Search

Connections play a vital role in the transfer of lateral forces and energy dissipation in cross-laminated timber (CLT) structural systems. However, moisture exposure (e.g., rain during or after construction) can affect the durability of CLT structural members and their connections due to the hygroscopic nature of wood. Limited knowledge exists on the moisture performance of CLT connections. Therefore, in this study, a CLT shear wall-to-diaphragm angle bracket connection was exposed to simulated rain and relative humidity cycling (wetting) and subsequent redrying followed by mechanical loading cyclic testing. Four wood species (Douglas-fir, southern pine, Norway spruce, and spruce-pine-fir) and three wetting durations were applied to understand the effect of moisture intrusion on the connection performance, which was evaluated in terms of strength, stiffness, and energy dissipation. Two force–displacement backbone models were fitted to the experimental data. The results suggest a statistically significant increase (9%–15% for different species) in the peak strength and no change in the stiffness and energy dissipation capacity after the wetting and redrying cycles. However, additional studies should be conducted to gain further insight into the observed increase in load-carrying capacity. Additionally, the authors caution against considering any strength increase until further studies are conducted. [ABSTRACT FROM AUTHOR]

Wood-based composites (WBCs) are engineered wood products that are commonly used in the building and furniture industries. Most research on their durability has relied on internal bond testing, bending strength properties, or damage observations. An alternative property with potentially more information is fracture toughness. Here, fracture toughness was continuously measured during crack propagation for three different composites—oriented strand board (OSB), medium density fiberboard (MDF), and particleboard (PB). The resulting plots for fracture toughness as a function of crack growth are known as the material's R curve. To assess the role of temperature on WBC durability, R curve experiments were repeated at 10 different temperatures from 20 to 200 °C. Trends in experimental results could be described by a trilinear model. OSB and MDF toughness initially increased with temperature and then decreased above 80 °C. The toughness of PB, which was made with a different resin, remained constant or decreased slightly until decreasing faster above 140 °C. Both the resin type and composite structure affected the results. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) is an engineered wood product offering several advantages for wood utilization in midrise and tall buildings. However, moisture intrusion poses significant risks since it can affect the durability of CLT structural members and their connections. There has been much research on connection performance to understand their seismic response. However, the impact of moisture on the performance of CLT connectors is less understood. Cyclic tests were conducted on a series of CLT shear wall-to-diaphragm L-bracket (angle bracket) connections after subjecting them to a wetting and redrying cycle. The study includes three exposure durations and four wood species (Douglas fir, Southern yellow pine, Norway spruce, and spruce-pine-fir) to investigate the effect of moisture exposure on the connection performance. The performance was characterized in terms of strength, stiffness, and energy dissipation. In addition, two existing engineering force-displacement models were fitted to the experimental data. Results indicate that the changes due to wetting and redrying cycling were not statistically significant for the load-carrying capacity and stiffness. In contrast, a statistically significant decrease in the total energy dissipation capacity was observed. [ABSTRACT FROM AUTHOR]

With the rapidly growing interest in using structural timber, a need exists to inspect and assess these structures using non-destructive testing (NDT). This review article summarizes NDT methods for wood inspection. After an overview of the most important NDT methods currently used, a detailed review of Ground Penetrating Radar (GPR) and Ultrasonic Testing (UST) is presented. These two techniques can be applied in situ and produce useful visual representations for quantitative assessments and damage detection. With its commercial availability and portability, GPR can help rapidly identify critical features such as moisture, voids, and metal connectors in wood structures. UST, which effectively detects deep cracks, delaminations, and variations in ultrasonic wave velocity related to moisture content, complements GPR's capabilities. The non-destructive nature of both techniques preserves the structural integrity of timber, enabling thorough assessments without compromising integrity and durability. Techniques such as the Synthetic Aperture Focusing Technique (SAFT) and Total Focusing Method (TFM) allow for reconstructing images that an inspector can readily interpret for quantitative assessment. The development of new sensors, instruments, and analysis techniques has continued to improve the application of GPR and UST on wood. However, due to the hon-homogeneous anisotropic properties of this complex material, challenges remain to quantify defects and characterize inclusions reliably and accurately. By integrating advanced imaging algorithms that consider the material's complex properties, combining measurements with simulations, and employing machine learning techniques, the implementation and application of GPR and UST imaging and damage detection for wood structures can be further advanced. [ABSTRACT FROM AUTHOR]

Connections in mass timber structural systems transfer lateral forces from mass timber elements such as shear walls to floor diaphragms. Cross-laminated timber (CLT) is a prominent engineered mass timber material used to manufacture walls and floor assemblies. Fire performance research of CLT walls and floors has been abundant in recent years in an effort to develop an understanding of the performance of structural members under fire. Some fire-protected structural elements, including connections, may not be directly exposed to flames in a fire event but will experience elevated temperatures. There is limited research on elevated temperature performance of CLT connections, and consequently a lack of understanding of their fire performance in CLT structures. To aid in bridging this knowledge gap, in this study a series of cyclic shear tests were conducted on a CLT wall-to-floor bracket connection assembly to characterize thermal degradation according to a matrix of 28 exposure duration–temperature combinations. Two different methods were employed to develop force-displacement backbone models from the experimental hysteresis data. Models from both methods indicate an overall degradation of the connection performance in terms of load carrying capacity, elastic stiffness, ductility, and energy dissipation with increasing exposure to elevated temperatures. [ABSTRACT FROM AUTHOR]

This research investigated the mechanical characteristics of cross-laminated timber (CLT) connections fastened with structural wood screws, also known as self-tapping screws (STS). The CLT connection assemblies were toe-screwed (TS) at 45° and cyclically tested in tension and in-plane shear to evaluate the failure modes and applicability as seismic connections in CLT shear walls. The connection assemblies were representative of full-scale CLT shear walls connected to CLT floors as often seen in platform construction. Toe-screwed CLT connections exhibited screw fracture, head pull-through, and pinched hysteresis loops. Mechanical connection properties and backbone curves were extracted for comparison with design estimates. A head pull-through design method was developed, which predicted peak strength within 5% of test results. Connection parameters for ASCE/SEI 41 idealized-component curves were presented for use in performance-based design nonlinear-static pushover analysis. Combining the presented ASCE/SEI 41 parameters with the proposed design method and test results provides a simple and reasonably accurate nonlinear toe-screwed connection response curve. Partially threaded washer-headed screws were found to be superior to fully threaded screws in seismic applications due to their 15 times greater ultimate deformation capacity, substantially greater energy dissipation, similar peak strength, and similar elastic stiffness. However, the yield strength of partially threaded STS was found to be 48% of the yield strength of fully threaded STS. [ABSTRACT FROM AUTHOR]

Connections in mass timber structural systems are critical for transferring lateral forces from mass timber elements such as shear walls and diaphragms. Cross-laminated timber (CLT) is a prominent mass timber material used to manufacture these wall and floor assemblies. Although research exists that investigated the fire performance of CLT walls and floors, very little investigation has been devoted to the thermal performance of the connection systems themselves. This void in the data and knowledge surrounding CLT connections is an impediment for modeling the elevated temperature performance of CLT structures. Therefore, a series of shear tests were conducted on a CLT L-bracket connection assembly to characterize the thermal degradation of peak loads and initial stiffness as a function of exposure duration at a given temperature. A total of 116 specimens, including four control specimens, were tested according to a matrix of 28 exposure duration-temperature combinations. Two analytical models are developed to explain the thermal degradation—one assuming a mechanism based on first-order kinetics and the second using a statistical regression. The results of this work indicate that the degradation of peak load and initial stiffness with respect to exposure duration occurred at a linear rate and depended on temperature, according to the Arrhenius activation energy theory. This research is a step toward a holistic evaluation of elevated temperature modeling of CLT structures. [ABSTRACT FROM AUTHOR]

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes. [ABSTRACT FROM AUTHOR]

Mass timber construction has seen a growing interest in North America and worldwide. In the US, code provisions allow mass timber buildings to be up to 82 m tall, but with floor slabs requiring a noncombustible, usually cementitious, topping over mass timber panels (MTPs). Designing the MTP and concrete topping to act compositely can increase the strength and stiffness compared to noncomposite MTP floors. Several connections are available to create composite action between an MTP and a concrete topping, with self-tapping screws being the most widely considered practice. A new test fixture and testing method were developed to characterize connection properties and facilitate the selection of fasteners most suitable for developing composite action. Three conventional self-tapping screws were experimentally investigated at the single-fastener scale. The screws were subjected to withdrawal at 90° and 45° orientations to the interface plane between the MTP and concrete. Withdrawal from both the MTP substrate and concrete topping was investigated. Three MTP materials were tested: cross-laminated timber (CLT) consisting of two different wood species and a mass ply panel (MPP). Results demonstrated that the pullout failure of the screwhead from the concrete was the limiting failure mode. Comparisons were made between the experimental results and analytical models for screw withdrawal to assess the applicability of available models to the different MTPs. These models underestimated the capacity of the tested fasteners for all samples except for the fully threaded screws. [ABSTRACT FROM AUTHOR]

The quality of wood composites is dependent on the bondlines' performance and their moisture resistance. The effect of moisture intrusion into bondlines is the focus of this study. The strain profile in the bondline during loading was investigated and the effects of weathering on the bondline were quantified by digital image correlation (DIC), while load deflection data were collected from lap-shear tests (LShTs). A total of 75 LShTs were evaluated including four different adhesive types with Douglas-fir wood, out of which 39 served as controls and 36 as substrates for weathering. The effect of weathering on failure load was not statistically significant. Only the bonded surface and adhesive type have significant effects on failure load, as well as the three-way interaction between the bonded surface, adhesive, and weathering, as revealed by three-way analysis of variance (ANOVA). The average effective shear moduli for the weathered samples were significantly lower than those for the control samples. [ABSTRACT FROM AUTHOR]

Synthesis of nano-crystalline hydroxyapatite (HAp) from fish scale ( Catla catla ) was carried out by calcining of raw fish scale between 200 °C and 1200 °C. The synthesized powders were characterized using thermogravimetry – differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The crystallinity, crystallite size, strain and cell parameters of fish scale derived calcined powders and chemically synthesized HAp (S-HAp) powders were estimated from XRD data. The average crystallite size of fish scale derived HAp powder increased with increasing calcination temperature. The fish scale derived HAp (FSH800) and S-HAp, calcined at 800 °C, showed crystallite size of 30 nm and 60 nm, respectively. ICP-AES analysis revealed that the fish scale derived HAp powder calcined at 1200 °C (FSH1200) contain significantly high amount of magnesium and strontium ions compared to S-HAp. After sintering at 1200 °C for 1 h, the relative density of FSH1200 was 20% higher than that of S-HAp due to better sinterability as a result of its small crystallite size and the presence of trace elements. In vitro cytotoxicity studies performed using human osteoblast-like cells (MG63) and mouse osteoblast cell line (MC3T3-E1) demonstrated that fish scale derived HAp (FSH1200) is non-toxic. [ABSTRACT FROM AUTHOR]

Green building practices have created an opportunity for the forest products industry to become a leader in the creation of in- novative building products derived from renewable materials. In other industries, sandwich composites have proven to be efficient structures by meeting structural demands of traditional panel products while consuming less material. A prototype molded-core sandwich panel made of span-rated oriented strand board (OSB) facings and a bidirectional molded wood-strand core was produced. Critical mechanical properties were evaluated to determine the feasibility of this product for use in building applications. The goals of this study were to generate details on structural performance of the product, validate the design, and provide suggestions for future product development. Results indicate that this molded-core panel performs particularly well in flexure while connection properties had the largest scope for improvement. Sufficient performance was observed to validate the design, warranting production and testing of panels sized for end-use. Future product development should explore different connection systems, perform detailed engineering analyses of the mechanical properties necessary for complete structural design, and characterize physical properties of the panel. [ABSTRACT FROM AUTHOR]

This study explored the suitability of fracture toughness properties for durability assessment of wood composite panels by observing changes in fracture toughness during crack propagation following cyclic exposure to moisture conditions. The main objective was to develop a new method for ranking the role of adhesives in the durability of wood-based composites. This new approach was compared to conventional mechanical performance tests, such as observing strength and stiffness loss after exposure. Comparing changes in fracture toughness as a function of crack length after moisture cycling shows that this approach can distinguish different adhesive systems on the basis of their durability, while conventional tests fail in this regard. The most and least durable adhesives (polyvinyl acetate and phenol formaldehyde) could be distinguished based on steady-state toughness alone, but this was not the case for the performance of two other adhesives (emulsion polymer isocyanate and phenol resorcinol formaldehyde). Further analysis of experimental R curves (toughness as a function of crack length) based on kinetics of degradation was able to rank all adhesives confidently. Probably, the failure of conventional tests in this context is that they are based on initiation of failure, while the fracture tests require consideration of fracture properties after a significant amount of crack propagation has occurred. [ABSTRACT FROM AUTHOR]

Limited research exists on the deformation compatibility behavior of mass timber beam-to-column connections. Therefore, to investigate this behavior, large-scale experimental monotonic testing was performed on five different glue-laminated (glulam) beam-to-column connections. The purpose of this research was to create a better fundamental understanding of the deformation compatibility behavior of mass timber beam-to-column connections. Three connections were custom-designed connections, and two were pre-engineered connections. Specimens included the presence of cross-laminated timber (CLT) decking on the beam, as well as combined lateral and gravity loading. Monotonic tests pushed specimens to a target story drift of 7.2% at a rate of 0.51 mm/s. The data were analyzed, and the yield force, yield displacement, initial stiffness, secant stiffness, and connection classification (categorized as either rigid, semirigid, or flexible) were calculated for each connection. Per the connection classification methodology used, all connections were classified as flexible (simple) connections. However, the pre-engineered connections use substantially more screws and plates thereby increasing the cost and effort of installation. The results demonstrate that in some cases simple custom connections can have a larger yield force and initial stiffness than pre-engineered connections, and due to the reduction in number of screws, there was less damage within the connection at the completion of the test. The forces required to push connections to 2% drift all exceeded the lateral force capacity of the connections; however, all connections maintained load-carrying capacity throughout testing. [ABSTRACT FROM AUTHOR]

New building code changes enable mass timber panels (MTP), including cross-laminated timber (CLT), to be used in moderate and tall buildings as a floor system, usually with a concrete topping. A floor system of CLT composite with a reinforced concrete topping slab can provide increased stiffness and strength, making the system more advantageous. Present connection methods used to produce composite action within timber-concrete composites (TCC) have limitations when considering constructability or performance. This study presents experimental results from four (4) shear connectors for CLT-concrete composite floor systems, including three developed for this study. The connectors included self-tapping screws (STS) at 45-degrees, a modified lag screw with an integral plate washer that bears on the CLT surface at installation, a steel angle anchored only at the end of the span, and an inverted-T steel section with stem perforations. Different tests were performed on the different connectors including individual fastener tests, push-off group tests, and full-scale one-way bending tests. The push-off group tests showed that the proposed washer-screw exhibited higher stiffness and strength than a conventional STS. The full-scale one-way bending testing showed that the STS specimen exhibited the lowest strength of the alternatives. The inverted-T section exhibited the highest stiffness, while the other three connections had similar stiffness to the STS. [ABSTRACT FROM AUTHOR]

To quantify the postpeak residual capacity and to gain insights into the load transfer mechanism of a shear wall, nail connection tests were performed on salvaged connections after a monotonic shear wall test loaded up to peak load. Experimental results reveal that there is a loss of strength in most of the fasteners studied, indicating that almost all the fasteners contribute toward racking resistance of the wall. The maximum loss of strength was observed for the fastener in the uplift corner and for the fastener along the middle stud. Another area where fasteners exhibited a significant loss of strength was in plate connection located at the bottom plate. The performance of a shear wall can be enhanced by strengthening the two areas - uplift corner and bottom plate. [ABSTRACT FROM AUTHOR]

The deformation compatibility behavior of glue-laminated (glulam) beam-to-column connections is not yet well understood. To investigate this behavior, 10 specimens representing five different glulam beam-to-column connections were tested under lateral cyclic loading. Three of the connections were custom-designed connections and two were pre-engineered connections. Specimens were large-scale glulam beam-to-column connections, and testing included combined gravity and lateral loading as well as the presence of a cross-laminated timber (CLT) deck. Connection characteristics such as yield force, initial stiffness, secant stiffness, and energy dissipation were calculated and compared across connections as well as observations made during testing. Results from the experimental testing indicated that pre-engineered connections demonstrated overall better performance than the custom connections. Pre-engineered connections had the largest remaining secant stiffness by the end of the loading protocol, greater energy dissipation, and larger average yield forces than the custom connections. Although all connections tested exceeded their lateral design capacities at drift levels less than 2% drift, all connections maintained load-carrying capacity throughout testing. [ABSTRACT FROM AUTHOR]

As oriented strand board (OSB) increases in use, improving the mechanical properties is of importance. Improved in-plane shear properties will allow for more efficient use as well as open up other opportunities in engineered wood products with high shear stresses. Based on classical laminated plate theory, composite laminates with laminate alignment patterns produce higher in-plane shear modulus and strength compared with typical alignment. Oriented strand board was manufactured 13.3-mm thick with and alignment patterns, and in-plane shear, bending, nail connection, and small-scale shear wall properties compared to commercial OSB. Results showed a 24% increase in shear modulus for the alignment when compared with the alignment using a method similar to a standard in-plane shear test. Results also show 10% reduction in bending modulus of elasticity in the parallel direction. Small-scale shear wall tests were insensitive to changes of in-plane shear properties. Lateral nail connection tests showed no reduction in connection yield load, implying that these panels can be used in similar applications without affecting connection properties. [ABSTRACT FROM AUTHOR]

Mass ply panel (MPP) is a new mass timber product that was recently introduced for structural applications in buildings. Although there have been several studies on characterizing the mechanical properties and structural performance of MPP, there is a lack of understanding regarding in-plane shear properties of the panels. More intensive studies should be done for MPP to provide a comprehensive understanding of its behavior. This paper presents an experimental study to characterize the effective in-plane shear modulus and shear strength of MPP in the major strength direction of the panel. Two experiments, including multiple span-length center-point bending tests and a novel large-scale shear test, were conducted. The test results were presented and compared with previous studies and the manufacturer's product report. The new test proposed for shear strength characterization has the potential to be an industry standard for mass timber panels. [ABSTRACT FROM AUTHOR]

In the last several decades, there has been significant growth in research and development activities in nanomaterials. Nanotech has been used to improve the quality of several materials, including wood and polymer composites, for their application in various fields. Nanofillers, including metal particles, nano oxides, pyrogenic silica, and carbon black, have been employed as polymer additives. However, the value of natural, low-cost, and plentiful clay materials such as nanoclay becomes more apparent as environmental regulations and consumer awareness become more rigorous. This literature outlines the role of nanoclay on polymer composites, especially in the case of thermosetting resins, including epoxy, polyester, urea-formaldehyde, and phenol-formaldehyde resins. The current article is intended to provide a comprehensive source of recent studies and literature on nanoclay as filler, its classification, polymer modification processes using nanoclay, and comparing the performance of different thermosetting polymers based on their fabrication methods through physical and mechanical properties. [ABSTRACT FROM AUTHOR]

• Cross-laminated timber rocking walls dissipate energy through connection damage. • Slip-friction connections were originally developed for steel structures. • The SFC system was designed as a hold-down in a self-centering CLT rocking wall. • Quasi-static, cyclic tests with SFC connections showed elastic-plastic behavior. • Passive damping was close to typical idealized friction hysteresis models. Cross-laminated timber (CLT) rocking walls limit internal building forces and dissipate seismic energy mostly through severe connection damage and related wood crushing. While collapse-prevention and life-safety performance can be achieved, the connections and CLT walls are permanently damaged and may be unreliable for resisting aftershocks. Slip-friction connections (SFCs), also known as slotted-bolted connections, are highly resilient passive dampers originally developed for steel structures. As part of a thorough research program to apply SFCs to CLT rocking walls, connection tests were conducted to better understand a novel application of multiple modern timber technologies. The research objectives were to design and test a slip-friction connection connected to cross-laminated timber with inclined self-tapping screws (STS) to determine the stiffness and passive damping properties of the assembly. The SFC system was designed for use as a slip-friction hold-down in a self-centering CLT rocking wall system. A series of quasi-static, cyclic axial tests with slip-friction connections was shown to impart ductile and elastic–plastic characteristics to an otherwise non-ductile CLT connection. Because the timber connection forces were limited below the STS yield strength by the slip-friction connectors, no wood damage was observed during SFC sliding. Compared to other sources, passive damping was found to be excellent and close to typical idealized friction hysteresis models. The slip-friction connections are a unique design using an efficient CLT to SFC connection, with no slack, that performs consistently after consecutive tests. Additionally, cursory equivalent-viscous-damping ratios were extracted for the elastic range of the STS to steel connection for small amplitude excitations below the slip force threshold. [ABSTRACT FROM AUTHOR]

Over the past decade, cross-laminated timber (CLT) panels have gained popularity worldwide. To achieve larger spans and to increase the resistance to diaphragm seismic and wind forces to be transferred through CLT floor or roof systems, CLT-concrete composite (CCC) floors have been developed as an alternative. While significant testing has been performed under gravity loading, limited experimental data exist on the in-plane performance of CCC systems. This study presents results from an experimental program designed to characterize the in-plane shear behavior of CCC diaphragm connections using different CLT to concrete screw connector orientations in a test setup that simulates the expected seismic load path in diaphragms for platform-type construction. Tested variables include concrete slab thickness, composite screw angle, and single spline connection systems consisting of nails or screws. Experimental results and observed damage progression from cyclic testing are presented and discussed. Results indicate that CCC systems achieved increased stiffness and strength values when compared to bare-CLT systems, but slab thickness did not influence the strength and stiffness of the system for the load paths simulated. Additionally, CCC floor systems with 45° composite screw connectors displayed increased strength but overall similar stiffness values when compared to the CCC systems with 90° composite screws. The results provide useful engineering parameters, such as elastic stiffness, peak load, displacement capacity, and ductility ratios that can be used in the development of codified design parameters or in performance-based designs. [ABSTRACT FROM AUTHOR]

Mass plywood panel (MPP) is a veneer-based engineered wood product that recently was introduced in the mass-timber construction industry. Preliminary studies show that MPPs can be a preferred construction material for shear walls, floor diaphragms, and roof assemblies. However, no design guide exists regarding the use of MPPs as structural elements. This is compounded by a lack of engineering properties and parameters needed beyond the generic values provided in the product report. To assess the engineering properties and provide a benchmark dataset, a comprehensive experimental testing program characterized the performance of MPPs in flexure, in-plane shear (parallel to major strength direction), compression, and tension. Additionally, the characteristic values of MPPs were derived based on the test results to provide an initial indication of design values of MPPs. The test results presented in this study provide a fundamental basis for the development of a design guide for MPPs. [ABSTRACT FROM AUTHOR]

An optimization problem was developed by using a genetic algorithm to select wavelengths for establishing multivariate calibration models based on partial least squares (PLS) regression. Two near infrared (NIR) data sets represented by untreated and second derivative spectra were used to predict Eucalyptus globulus pulp yield. The optimization process was run with the number of variables (i.e., wavelengths) varied from 10 to 100 to determine the optimum wavelengths and number of latent variables for PLS regression model. A linear function of R-squares for calibration and prediction sets was utilized as the objective function of the optimization problem. The optimum wavelengths selected by genetic algorithm helped to considerably improve the performance of the PLS regression model, not only for the calibration sets but also for the prediction sets. The optimum number of latent variables varied over a wide range, from the maximum allowed (20) to a lower limit of six. Representative wavelengths for each data set were also statistically determined and assigned to corresponding wood components through a band assignment process, which showed strong agreement. [ABSTRACT FROM AUTHOR]

A full-scale 2-story mass timber building was tested on the University of California San Diego Natural Hazards Engineering Research Infrastructure (UCSD-NHERI) uniaxial shake table during the period from June 2017 to September 2017. The main objective of the experimental program was to test the performance of mass timber building designs with different seismic lateral force–resisting systems. The focus of this study is on a building configuration designed using self-centering post-tensioned cross-laminated timber (CLT) rocking walls with U-shaped steel flexural plate energy dissipators. The shake-table tests were designed to subject the building to a series of earthquake ground motions of increasing intensity, ranging from a service-level earthquake to 1.20 times the maximum considered earthquake intensity. Between each ground motion, low-amplitude white-noise excitations were applied to the building, which responded as a quasilinear system. In this paper, two output-only operational modal analysis methods are used to estimate the modal parameters (frequency, damping, and mode shapes) based on acceleration data collected during the white-noise shake-table tests. The correlations of observed damage and repairs performed during the experimental program with changes in estimated modal features are reported. The modal parameters estimated from the testing program are also compared with a linear finite-element model that is used to validate the modal identification results and study the performance of the two system identification methods for CLT rocking structures. [ABSTRACT FROM AUTHOR]

This paper presents the behavior of floor diaphragms of a shake-table experiment of a full-scale 2-story mass-timber building structure. The structure consists of glued-laminated timber beams and columns, and floors and walls were designed and built making use of cross-laminated timber panels. Two different floor systems were designed, where the roof consists of a topped cross-laminated timber (CLT)-concrete composite system, and the floor level consists of untopped CLT panels connected with plywood single-surface splines. The CLT floor systems were designed to remain essentially elastic over the whole series of shake-table tests, which included testing of three lateral force–resisting systems tested at three different seismic intensity levels (service level, design basis, and maximum considered earthquake) for a total of 34 shake-table earthquake tests. Results from the testing indicate that CLT diaphragms designed to remain essentially elastic based on basic principles of structural mechanics and existing test data can achieve desired seismic performance objectives. In addition, sources of overstrength in certain elements of the diaphragm need to be explicitly considered for a holistic diaphragm design. [ABSTRACT FROM AUTHOR]

Consistent with the diagnosis-to-randomization analysis, patients with DS <=7 days were more likely to have adverse disease characteristics (e.g. double-hit lymphoma, bulky disease, high LDH, and fever) than those with longer DS (Table 1). Novel treatment regimens combining chemotherapy with targeted agents are being developed for diffuse large B-cell lymphoma (DLBCL). Our findings suggest that treatment delay due to biomarker testing does not affect outcome on this model, and should not preclude enrollment of patients into clinical trials. In step 2 of the 2-step analysis model, median SR time in patients with more aggressive disease (patients with DS <=7 days) was 7 days (range 1-26 days). [Extracted from the article]

Timber–concrete composite (TCC) floors exposed to fire experience charring and thermal degradation of timber, leading to a reduction in load-carrying capacity. Finite element (FE) modeling supplements data from experimental fire testing and allows for fast and economical investigation of additional design parameters. This research presents fire test results of three large-scale TCC floor specimens and development of an FE modeling methodology for TCC floors in a fire. TCC floors constructed with nail-laminated timber, cross-laminated timber, or mass ply panel, with truss plates or angled screws as shear connectors, are loaded with a uniformly distributed service-level live load and exposed to the ASTM E119-20 standard fire curve. A 2D FE modeling methodology is presented and benchmarked against the test data. The methodology integrates sequentially coupled thermal-structural analyses, which make use of temperature-dependent thermal and mechanical properties of timber and concrete. The deflection and failure times of the FE models are benchmarked against test data. Connector forces from FE models show that shear connectors remain elastic throughout the fire exposure. FE results indicate that the load-carrying capacity is dependent on tensile stress redistribution to the uncharred timber section. The FE modeling methodology effectively calculates the mechanical and fire behavior of TCC floors and highlights limits of the applicability of analytical design methods. [ABSTRACT FROM AUTHOR]

Context: There is scarcity of data on thyroid function abnormality in COVID-19 patients in world literature. Aims: The objective of this study was to assess thyroid function tests in hospitalized patients of COVID-19. Settings and Design: Sixty (60) patients with COVID-19 detected by RT-PCR admitted in General Medicine isolation ward and COVID block of a tertiary care teaching hospital were selected by semi-purposive sampling. Materials and Methods: These patients were assessed for thyroid function tests, including total T3, free T3, total T4, free T4, TSH and anti-TPO antibody along with other baseline investigations. Patients with pre-existing thyroid–related ailments, those on levothyroxine or anti-thyroid drugs or other drugs known to interfere with the results were excluded. Results: There were 43.3% patients in mild, 26.7% in moderate, and 30% in severe category, according to local COVID-19 severity classification protocol. 35% patients had one or more abnormality in the thyroid function, low TSH being the most common (18.33%). 9.1% patients had characteristic pattern of thyroiditis. In most of the others thyroid function did not match any typical pattern. There was no significant difference in any of the parameters of the thyroid function test between mild, moderate, and severe groups. Conclusion: Thyroid function may be abnormal in all categories of patients during COVID-19 infection, even in absence of pre-existing thyroid ailments. Although low TSH is the commonest abnormality and typical pattern of thyroiditis can be seen in a subsection of patients, in majority of the patients, thyroid function abnormality does not follow any characteristic pattern and likely represents a combination of thyroiditis and sick euthyroid syndrome in different points of its spectrum. [ABSTRACT FROM AUTHOR]

Purpose: Because of the mechanical properties of aluminium (Al), an accurate prediction of its properties has been challenging. Researchers are seeking reliable models for predicting the mechanical strength of Al alloys owing to the continuous emergence of new Al alloys and their applications. There has been widespread use of empirical and statistical models for the prediction of different mechanical properties of Al and Al alloy, such as linear and nonlinear regression. Nevertheless, the development of these models requires laborious experimental work, and they may not produce accurate results depending on the relationship between the Al properties, mix of other compositions and curing conditions. Design/methodology/approach: Numerous machine learning (ML) models have been proposed as alternative approaches for predicting the strengths of Al and its alloys. The hardness of Al alloys has been predicted by implementing various ML algorithms, such as linear regression, ridge regression, lasso regression and artificial neural network (ANN). This investigation critically analysed and discussed the application and performance of models generated by linear regression, ridge regression, lasso regression and ANN algorithms using different mechanical properties as training parameters. Findings: Considering the definition of the problem, linear regression has been found to be the most suitable algorithm in predicting the hardness values of AA7XXX alloys as the model generated by it best fits the data set. Originality/value: The work presented in this paper is original and not submitted anywhere else. [ABSTRACT FROM AUTHOR]

Background: Humans are accidental hosts in the zoonotic disease Scrub typhus. The disease though widespread in our county, it remains grossly underdiagnosed because of its non-septic clinical manifestations and lack of access to specific laboratory facilities. Aims and Objectives: The objective of present study is to evaluate the clinical presentations of Scrub Typhus among the study group. Furthermore, to assess the various laboratory findings in Scrub Typhus cases among the study group is the other objective of this study. Materials and Methods: The present study is an Institution-based, observational, and cross-sectional study conducted for 18 months with the admitted patients having 14-70 years of age. Data collected regarding patients' demographic profile, symptoms, clinical findings, laboratory, and radiological findings. Data had been summarized as mean and standard deviation for numerical variables and count and percentages for categorical variables. Results: In our study, we found that most of the patients were 14-20 years old and female population was higher. It was found that 34.3% of patients had Eschar, 42.9% of patients had Rash, and 91.4% of patients had Pallor, 8.6% of patients had Ascites, 25.7% had Edema, 8.6% of patients had Jaundice, 11.4% had shock, and 57.1% had pneumonia/pneumonitis. The present study showed that 65.7% of patients had drug response (Doxycycline). Conclusion: Knowledge of geographical distribution, evidence of exposure to vector, clinical features such as fever, rash, eschar, headache, and myalgia along with high index of suspicion are crucial factors for early diagnosis and that helps in timely treatment of the cases. [ABSTRACT FROM AUTHOR]

Prediction of pulp yield of Eucalyptus globulus wood samples based on partial least squares (PLS) regression can be optimized by utilizing specific near infrared (NIR) wavelengths. A critical feature of this approach is the weighting of constraint conditions. Equal weighting balances optimization in terms of calibration and prediction; however, there is a lack of knowledge regarding prediction performance of wood property models when different weight factors are used. In this study, pulp yield models were developed using two E. globulus data sets characterized by narrow (5%) and extreme (22.6%) yield ranges and represented by untreated and second derivative NIR spectra. The global optimization solver pySOT was used to optimize the performance of a PLS regression model in terms of wavelengths selected and number of latent variables. A linear function of R-squares for calibration ( R c 2 ) and prediction ( R p 2 ) sets was utilized as the objective function with the aim of maximizing α R c 2 + 1 - α R p 2 for all values of α between 0 (maximizing R p 2 without concern for R c 2 ) and 1 (only maximizing R c 2 ). Values of α ≤ 0.8 provided good predictive performance, whereas α ≥ 0.9 tended to overfit the calibration data indicating that models are robust for values of α from 0 to 0.8. Representative wavelengths for each data set were identified and assigned to corresponding wood components through a band assignment process. Strong agreement was observed for α ≤ 0.8 ; however, for α ≥ 0.9 , identified wavelengths generally occurred in regions unrelated to vibrations arising from specific wood components. [ABSTRACT FROM AUTHOR]

Near-infrared wavelengths selected by genetic algorithm were used to optimize partial least squares (PLS) regression models for loblolly pine (Pinus taeda L.) from the southeastern United States. Wood properties examined included density (D), microfibril angle, modulus of elasticity and tracheid coarseness (C), radial diameter (R), tangential diameter (T), and wall thickness (w)—measured by SilviScan. The optimization process was run for each property with Agenda 2020 samples utilized for PLS model development and the other sets used for prediction. The number of variables (i.e. wavelengths) varied from 10 to 100 with an optimum number identified by genetic algorithm. When compared to a full data set model (based on 700 wavelengths), calibration and prediction performance of optimized PLS regression models were superior for all properties. Importantly, representative wavelengths for each property were consistently related to recognized bond vibrations observed in specific wood components demonstrating that optimization targets wavelengths directly related to changes in wood chemistry within the examined loblolly pine samples. [ABSTRACT FROM AUTHOR]

Al–Zn–Mg–Cu alloy with different crystallite size is prepared by mechanical milling and high temperature consolidation. X-ray line profile analysis and HRTEM image show high temperature consolidation results in insignificant grain coarsening. Microhardness of the alloy as a function of crystallite size shows break down of Hall–Petch relationship. [ABSTRACT FROM AUTHOR]

This paper presents a new alternative energy dissipation solution to be used with cross-laminated timber (CLT) self-centering walls. CLT is a relatively new building product in North America and could potentially be used for high-rise construction. The development of high-performance seismic design solutions is necessary to encourage innovative structures and the design of these structures to new heights. The objective of this paper is to propose a wall-to-floor connection system that is easy to install and replace (structural fuse) after the occurrence of a large damaging event. The proposed energy dissipators are fabricated following concepts used in developing steel buckling restrained steel braces (BRB), having a milled portion, which is designed to yield and is enclosed within a grouted steel pipe. The connection system is investigated experimentally through a test sequence of displacement-controlled cycles based on a modified version of the test method developed by the American Concrete Institute (ACI) to facilitate development of special precast systems (ACI T1.1-01 Acceptance Criteria for Moment Frames Based on Structural Testing). Digital Image Correlation (DIC) was used to analyze strain behavior of the milled portion, as well as track movement of the panels during quasi-static uniaxial and cyclic testing. The results show the yield behavior and energy dissipation properties of the connection system. Damage was focused primarily in the energy dissipators, with negligible deformation and damage to the CLT panels and connections. [ABSTRACT FROM AUTHOR]

The current life cycle assessment (LCA) methodology used in structural engineering does not consider hazards like fires within its scope. Various efforts have been made to identify research gaps that need to be filled in order to accomplish a Fire-LCA. This study presented research gaps from literature to experts to determine the research gap's impact, desirability, and probability of occurrence by the year 2030. The study provides insight into what researchers should prioritize to accomplish the proposed Fire-LCA methodology. In each round the experts were asked to evaluate and comment on the impact, desirability, and probability of occurrence by the year 2030 of each identified research gap. The results of the Delphi questionnaire identified high priority research gaps for the implementation of the proposed Fire-LCA methodology. The most prioritized research gap was statistical data that would describe the number and severity of fires, fire origin, and extent of fire spread in different types of building. The results of this study can guide researchers and funding agencies to prioritize research that will fill key gaps in knowledge that prevent the implementation of a Fire-LCA methodology for building structures. • Gaps in knowledge exist and prevent the implementation of a Fire-LCA methodology for buildings. • Statistical data and reporting of real building fires is needed for the implementation of a Fire-LCA methodology. • Experts across the world do not agree on research priorities to fill gaps in knowledge needed to implement a Fire-LCA. [ABSTRACT FROM AUTHOR]

Introduction: Measles is affecting millions of people in the developing countries particularly in India with significant morbidity and responsible for thousands of death in spite of having a safe, effective, and cheap vaccine. Pulmonary complications account for 90% measles-related death. The objectives of this study were to describe age distribution, clinical features, complications, and clinical outcomes of measles cases in a referral infectious disease hospital of West Bengal. Methods: We conducted a retrospective descriptive study including 584 patients and collected information from record section on demographics, clinical features, complications, and clinical outcomes using data abstraction form. Results: The mean age of 584 measles cases was 3.7 years (±1.2 years). The most common complication was pneumonia (149 cases) followed by diarrhea and encephalopathy. Very severe pneumonia occurred in 34 cases requiring intensive care out of which 13 patients died. The average duration of stay in the hospital was 5.7 days (±3.2 days). Surprisingly, 45 cases admitted to this hospital were <9 months of age with subsequent death in 5 cases. Conclusion: Substantial number of measles cases was seen in zero to <9 months of age group and fatality due to complication was more among them. [ABSTRACT FROM AUTHOR]

The development of cross-laminated timber (CLT) technology has opened up new opportunities for low-density hardwood species, which have traditionally not been rated as construction-grade materials for structural engineering applications. Several characteristics of CLT, namely thermal performance, seismic behavior, and speed of construction, have raised interest among designers. The CLT technology has recently been used for residential and nonresidential multistory buildings and it has been identified as one of the ways of achieving tall timber building construction. As CLT gains acceptance in the industry, low-density wood species, not specified in current ANSI standards, need to be investigated for potentially successful use in CLT panels. This paper presents a study that demonstrates the viability of a Forest Stewardship Council (FSC) certified sustainable plantation grown low-density species, hybrid poplar (marketed as Pacific Albus), for use in performance-rated CLT panels by following the ANSI/APA PRG-320-2012: Standard for performance-rated cross-laminated timber shear and bending test guidelines to determine the structural viability of the CLT panels. [ABSTRACT FROM AUTHOR]

Alkali treated (5 wt. % alkali was used on the total weight of the alkali solution and the treatment time was 2 h) discontinuous cellulosic fiber (jute and sisal were used as cellulosic fibers and 35 wt. % filler content was incorporated) reinforced chemically modified ZrO2 (ZrO2 was used as 10 wt. % of total filler content. In this context, it is worthwhile to mention that when both fillers were used, the fiber content was taken in the weight ratio of 1:1.) dispersed hybrid unsaturated polyester composites were fabricated by a compression molding technique. The mechanical behavior of the fabricated composites was evaluated at the sub-micron scale by nanoindentation (indentation with an applied load on the composites surface at the nano-metric range) or depth-sensing instrumented indentation technique. The significant effect of incorporation of the dispersing phases within the unsaturated polyester matrix with respect to mechanical properties at microstructural length scale was observed. A marked improvement in the nanoindentation-derived parameters viz., nanohardness, reduced modulus, elastic recovery, and indentation creep was observed which may be attributed due to the influence of fillers inclusion within the unsaturated polyester matrix. An extensive effort was laid to analyze the dynamic mechanical properties using the sinus indentation mode associated with nanoindentation measurements to further correlate the influence of fillers addition with the indentation-derived parameters. [ABSTRACT FROM AUTHOR]

Sb 2 S 3 hollow-spheres have been synthesized through a facile chemical route that exhibited high specific surface area with broadband absorption of light over the visible region after annealing. This makes it a suitable candidate for photocatalytic applications towards the degradation of dye based water pollutants. The valance band and conduction band of the synthesized semiconductor are also positioned appropriately (w.r.t NHE) to facilitate the required redox reactions with water in presence of the photogenerated excitons. Rapid and reliable photodegradation performance has been observed toward cationic, anionic and neutral aqueous dye solutions. The reliability factor was more than 90% in degradation efficiency after 50 measured cycles for all the three cases. • Facile synthesis of Sb 2 S 3 hollow-spheres with high specific surface area. • Broadband light absorption over the visible region. • Faster photodegradation efficacy (~99% within 20 min) to water pollutants. • Good reliability factor with <10% loss in degradation efficiency after 50 cycles. Sb 2 S 3 hollow-spheres in powder form were synthesized through a facile chemical route. The synthesized material was found to have notably high specific surface area. After annealing it showed broadband absorption of light within the visible region. The valance band and conduction band of the synthesized semiconductor were also positioned appropriately (w.r.t NHE) so that the required redox reactions with water in presence of the photogenerated excitons are facilitated. These factors make it a suitable candidate for photocatalytic applications towards the degradation of dye based water pollutants. The synthesized material was established through systematic structural, compositional and optical characterizations. The photocatalytic efficacy toward the degradation of cationic, anionic and neutral dyes has been studied and the best degradation efficiency of 99.72% within 20 min has been achieved at a rate of 0.2920/min, which is significantly higher than many previous reports. Reusability, one of the major factors for the practical application of a catalyst, has also been studied in detail by investigating the probable changes in structural properties as well as in performance after several cycles of photodegradation. The reliability studies yielded encouraging results even after 50th cycle of photodegradation. The effect of catalyst loading on the photodegradation efficacy has also been studied. [ABSTRACT FROM AUTHOR]

Driven timber displacement piles are being increasingly used to densify and reinforce soils against earthquake-induced ground deformations. However, the role of timber piles to reinforce the soils and redistribute cyclic stresses to timber piles has not been established, despite their excellent flexural properties. This study presents a series of dynamic 3D, linear-elastic, numerical simulations set with the unit cell framework to evaluate the role of the tapered timber pile and design variables such as pile length, spacing and relative density on the amplification and stress redistribution possible with this ground improvement technique. The simulations indicate that the depth-dependent shear strain and shear stress redistribution variously depend on the pile length, spacing, relative density, and input motion frequency. Further, the previously-accepted shear strain compatibility assumption developed for stone columns served to greatly overestimate the magnitude in cyclic shear stress reduction. Due to the tapered pile geometry and the depth-varying soil properties implemented, the accuracy of a recently proposed approach to estimate shear stress redistribution to account for column flexure was found to depend on the flexibility of the composite soil-pile system: longer, more flexible piles and lower relative density were predicted more accurately than shorter, stiffer timber piles with higher relative density. In general, the average shear strain ratio between the improved and unimproved soil is most sensitive to pile length, moderately sensitive to relative density, and least sensitive to pile spacing, and the average ratio of shear stress reduction coefficients is most sensitive to pile spacing, moderately sensitive to pile length, and is least sensitive to relative density. • Driven displacement piles serve as ground improvements through densification and reinforcement of the surrounding soil. • Dynamic 3D numerical simulations are used to explore aspects of the reinforcement effect. • Timber piles are shown to reduce the average cyclic stresses acting on saturated soils. • Due to pile flexure, timber piles do not exhibit shear strain compatibility with the surrounding soil. [ABSTRACT FROM AUTHOR]

Timber-concrete composite (TCC) floors are becoming more commonly used in mass timber construction due to their increased stiffness and strength relative to nonconcrete composite timber floors. Current building codes do not recognize the contribution of the composite action of TCC floors to their combined strength and fire performance. Extensive structural testing is required for structural engineers to design fire protection in timber buildings that use TCC floors using either alternate means and methods or structural fire engineering. This paper presents two experimental studies conducted to examine (1) properties of shear connection systems used in TCC floors through ambient temperature direct shear tests, and (2) the behavior of TCC floors through large-scale fire tests performed at the National Research Council (NRC) in Canada. The main objective of this research is to collect data on the fundamental behavior of TCC floors in a fire. The results indicate that TCC floors have improved fire performance when compared with mass timber floors. In addition, the research quantifies the force-slip behavior of the shear connectors used and benchmarks the flexural behavior of TCC floors at ambient and elevated temperatures to existing analytical models. [ABSTRACT FROM AUTHOR]

• Evaluated effects of two brown rot fungi (Gloeophyllum trabeum and Rhodonia placenta) on performance of laterally loaded connections. • T-shaped connection assemblies modelling floor-to-wall connections in buildings were inoculated with fungi for up to 40 weeks. • Evaluated capacity, stiffness, energy dissipation, and ductility of connection assemblies through quasi-static cyclic connection tests. • Load carrying capacity and energy dissipating capacity were the most adversely affected of all the parameters evaluated. The effects of brown rot decay fungi on mechanical properties of CLT connection assemblies were investigated. CLT connections evaluated were assembled with code approved angle bracket connectors and modelled as floor-to-wall systems in mass timber buildings. Physical changes, mass loss and quasi-static cyclic tests were used to assess the performance of connection assemblies up to 40 weeks after fungal inoculation. Peak load, stiffness, energy dissipation and ductility of connections were characterized based on force–displacement data generated from the destructive test of connections. Assemblies experienced up to 57 % loss in load carrying capacity and 90 % loss in energy dissipating capacity of the connections after 40 weeks of fungal exposure. Connection stiffness was only slightly impacted over this period but wetting and redrying caused significant degradation of connection ductility. [ABSTRACT FROM AUTHOR]

• Tension tests of glued-in steel rods embedded in mass-ply panels are reported. • A two-step adhesive application process for glued-in steel rods is tested. • Monotonic and cyclic testing show no significant difference in tension capacity. • Elastic stiffness does not change with embedment depth under monotonic loads. • Further testing is required for conclusions on elastic stiffness under cyclic loads. The length of mass timber wall panels is a limiting factor in designing taller buildings. Splice designs are needed to maintain panel transportability while transferring shear and moment forces from higher floors to the foundation under lateral loading. One such splice design utilizes structural adhesive to glue threaded steel rods into the ends of wall panels being connected. This paper reports tests of the tension capacity of glued-in rods embedded in Mass Ply Panels (MPP). Twenty glued-in rods were tested under monotonic and cyclic protocols. Embedment depths ranged between 304.8 mm (12 in.) and 812.8 mm (32 in.). Load and displacement were measured during tests to report values per ISO 6891 and an international code council acceptance criteria document. Elastic stiffness, peak capacity, design capacity, and a predictive capacity equation were determined. Results showed a similar stiffness for all embedment depths and a negligible difference between peak capacities from monotonic and cyclic testing. While the data reported is only directly applicable for analysis of the specific MPP and epoxy combination used in the test program, the methodology herein can be utilized for future testing of timber-adhesive glued-in rods. [ABSTRACT FROM AUTHOR]

• Cross-laminated timber requires connection development for seismic resiliency. • Slip-friction connections tested in CLT shear walls with static, cyclic loadings. • Idealized hysteretic models accurately represent CLT rocking walls. • Repeatable performance and structural protection beyond allowable loads. • CLT walls were observed to consistently return to center. Construction of tall-wood buildings is increasing in North America. Cross-laminated timber (CLT) is one of the dominant structural mass-timber products and is a high strength, lightweight, value-added, wood-composite panel suited for shear walls. The advent of tall-wood buildings necessitates further connection development for increased seismic resiliency to meet life-safety and performance-based design objectives. A novel slip-friction connection (SFC) was tested on six 1.52 m by 3.04 m CLT walls subject to static and pseudo-static cyclic loading. The SFC used Belleville springs and brass shims to provide stable slip forces and equivalent-viscous damping ratios between 0.28 and 0.63. Half of the wall tests included a short post-tensioned restoring rod with Belleville washers. Inclined self-tapping screws (STS) were used to connect the SFCs to the CLT walls, and the SFCs were designed to reliably dissipate energy while protecting the rocking walls from damage. The wall's response followed the idealized parallelogram, or flag shaped, hysteretic models observed in other slip friction systems. Results indicate repeatable performance and structural protection at least 2.5 times STS design loads. Self-centering and partially-centering wall conditions were tested by changing the SFC slip forces, while maintaining an initial 23 kN restoring force. Based on these experiments designers will be able to apply SFCs to CLT rocking walls. [ABSTRACT FROM AUTHOR]

• Twenty in-plane shear tests on CLT surface spline connections were performed. • Splines were constructed using nails and three different screw spacings. • Nail spline connections were more ductile than the screw connections. • An engineering performance model for the CLT splines is presented. Cross-laminated timber (CLT) panels have been used as structural diaphragm elements that form the primary lateral force-resisting system in mass-timber buildings. To better understand the overall performance of CLT diaphragms, an experimental program including monotonic and cyclic in-plane shear panel-to-panel spline connections tests was conducted. The spline connections were constructed using nails and screws with different spacings. Experimental results from the testing program allow for characterization of the performance of the connection systems in terms of elastic stiffness, strength, and ductility. Based on the results of this specific testing program, nailed spline connections displayed similar performance in terms of stiffness and strength and were more 58.7% more ductile than the screw connections, which is partly explained by the larger overstrength factors observed for the screw connections. A simplified performance model is presented to aid designers in determining the elastic, inelastic, and post-peak force parameters of the various spline connections tested. [ABSTRACT FROM AUTHOR]

Background: Venetoclax plus obinutuzumab has been established as a fixed-duration treatment regimen for patients with chronic lymphocytic leukaemia. We compared the long-term efficacy after treatment cessation of the combination of venetoclax plus obinutuzumab with chlorambucil plus obinutuzumab in patients with previously untreated chronic lymphocytic leukaemia.Methods: CLL14 is a multicentre, randomised, open-label, phase 3 trial done at 196 sites in 21 countries. Eligible patients were aged 18 years or older, had untreated chronic lymphocytic leukaemia, and coexisting conditions with a cumulative illness rating scale greater than 6, a creatinine clearance of 30-69 mL/min, or both. Patients were randomly assigned (1:1) via a web and voicemail system with allocation concealment and based on a computer-generated randomisation schedule with a block size of six and stratified by Binet stage and geographical region. Patients received either venetoclax plus obinutuzumab (oral venetoclax initiated on day 22 of cycle 1 [28-day cycles], with a 5-week dose ramp-up [20 mg, 50 mg, 100 mg, and 200 mg, then 400 mg daily for 1 week], thereafter continuing at 400 mg daily until completion of cycle 12; combined with intravenous obinutuzumab for six cycles starting with 100 mg on day 1 and 900 mg on day 2 [or 1000 mg on day 1], 1000 mg on days 8 and day 15 of cycle 1, and subsequently 1000 mg on day 1 of cycles 2 through 6) or chlorambucil plus obinutuzumab (oral chlorambucil at 0·5 mg/kg bodyweight on days 1 and 15 of each cycle for 12 cycles combined with the same obinutuzumab regimen). The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. Patient enrolment is complete, and the study is registered with ClinicalTrails.gov, NCT02242942.Findings: Between Aug 7, 2015, and Aug 4, 2016, 432 patients were enrolled and randomly assigned to receive either venetoclax plus obinutuzumab (n=216) or chlorambucil plus obinutuzumab (n=216). All patients had been off treatment for at least 24 months at data collection. At a median follow-up of 39·6 months (IQR 36·8-43·0), patients given venetoclax plus obinutuzumab had a significantly longer progression-free survival than did patients given chlorambucil plus obinutuzumab (HR 0·31, 95% CI 0·22-0·44; p<0·0001). Median progression-free survival was not reached (95% CI not estimable to not estimable) in the venetoclax plus obinutuzumab group vs 35·6 months (33·7-40·7) in the chlorambucil plus obinutuzumab group. The most common grade 3 or 4 adverse event in both groups was neutropenia (112 [53%] of 212 patients in the venetoclax plus obinutuzumab group versus 102 [48%] of 214 patients in the chlorambucil plus obinutuzumab group). Serious adverse events occurred in 115 (54%) of 212 patients in the venetoclax plus obinutuzumab group and 95 (44%) of 214 patients in the chlorambucil plus obinutuzumab group. Venetoclax or chlorambucil treatment-related deaths were reported in one (1%) of 212 patients in the venetoclax plus obinutuzumab group (n=1 sepsis) and two (1%) of 214 patients in the chlorambucil plus obinutuzumab group (n=1 septic shock, n=1 metastatic skin squamous carcinoma).Interpretation: 2 years after treatment cessation, venetoclax plus obinutuzumab continues to significantly improve progression-survival compared with chlorambucil plus obinutuzumab, thereby providing a limited duration treatment option for patients with previously untreated chronic lymphocytic leukaemia.Funding: F Hoffmann-La Roche and AbbVie. [ABSTRACT FROM AUTHOR]

Hydrothermally synthesized undoped and Sr-doped hydroxyapatite-dispersed polyether ether ketone composites has been fabricated by using hot isostatic pressing technique with 5, 10, 15, and 20 wt.% as the dispersoids content. The detailed structural investigation of the fabricated composites has been performed by scanning electron microscope, high-resolution transmission electron microscope, and X-ray diffraction technique that confirmed the uniform dispersion of the dispersoids with the polyether ether ketone matrix. The microindentation measurements show that the mechanical properties of the polyether ether ketone matrix improved remarkably with incorporation of the hydroxyapatite (HAp) particles. The nondestructively evaluated elastic modulus so obtained for the matrix and composites were further validated through finite element analysis. Moreover, the in vitro cytotoxic of the fabricated nanocomposites were also evaluated to assess its potential as a bioactive material. [ABSTRACT FROM AUTHOR]

Sisal fiber along with ZrO2 particles dispersed unsaturated polyester (UP) composites were fabricated by compression molding technique. The filler contents were varied from 5 to 45 wt% with a gradual increase of 10%. The structural investigation was done using Scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. Mechanical testing was performed through microhardness tester, tensile, flexural, and Izod impact test. The optimum mechanical properties were obtained at 35 wt% of filler incorporation within UP matrix followed by a slight deterioration at 45 wt%. Fractographic images of the composites display the phenomena of fiber pull‐out, debonding and breakage. The water absorption test was performed both at room temperature and boiling water temperature conditions. The thermal insulation measurement was performed by Kawabata method. POLYM. COMPOS., 40:2790–2801, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract A Zr based alloy has been developed with a β phase (BCC) dominated microstructure by adding Nb and Mo as alloying elements. Effect of Nb has been highlighted throughout the study due to its effectiveness on volume fraction of β-Zr and Mo 2 Zr as well as on transformation temperature. It has been found that increment of Nb concentration enhances the β-phase volume fraction through the reduction of α→β transformation temperature. Detail TEM analyses elucidates the above explanation. Graphical abstract Image 1 Highlights • Zr based alloy has been synthesized by high energy ball milling and annealing. • Influence of Nb on formation of β-Zr and Mo 2 Zr phases in Zr-(0–15)Nb-5Mo alloys. • Increasing Nb in the alloy has decrease the α→β transformation temperature. [ABSTRACT FROM AUTHOR]