findings suggest the existence of a political resource curse in firm green innovation. However, government environmental target constraints effectively mitigate this curse, increasing the quantity of green innovation in firms with political connections but at the expense of a decline in quality of green innovation. We further conduct a robustness analysis using data from 2003 to 2021, and the research findings remain consistent. Mechanism analysis indicates that government environmental target constraints effectively boost the quantity of green innovation in politically connected firms by reducing rent-seeking costs and increasing R&D subsidies. Simultaneously, government environmental target constraints amplify financial constraints, subsequently squeezing high-quality inputs for green innovation and resulting in a decline in quality. Furthermore, the intensity of government environmental regulation influences the relationship between political connections and green innovation in a non-linear way. When the intensity of government environmental regulation is high, it motivates politically connected firms to increase the quantity of green innovation but at the cost of reduced quality. Heterogeneity analysis also reveals diverse impacts of government environmental target constraints on green innovation in firms with political connections, considering factors such as levels and types of political connections, green innovation, social attention, industries, regional economic growth pressure, and market conditions.

Characterization of different longitudinal shear transfer mechanisms for profiles embedded in concrete walls

Concrete walls or columns reinforced by one or multiple embedded steel profiles have gained popularity due to their improved strength, ductility and energy dissipation capacity. However, certain gaps in information are remaining in the available standards regarding the design of such non-conventional reinforced concrete systems. In particular, a proper characterization of the longitudinal shear transfer properties at the steel-concrete interface is required for a reliable design. Although sufficient information is available regarding mechanical connectors like shear studs, detailed information is required for any other types of mechanical connectors such as welded steel plates or for configuration without mechanical connectors. Moreover, even for cases with mechanical connectors, the orientation of the profile – and hence the distance to the face of the concrete – and the tying system can have a significant influence on the load transfer mechanisms. To this purpose, this article presents the outcomes of a set of push-out tests with the objective of comparing the force transfer mechanisms from the steel profile to the surrounding concrete wall for different types of interfaces. 13 tests specimens are investigated, with flexible (shear studs) and/or rigid (steel plates) shear connectors, considering different orientations of the profile and tying mechanisms, as well as a comparison with profiles without mechanical connectors. Based on the test results and subsequent analytical assessment, relevant conclusions are drawn regarding the longitudinal shear transfer at the steel-concrete interface. If necessary provisions are followed, welded steel plates prove to be an effective alternative to the shear stud connectors in terms of connector strength. The orientation of the embedded steel profile, consequent position of the mechanical connectors and their distance to the concrete face are observed to have a significant influence on the compression strut evolution, which therefore dictates the necessity (or not) of horizontal confinement or ties. Furthermore, combining the shear strength offered by different types of mechanical connectors and the steel-concrete bond offer a precise estimate of the longitudinal shear strength and therefore indicates towards the conservative nature of the design provisions suggested by the available standards.

Experimental and numerical study on behavior of demountable shear connectors in sustainable reinforced concrete beam-slab

Developed herein is a novel fully demountable shear connector, P-DBSCs (Demountable Bolted Shear Connectors with End Plate), aimed at enhancing the economic and environmental advantages of traditional buildings undergoing disassembly and reconstruction. This work numerically and experimentally assessed the shear performance of P-DBSCs via seven push-out tests and finite element simulations. Results revealed a uniform failure mode across seven specimens characterized by bolt fractures, absent of significant beam or slab cracking, evidencing remarkable post-failure demountability. According to the assessments of the specimens' force state, encompassing Digital Image Correlation (DIC) and anti-lifting capacity analyses, established that specimens fitted with larger bolts maintained better integrity and the concrete beam is under compression state, with lifting displacements remaining below 1.2 mm. Further, a verified finite element model's parameter study explored the influences of factors such as slab concrete strength, channel spacing, steel box thickness, channel thickness, steel box strength, and the diameter and strength of bolts on the shear performance of these connectors, finding these attributes to significantly affect shear performance within specific ranges, except for the slab concrete strength, to which shear performance displayed lesser sensitivity. Regression analysis facilitated the proposition of a mechanical constitutive model and stiffness degradation model for this connector type, validated through correlation with experimental results. These models provide a solid theoretical foundation for implementing demountable reinforced concrete (RC) beam-slab systems.

Examination of Various Abutment Designs Behavior Depending on Load Using Finite Element Analysis.

Studies on dental implant abutments' geometric design and material selection offer significant innovations and results. These studies aim to improve the abutments' functionality and aesthetic performance, minimize microcavities' formation, and ensure implant-supported prostheses' longevity. For example, CAD-CAM fabricated custom abutments have been found to produce a better marginal fit and fewer microgaps than standard abutments. In an in vitro study, transepithelial abutments offered lower microgap values than titanium-based abutments and provided a better fit at the implant-abutment interface. It is known that studies to improve mechanical and biological performance with Polyether Ether Ketone (PEEK) material have been addressed. New materials such as PEEK and zirconia have offered significant advantages in biocompatibility and aesthetics. Along with those studies, different abutment designs are also important. Abutment geometry is optimized to improve stress distribution and minimize peri-implant bone loss. In implant and abutment connections with different angles, mechanical life performances may vary depending on static and dynamic load. These studies emphasize the importance of material research on different types of connections to improve dental implants' durability, homogeneous load distribution, and reliability. The abutment parts used in implant treatment are insufficient to distribute the load homogeneously against chewing pressure due to their materials and geometry. Non-uniform load distribution damages the abutment and the prosthetic crown, accelerating the wear process. This study aimed to create different abutment designs to improve dental implants' biomechanical performance and longevity. This study aimed to increase the mechanical durability of the implant-abutment connection by reducing stress concentrations in response to masticatory compression on the abutment in different directions and forces and to guarantee the long-term success of the implant system by providing a more homogeneous stress distribution. It aimed to apply different forces in the axial direction to these models in a simulation environment and to calculate and compare the deformation and stress load distribution. As a method, three-dimensional models of the parts used in implant treatments and forming the implant system were designed. Different abutment designs were created with these models. Taking the current material values used in implant treatments as a reference, finite element analysis (FEA) was performed by applying different axial loads to each implant system model in the ANSYS software (version 24.1). Comparative analysis graphs were prepared and interpreted for the stress values obtained after the applied load. This study evaluated the mechanical performance of different abutment models (A, B, C, D, and E) under a 100 N load using the Kruskal-Wallis test. The Kruskal-Wallis test showed significant differences between the groups (p < 0.001). The greatest difference was observed between models E and A (q' = 6.215), with a significant difference also found between models C and A (q' = 3.219, p < 0.005). Regarding stress values, the highest stress on the abutment was observed in Model B (97.4 MPa), while the lowest stress was observed in Model E (9.6 MPa). The crown exhibited the highest stress in Model B (22.7 MPa) and the lowest in Model E (17.3 MPa). The implant stress was highest in Model C (14.8 MPa) and lowest in Model B (11.3 MPa). The stress values for the cortical bone and cancellous bone were quite similar across the models, showing no significant differences. These findings indicate that the abutment design and material selection significantly impact mechanical performance. Among the implant systems created with five different abutment models, in which the existing abutment geometry was also compared, homogeneous and axial distribution of the load on the abutment was achieved, especially with viscoelastic and surface area increased abutment designs. Clinically, the inadequacy and limited mounting surface or geometry of the abutments used in today's implant treatment applications have led to different design searches. It was concluded that the designs in this study, which are considered alternatives to existing abutment models, contribute positively to the mechanical life of the abutment material, considering the von Mises stresses and directions. This study brings a new perspective to today's practices and offers an alternative to treatment practices.

Study and Application of Fine Dissection Methods for Inter-river Sands in Large Shallow River-controlled Delta Plains

Applying the data of coring wells and logging curves of dense well network, identifying the sedimentary sands of different river systems and contemporaneous periods with the methods of standard layer approximation control and comparison of reference layer combinations, establishing a set of logging phase models of inter-river sands, and using the models as a guideline for micro-phase identification, we have studied the distribution and combination characteristics of the micro-phase sands of the inter-river sand bodies, as well as the type of connectivity with the sand bodies of the river and the relationship, and clarified the distribution characteristics and residual oil distribution of the sand bodies of the inter-river sands. The characteristics of different types of sand body movement and residual oil distribution were clarified, effective dredging methods were proposed, and measures such as oil testing and fracturing were taken, which played an important role in guiding the adjustment and dredging of oil fields in the late stage of high water content.

Micromechanical analysis of magnetoelectric coupling of composites containing nonlinear magnetostrictive and piezoelectric constituents

This paper is a reformulation of the simplified unit-cell and Mori-Tanaka micromechanics theories in their applications to nonlinear magnetoelectric analysis of two-phase composite materials with 0–3, 1–3, and 2–2 connectivity types, respectively. We elucidate the similarity between the two models insofar as concentration-factor matrices are concerned. The representations of the bulk magnetostrictive and piezoelectric phases are based on nonlinear constitutive equations. Due to material nonlinearity, the mathematical frameworks are accomplished via incremental formulation that provides a system of linear algebraic equations at each increment which is obviously a great advantage over nonlinear one. The derived nonlinear composite constitutive relations that govern the hysteresis behavior of composites are implemented to study the composite composed of Terfenol-D and PZT constituents. The responses of this composite to a complete cycle of magnetic field are shown and the micromechanics predictions are compared in light of existing experimental data.

Experimental and Theoretical Study on the Interface Mechanical Performance of Aluminum–Timber Composite Connections

The interface mechanical performance between aluminum alloy and timber is the key to ensure that the two work together. In this study, 11 group connection performance tests were carried out to investigate the influence of connection type (shear bolt connection, epoxy resin adhesive connection, and mixed connection), number and spacing of bolts, thickness, and length (the area of incidence of the adhesive in the structure) of epoxy resin adhesive on the interface shear-resistant capacity of aluminum–timber composite connections. The shear performance of the three kinds of connections were studied via finite element analysis, and the calculation formula for interface shear-resistant capacity of the aluminum–timber composite connection was proposed based on the bond-slip mechanism of adhesive. The analysis results indicate that the mixed connection can avoid the brittle failure characteristics of the shear bolt connection and the epoxy resin adhesive connection, and the shear-resistant capacity is increased by 45.6% and 14.7%, respectively. The results of the calculation formula for interface shear-resistant capacity are in good agreement with the experimental results, indicating that it is suitable for the aluminum–timber composite connection.

Impact resistance and performance of precast shear walls with various connections under axial and lateral loads

This study conducted pendulum impact tests on three precast concrete (PC) shear wall specimens with various connection types and one cast-in-situ reinforced concrete (RC) shear wall specimen to investigate their behavior under out-of-plane impact loads at a consistent axial compression ratio. The study reported observations on failure patterns, the progression of cracks, the dynamics of impact force over time, relationships between axial force and vertical displacement, deformation behavior, and the strains in concrete and rebars. Through comparative analysis with similar PC columns, the influence of various connections on the impact resistance is analyzed for both shear walls and column specimens. It was found that all PC specimens showed flexural failure modes akin to those of the RC specimen, yet with more extensive cracking and lower stiffness. PC specimens with grouted sleeve connections demonstrated satisfying impact resistance that emulates the performance of cast-in-situ walls. Specimens with grouted corrugated metallic duct connections demonstrated obvious localized damage. Eventually, the study proposes a novel method for rapidly evaluation of the impact resistance of concrete shear walls.