Drift Levels Research Articles

Seismic Performance of Steel Buildings with Eccentrically Braced Frame Systems with Different Configurations

Although eccentrically braced frames (EBFs) can be used with different configurations according to architectural requirements, it has not yet been indicated which configuration has a better seismic performance; therefore, this paper presents an analytical study focused on evaluating the seismic behavior of various steel buildings with EBF systems, factoring in different configurations. Furthermore, the objective is to compare the performances of EBF systems with one another, to learn more about their structural efficiency. The results obtained indicate that seismic response, in terms of peak interstory drifts, depends on the structural period and hysteretic behavior of the links, because high levels of plastic rotation increase lateral displacement. In addition, it was observed that maximum drift demands are concentrated in the lower floors where the links exhibit inelastic behavior, while the level of interstory drift decreases as height increases.

Genomic variation in montane bumblebees in Scandinavia: High levels of intraspecific diversity despite population vulnerability.

Populations of many bumblebee species are declining, with distributions shifting northwards to track suitable climates. Climate change is considered a major contributing factor. Arctic species are particularly vulnerable as they cannot shift further north, making assessment of their population viability important. Analysis of levels of whole-genome variation is a powerful way to analyse population declines and fragmentation. Here, we use genome sequencing to analyse genetic variation in seven species of bumblebee from the Scandinavian mountains, including two classified as vulnerable. We sequenced 333 samples from across the ranges of these species in Sweden. Estimates of effective population size (NE ) vary from ~55,000 for species with restricted high alpine distributions to 220,000 for more widespread species. Population fragmentation is generally very low or undetectable over large distances in the mountains, suggesting an absence of barriers to gene flow. The relatively high NE and low population structure indicate that none of the species are at immediate risk of negative genetic effects caused by high levels of genetic drift. However, reconstruction of historical fluctuations in NE indicates that the arctic specialist species Bombus hyperboreus has experienced population declines since the last ice age and we detected one highly inbred diploid male of this species close to the southern limit of its range, potentially indicating elevated genetic load. Although the levels of genetic variation in montane bumblebee populations are currently relatively high, their ranges are predicted to shrink drastically due to the effects of climate change and monitoring is essential to detect future population declines.

Voxel-based structural monitoring model for building structures using terrestrial laser scanning

This study presents a structural monitoring model for building structures using Terrestrial Laser Scanning (TLS). The model includes three phases for data collection, processing, and structural assessment, integrating a voxel-based data processing approach with polynomial regression to estimate structural responses. To investigate the influence of voxel size on estimating responses, several voxel structures were generated, each utilizing a uniform voxel size with voxel sizes ranging from 10 mm to 40 mm. The effectiveness of this proposed model was examined on a large-scale, two-story steel building under gravity and lateral loads. The estimated results demonstrated reasonable agreement with reference data, particularly at higher drift levels. Despite environmental challenges, such as obstacles and blind spots, the regression method effectively mitigated data gaps. This research indicates the viability of TLS as an efficient and effective contactless alternative for structural assessment in terms of speed and accuracy. Future advancements in laser scanning technology could further enhance data density and precision, thus extending the applicability of the model to larger-scale projects.

Genomic evolution of island birds from the view of the Swinhoe's pheasant (Lophura swinhoii).

Island endemic birds account for the majority of extinct vertebrates in the past few centuries. To date, the evolutionary characteristics of island endemic bird's is poorly known. In this research, we de novo assembled a high-quality chromosome-level reference genome for the Swinhoe's pheasant, which is a typical endemic island bird. Results of collinearity tests suggest rapid ancient chromosome rearrangement that may have contributed to the initial species radiation within Phasianidae, and a role for the insertions of CR1 transposable elements in rearranging chromosomes in Phasianidae. During the evolution of the Swinhoe's pheasant, natural selection positively selected genes involved in fecundity and body size functions, at both the species and population levels, which reflect genetic variation associated with island adaptation. We further tested for variation in population genomic traits between the Swinhoe's pheasant and its phylogenetically closely related mainland relative the silver pheasant, and found higher levels of genetic drift and inbreeding in the Swinhoe's pheasant genome. Divergent demographic histories of insular and mainland bird species during the last glacial period may reflect the differing impact of insular and continental climates on the evolution of species. Our research interprets the natural history and population genetic characteristics of the insular endemic bird the Swinhoe's pheasant, at a genome-wide scale, provides a broader perspective on insular speciation, and adaptive evolution and contributes to the genetic conservation of island endemic birds.

Can herbicides of different mode of action cause injury symptoms in non-herbicide-tolerant young soybean due to simulated drift?

Accidental herbicide drift onto neighboring crops, such as soybeans, can seriously harm non-target plants, affecting their growth and productivity. This study examined the impact of simulated drift from ten different herbicides (2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, hexazinone, diuron, diquat, nicosulfuron, and isoxaflutole) on young soybean plants. These herbicides were applied at three simulated drift levels (1/4, 1/16, and 1/32) equivalent to recommended commercial doses, and the resulting symptoms were carefully evaluated. Simulated drift caused distinctive symptoms, including chlorosis, twisting, necrosis, and growth abnormalities, varying depending on each herbicide’s mode of action. Dicamba proved more toxic than 2,4-D, and symptom severity increased with drift proportion, with all herbicides causing over 30% injury at the 1/16 proportion. Notably, 2,4-D, dicamba, glyphosate, hexazinone, and diquat exceeded the half-maximal inhibitory concentration (IC50) value, significantly reducing total biomass. Dicamba consistently caused 50% injury at all proportions, while hexazinone, at the highest dose proportion, led to plant mortality. Dicamba also had biomass accumulation beyond the growth reduction (GR50), whereas hexazinone exhibited less than 10% accumulation due to its capacity to induce plant mortality. This study emphasizes the importance of understanding herbicide drift effects on non-target crops for more effective and safe weed management strategies.

The genome-wide relationships of the critically endangered Quadricorna sheep in the Mediterranean region.

Livestock European diffusion followed different human migration waves from the Fertile Crescent. In sheep, at least two diffusion waves have shaped the current breeds' biodiversity generating a complex genetic pattern composed by either primitive or fine-wool selected breeds. Nowadays most of the sheep European breeds derive from the second wave which is supposed to have largely replaced oldest genetic signatures, with the exception of several primitive breeds confined on the very edge of Northern Europe. Despite this, some populations also in the Mediterranean region are characterised by the presence of phenotypic traits considered ancestral such as the policeraty, large horns in the ram, short tail, and a moulting fleece. Italy is home of a large number of local breeds, albeit some are already extinct, others are listed as critically endangered, and among these there is the Quadricorna breed which is a four-horned sheep characterised by several traits considered as ancestral. In this context we genotyped 47 individuals belonging to the Quadricorna sheep breed, a relict and endangered breed, from Central and Southern Italy. In doing so we used the Illumina OvineSNP50K array in order to explore its genetic diversity and to compare it with other 41 breeds from the Mediterranean region and Middle-East, with the specific aim to reconstruct its origin. After retaining 32,862 SNPs following data filtering, the overall genomic architecture has been explored by using genetic diversity indices, Principal Component Analysis (PCA) and admixture analysis, while the genetic relationships and migration events have been inferred using a neighbor-joining tree based on Reynolds' distances and by the maximum likelihood tree as implemented in treemix. The Quadricorna breed exhibit genetic diversity indices comparable with those of most of the other analysed breeds, however, the two populations showed opposing patterns of genetic diversity suggesting different levels of genomic inbreeding and drift (FIS and FROH). In general, all the performed genome-wide analyses returned complementary results, indicating a westward longitudinal cline compatible with human migrations from the Middle-East and several additional genetic footprints which might mirror more recent historical events. Interestingly, among the Italian breeds, the original Quadricorna (QUAD_SA) first separated showing its own ancestral component. In addition, the admixture analysis does not suggest any signal of recent gene exchange with other Italian local breeds, highlighting a rather ancestral purity of this population. On the other hand, both the neighbor-joining tree and the treemix analysis seem to suggest a proximity of the Quadricorna populations to breeds of South-Eastern Mediterranean origin. Although our results do not support a robust link between the genetics of the first wave and the presence of primitive traits, the observed genetic uniqueness together with the inferred phylogeograpic reconstruction would suggest an ancient presence of the Quadricorna breed in the Italian Peninsula. Because of this singularity, urgent conservation actions are needed in order to keep the breed and all related cultural products alive.

Detecting Item Parameter Drift in Small Sample Rasch Equating

ABSTRACT Screening items for parameter drift helps protect against serious validity threats and ensure score comparability when equating forms. Although many high-stakes credentialing examinations operate with small sample sizes, few studies have investigated methods to detect drift in small sample equating. This study demonstrates that several newly researched drift detection strategies can improve equating accuracy under certain conditions with small samples where some anchor items display item parameter drift. Results showed that the recently proposed methods mINFIT and mOUTFIT as well as the more conventional Robust-z helped mitigate the adverse effects of drifting anchor items in conditions with higher drift levels or with more than 75 examinees. In contrast, the Logit Difference approach excessively removed invariant anchor items. The discussion provides recommendations on how practitioners working with small samples can use the results to make more informed decisions regarding item parameter drift.

Finite element analysis of RC moment-resisting frames to assess effective slab width; a parametric study

In reinforced concrete (RC) moment-resisting frames (MRFs) with cast-in-situ slabs, the slab action as tension flange during lateral loading enhances the flexural capacity of beams in negative moments. This enhancement may lead to strong beam-weak column unfavorable failure mode in these structures. Field observations of RC MRFs during strong ground motion indicated that the effective slab width values considered by the seismic provisions of the design codes are not adequate to guarantee the achievement of the design method of weak beam-strong column. An accurate estimation of effective slab width needs to assess factors such as geometrical characteristics of connection, continuity of models, and imposed story drift level. A 3D spatial two-story RC MRF was developed using finite element analysis (FEA) to explore the effect of mentioned factors on effective slab width. For finite element (FE) modeling of RC MRF, the concrete damaged plasticity (CDP) model is applied. The CDP model parameters are defined using a mesh-independent methodology introduced in the literature. Comparing the FEA results and results obtained from three half-scale RC MRFs, tested under reversed cyclic loading conditions showed an excellent correlation. The results predicted by the FE model in terms of lateral load–displacement response, reinforcement yielding sequence, crack patterns, and failure modes had a considerable agreement with test observations. The validated FE model was used to develop the other models to conduct a parametric study in the next step. Geometric parameters studied in this paper through numerical modeling were longitudinal and transverse beam length and height, and cross-sectional column dimension. Results of the parametric study showed that the effect of the ratio of transverse beam length to height is significantly more than the ratio of longitudinal beam length to height. The trend of effective slab width versus story drift depends on connection geometry, especially the ratio of transverse beam length to transverse beam height. Finally, an equation was driven to predict the effective slab width using linear regression analysis.

Effect of Low Rate of Dicamba on Tomato (Solanum lycopersicum) at Different Growth Stages

Tomatoes are highly sensitive to herbicides, and concerns have been raised regarding off-target movement of dicamba and 2,4-D with the advent of new technologies in crops like soybean and cotton. Greenhouse studies were conducted over two years to assess the effect of low rates of dicamba on tomatoes at different growth stages and investigate fruit contamination. Treatments included untreated controls and dicamba applied at 1/16X, 1/32X, 1/64X, and 1/128X rates with non-ionic surfactant (NIS). Tomato plants at three growth stages (vegetative, flowering, and fruiting) were evaluated for dicamba sensitivity. Vegetative stage plants showed the highest sensitivity, while no significant differences in injury were observed between flowering and fruiting stages. Only the untreated controls produced fruit at the vegetative stage. Plants at flowering and fruiting stages successfully produced fruits. Harvested tomato fruits from each dicamba rate and the untreated control were planted, and progeny (F1) seedlings were evaluated for dicamba symptomology. No visual dicamba symptoms were observed in the tomato progeny, indicating the absence of dicamba contamination. High-performance liquid chromatography analysis confirmed no detectable levels of dicamba in the fruit samples. These findings indicate that low rates of dicamba, even at simulated drift levels, do not significantly affect tomatoes or result in fruit contamination. The results contribute to understanding the risks associated with herbicide drift and its impact on sensitive crops like tomatoes.

Seismic behavior of concentric and eccentric New-RCS through-beam joints

Composite frame structures with high-strength reinforced concrete columns (New RC) and steel beams (S) are called New RCS systems. The key to the development of the New RCS system is the development of beam-column joint details. Thus, in this study, four large-scale beam-column subassembly specimens: three interior joint specimens, and one exterior joint specimen, were designed and cyclically tested to investigate the seismic behavior of the New RCS joint. Two tested interior joint specimens had beams framing to the New RC column with eccentricities, while the other specimens had concentrically framing beams. All the specimens exhibited stable and ductile hysteretic responses. The experimental study showed that the proposed joint details could develop the desirable beam flexural yielding while limiting joint damage for drift levels up to 6%. However, at very high drift levels (≥ 6%), the overstrength of the highly compact cross-section of the steel beams of the test specimens resulted in significant joint damage for the interior joint specimens. The experimental study demonstrated that the proposed New RCS joints were able to accommodate eccentrically framing beams without hampering the seismic response.

Genomic population structure and inbreeding history of Lake Superior caribou.

Caribou (Rangifer tarandus) have experienced dramatic declines in both range and population size across Canada over the past century. Boreal caribou (R. t. caribou), 1 of the 12 Designatable Units, has lost approximately half of its historic range in the last 150 years, particularly along the southern edge of its distribution. Despite this overall northward contraction, some populations have persisted at the trailing range edge, over 150 km south of the continuous boreal caribou range in Ontario, along the coast and nearshore islands of Lake Superior. The population history of caribou along Lake Superior remains unclear. It appears that these caribou likely represent a remnant distribution at the trailing edge of the receding population of boreal caribou, but they may also exhibit local adaptation to the coastal environment. A better understanding of the population structure and history of caribou along Lake Superior is important for their conservation and management. Here, we use high-coverage whole genomes (N = 20) from boreal, eastern migratory, and barren-ground caribou sampled in Manitoba, Ontario, and Quebec to investigate population structure and inbreeding histories. We discovered that caribou from the Lake Superior range form a distinct group but also found some evidence of gene flow with the continuous boreal caribou range. Notably, caribou along Lake Superior demonstrated relatively high levels of inbreeding (measured as runs of homozygosity; ROH) and genetic drift, which may contribute to the differentiation observed between ranges. Despite inbreeding, caribou along Lake Superior retained high heterozygosity, particularly in genomic regions without ROH. These results suggest that they present distinct genomic characteristics but also some level of gene flow with the continuous range. Our study provides key insights into the genomics of the southernmost range of caribou in Ontario, beginning to unravel the evolutionary history of these small, isolated caribou populations.

Minimum longitudinal reinforcement in rectangular and flanged reinforced concrete walls

The amount of longitudinal steel in reinforced concrete walls is a key point in the damage distribution along the wall, although it is usually associated mainly with the prevention of temperature and shrinkage problems. A recent earthquake in New Zealand pointed out its relevance after the observation of a localized failure mode found in walls due to insufficient longitudinal steel reinforcement. Low amounts of longitudinal steel reinforcement prevent the correct distribution of the damage and can even lead to an early fracture of the reinforcement. The following study analyzes walls with different sections, such as T, L, and C-shaped walls, among others, subjected to pushover analysis, where the amount of longitudinal boundary reinforcement is varied, using values close to the minimum provided by ACI 318-19 code. The main parameter under analysis was the strain at the boundaries, revealing different behavior depending on the amount of boundary steel. When using steel amounts less than the minimum provided by the code, a greater growth for the tensile strain is observed, which in turn localizes the damage in a few zones along the wall height at low drift levels. This is overcome when using the recommended minimum steel amount. In addition, regarding the strength-to-cracking moment ratio (Mn/Mcr), although related to the growth of tensile strains, there is no specific value that can be recommended for all wall cross-sections.

Key Factors that Affect the Behavior of Steel Beams and Columns in Special Moment Frames

Steel Special Moment Frames (SMFs) are favored seismic force-resisting systems due to their architectural flexibility and high ductility. While shallow columns (section depth less than 356 mm) were commonly used in these systems before the Northridge earthquake, deeper columns (section depth greater than 356 mm) have become more popular in recent years to meet code-enforced story drift requirements economically. However, limited research exists on the hinging behavior of deep columns under axial compression and cyclic drift. Since deep columns exhibit larger slenderness ratios and are more susceptible to local and global buckling, understanding their behavior is crucial. This study investigates the behavior of fifteen four-story steel SMFs using finite element program simulations, focusing on four key factors affecting frame behavior: 1) Column bracing, 2) Beam bracing, 3) Column stiffening, and 4) Strong Column Weak Beam (SCWB) ratio. The influence of axial force level and column section properties is also examined. Results demonstrate that deep columns may experience local and/or global instabilities at relatively low story drift levels. Findings suggest that SMF performance can be enhanced by bracing deep columns at the top and bottom levels of beam flanges and adding stiffeners to the columns' web. Controlling column shortening by increasing the SCWB ratio is also recommended.

Analysis of Reinforced Concrete Shear Walls with Different End Configurations for Seismic Design

The Canterbury earthquake royal commission report highlighted that, despite being well-detailed, several reinforced concrete (RC) shear walls did not achieve their anticipated ductility capacities. In order to enhance the performance of such walls during future seismic events, the report recommended the use of concentrated and confined rebars at the wall toes coupled with high reinforcement ratios within the wall to initiate secondary cracks and extend the inelastic wall regions, thus minimizing the corresponding seismic demands. In this respect, the current study evaluates the seismic performance of RC walls with flanged and boundary element configurations compared with their typical rectangular counterparts, when different reinforcement ratios are incorporated. Specifically, the study presents a detailed analysis of six three-story half-scaled RC shear walls tested under quasi-static cyclic loading representing different seismic demands. The six walls were originally tested in two phases, where each phase had three different wall types (i.e., rectangular, flanged, and boundary element configurations). Walls in both phases had the same overall dimension and cross-section area; however, Phase II walls had 2.4 times the vertical reinforcement ratios used in Phase I walls. Following a summary of the experimental program and results, the current study presents the analytical results of the walls in terms of their load-strain relationships, curvature profiles, stiffness degradation trends, energy dissipation capacities, and equivalent viscous damping ratios. A comparison between the theoretical and experimental curvatures is also presented for the test walls at different drift levels. The results show that flanged and boundary element walls had low yield curvatures and high ultimate curvatures which resulted in enhancing their displacement ductility capacities. Flanged and boundary element walls also exhibited higher stiffness degradation rates when compared with their rectangular counterparts, leading to reduced seismic demands. Moreover, flanged and boundary element walls with high vertical reinforcement ratios (1.58%–1.63%) had higher energy dissipation capacities than their counterparts with low vertical reinforcement ratios (0.66%–0.69%). However, rectangular walls with low vertical reinforcement ratios (1.17%) showed higher ultimate curvature capacities than rectangular walls with high vertical reinforcement ratios (2.80%). Overall, the results demonstrate that future editions of relevant design standards (e.g., CSA A23.3 and ACI 318-19) should consider assigning different seismic design parameters (e.g., ultimate compressive strains, equivalent viscous damping ratios, and ductility-related modification factors) for RC shear walls based on their end configurations that can significantly alter the performance of such walls under seismic events.

Failure mechanisms and behaviour of adobe masonry buildings: A case study

Non-linear static analyses are amongst engineering community one of the most common analysis approaches for the seismic assessment of existing buildings, due to a good trade-off between information needed and results produced to assess structural safety. Pushover analyses, in fact, can provide hindsight onto structural behaviour well into the non-linear range, up unto conditions of collapse initiation and structural failure.Reliable information concerning the material’s mechanical behaviour – especially in the non-linear range - is, however, required – something which is challenging for earth-based materials, such as adobe masonry, due to the acknowledged variation of their mechanical properties.In this paper, a non-linear constitutive law for adobe masonry, numerically calibrated using experimental results and defined within the widely used computer program SAP2000®, a Finite Element software package commonly used by practicing engineers for building design and structural verification, is proposed. A total strain crack-based macro-modelling approach was pursued, and mechanical properties were validated through numerical modelling and comparison with values available in literature.The proposed constitutive model, whose reliability was proven by good agreement with experimental data, is then used to evaluate the expected seismic performance of a real case study given by an adobe building in central Portugal, representative of the city of Aveiro’s earthen heritage. Therefore, starting from this application, more hindsight over the structural behaviour of Portuguese adobe masonry buildings under failure conditions was provided, also showing the implemented model suitability for large scale structural analysis in the SAP2000® software. Sensitivity analyses are run in Finite Element environment and the structural behaviour considering different boundary conditions of the building, namely isolated and aggregate conditions, is assessed through a multi-criteria approach accounting for displacement and acceleration capacity, drift levels and safety against in-plane and out-of-plane failures.

Evolutionary transition-transversion bias by the example of the cytb gene of palearctic Muridae (Rodentia) and Vespertilionidae (Chiroptera)

A comparative analysis of the features of the transition-transversion bias of the nucleotide sequence of the cytb gene in microbats (Vespertilionidae, Chiroptera) and mice (Muridae, Rodentia) shows both general regularities and certain family-level features. A common feature of the two families is the fact of the sharp predominance of transitions over transversions at the early stages of the evolutionary process, followed by the equalization of the ts/tv-displace- ment at the species and genus levels of divergences, as well as the fact that the increase in the frequency of transitions in phyletic lineages is gradual, and the transition is intermittent. At the same time, the levels of spontaneous mutations and evolutionary drift, as well as the rate of ts/tv drift compensation, are specific to families. These circumstances do not make it possible to obtain comparable estimates of divergence in different phyla and cause insurmountable difficulties in creating a universal formula for molecular clocks.

Genomic analysis unveils genome degradation events and gene flux in the emergence and persistence of S. Paratyphi A lineages.

Paratyphoid fever caused by S. Paratyphi A is endemic in parts of South Asia and Southeast Asia. The proportion of enteric fever cases caused by S. Paratyphi A has substantially increased, yet only limited data is available on the population structure and genetic diversity of this serovar. We examined the phylogenetic distribution and evolutionary trajectory of S. Paratyphi A isolates collected as part of the Indian enteric fever surveillance study "Surveillance of Enteric Fever in India (SEFI)." In the study period (2017-2020), S. Paratyphi A comprised 17.6% (441/2503) of total enteric fever cases in India, with the isolates highly susceptible to all the major antibiotics used for treatment except fluoroquinolones. Phylogenetic analysis clustered the global S. Paratyphi A collection into seven lineages (A-G), and the present study isolates were distributed in lineages A, C and F. Our analysis highlights that the genome degradation events and gene acquisitions or losses are key molecular events in the evolution of new S. Paratyphi A lineages/sub-lineages. A total of 10 hypothetically disrupted coding sequences (HDCS) or pseudogenes-forming mutations possibly associated with the emergence of lineages were identified. The pan-genome analysis identified the insertion of P2/PSP3 phage and acquisition of IncX1 plasmid during the selection in 2.3.2/2.3.3 and 1.2.2 genotypes, respectively. We have identified six characteristic missense mutations associated with lipopolysaccharide (LPS) biosynthesis genes of S. Paratyphi A, however, these mutations confer only a low structural impact and possibly have minimal impact on vaccine effectiveness. Since S. Paratyphi A is human-restricted, high levels of genetic drift are not expected unless these bacteria transmit to naive hosts. However, public-health investigation and monitoring by means of genomic surveillance would be constantly needed to avoid S. Paratyphi A serovar becoming a public health threat similar to the S. Typhi of today.

Development and experimental verification for the coaxially formed self-centering buckling-restrained brace

The development for a new construction of self-centering buckling restrained braces (SCBRBs) was made by letting either an assembled steel BRB part or an integrally formed composite BRB part coaxially pass through an outer self-centering (SC) part with steel disc springs, and tests on the SCBRBs were conducted to validate the seismic performance and the configurations, mainly including the pattern of BRBs and that of pull rods in SC parts to keep the initial stiffness under two loading sides as close as possible. Tests show that, contrary to BRBs, the SCBRBs presenting flag-shape hysteretic curves have a significant reduction of residual drifts. Variation laws show that the residual drifts of the SCBRBs at horizontal drift levels of 2% are almost within 0.5% if self-centering ratios exceed 0.66. Besides, when the ratios under drift levels of 2% are close to 1.0, the residual drifts are approximately within the start displacements of the specimen with a SC part only. For the four SCBRBs adopting the same SC part within the drifts from 2% to 3.5%, approximately 56–73% axial strength and about 13–21% energy dissipation are from the SC part. Both types of BRB parts work stably. Except for tension fracture of plate braces, other members remain intact in SCBRBs, facilitating replacement of plate brace and reuse of intact SC part. Moreover, the interaction between two tubes in the SC part provides additional energy dissipation and horizontal resistance. Both tests and theoretical predictions reveal that the adjustment of pull rods in the SC part can adjust its initial stiffness in tension, and the pattern of employing two groups of six rods applying tension forces by two stages is preferred to decrease the difference between the initial stiffness in tension and that in compression.

Title: Hip and lower limbs 3D motion tracking using a double-stage data fusion algorithm for IMU/MARG-based wearables sensors

This paper presents an algorithm to estimate the relative orientation of body segments during 3D motion tracking, either as multiple individual body segments or as an articulated body chain. For this purpose, a double-stage data fusion algorithm (algorithm-based system) was implemented for inertial measurement units (IMU)/Magnetic Angular Rate and Gravity (MARG)-based wearable sensors during gait. The methodology considers two stages of complementary filters for the data fusion of the IMU/MARG sensors and a Proportional-Integral controller (PI) to incorporate the processed data. Quaternions were employed for the orientation estimation, a Direction Cosine Matrix quaternion-based (DCM) to estimate the relative orientation between the body mobile coordinate system and the inertial reference coordinate system, and Euler angles for the orientation representation. A customized Ambulatory Sensing Motion System (ASMS), consisting of seven monitoring devices was used for the evaluation. The double-stage algorithm-based system was compared with a digital motion processor (DMP) performance. Experimental results of the double-stage algorithm-based system indicated a 0.7° RMSE (M1) and 1° RMSE (M1-M7) with mean values lower than 1° concerning the DMP outcomes. Based on the Bland-Altman analysis, the level of agreement indicated that the double-stage algorithm-based system is neither underestimated nor overestimated and is suitable for the DMP outcome. No singularity conditions nor significant levels of noise or drift were observed in the conducted experiments. The results demonstrate the feasibility of using the proposed method for 3D human motion tracking of multiple body segments, individually or as an articulated body chain. Besides, it suits different IMU/MARG sensor-based wearable sensors.

Cyclic Testing of Glue-Laminated Beam-to-Column Connections

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.