Tension Field Research Articles

Beginner Teachers’ Encounters with the Reality of Education: Case of the “Teach First Lithuania!” Program

Beginning teachers are confronted with certain established norms, power relations, cultures and systems in schools and in education in general at the beginning of their careers. They are in a constant field of tension and can be much more sensitive to observing and questioning standards than those who have been operating in that system for a long time. In order to maintain a critical and change-oriented approach, it was chosen to describe the ideas of critical pedagogy and to analyze teachers’ experiences through this prism. Nine beginners in teaching from “Teach First Lithuania” were interviewed about their encounters with the reality of education and the choices that followed. The findings of the study revealed the prevailing hierarchical relationships in the school (often based on fear or tension); the prevalence of various types of falsification – when documents do not correspond to reality; orientation to the curriculum, standardized tests, and exams; the formation of academic classes and the “norm” of labeling – phenomena that form the habitus of the weaker and contribute to social reproduction in education. For all participants in the study, the relationship with the students is the most important, but teachers who are still teaching admit that results became very significant (due to pressure from parents, administration, and society). Staying in public schools is most motivated by a sense of appreciation, good relationships with colleagues, and commitment to students. Decisions to abandon teaching are most motivated by a heavy workload and lack of freedom.

Poliitilised ökoloogiad ja antropotseen urbaansuse pingeväljade maastikes

This article approaches complex relationships between disturbance-based ecologies and processes of urbanisation by focusing on urban fringes and valuation of life-forms within landscapes. The thematic discussion is inspired by changes of the Paljassaare Peninsula in Tallinn, which motivated the author to analytically assemble historical layers, ecological imaginations, and stories of planetary affects. The fieldwork related to the article’s argumentation is mainly based on the ethnographic method bringing together observations, interviews, and thematic narratives. The study indicates that disturbances and non-humans/birds become part of the landscape as intertwined materiality and perceiving-with, which involve tensions between presence and absence, and also tensions between past and future. The environment is not a passive “stage” in the process, but appears through emotional landscapes by creating relations between humans and non-humans. Transboundary flight trajectories of birds widen the perspective on earth-bound connections in urban space and make to rethink ways of co-existing. Urban landscapes linked to the sea accumulate diverse disturbances and ruptures, and their effects can be conflicting and interpretations change in time. The current study reveals tension fields and partial continuity of processes in which the Soviet-era legacy forms just one part in the complex assemblage. The border zone and the closed military-industrial complex in Tallinn coastal terrain generated conditions for disturbance-based ecologies, which have significantly influenced urban landscapes. Interim usages and valued ecologies slowed down effects of urbanisation and gave “voice” to particular characteristics of urban nature through which the Paljassaare Peninsula and migratory corridors of birds became part of a wider urban change. The desired (urban) nature appears as an expression of good and bad ecologies influenced by imaginations about landscapes and infrastructure. The evolvement of green areas and waterfront spaces in post-socialist cities is approached as part of Europeanisation, in which practices of European Union states are smoothly and uncritically adapted. The example of Paljassaare reveals entangled multi-dimensional connections between history, civil-society initiatives, and ideas of spatial planning, which were based on care and enabled the bordering of Natura 2000 bird protection area despite urbanisation pressure. Therefore, urban nature and urban landscapes as contested links between the (post)Soviet heritage and Europeanisation require in-depth analysis for revealing a more complex process than linear transformation. The following of disturbance-based ecologies and longer durations make it possible to problematise the Soviet-era homogenous legacy. Anthropocene traces, as a dominant force of humankind, have materialised in Paljassaare through industry, mining, building of a military complex and infrastructure of urbanisation, which, step-by-step, firmly linked the former islands to the city. Urban spatial futures lean on environmental legacy and simultaneously try to distance from the dark side of legacies. The paradox is that the terrains extensively disturbed by human activities can become meaningful within landscapes in problematising the forces of humankind and the position of humans in the context of the Anthropocene.

Recent activity and paleoseismicity of an intraplate extensional fault: the Calamocha fault (Jiloca graben, central Iberian Chain)

The Calamocha fault is an 18-km-long, NNW–SSE striking pure normal fault that moves down the northern sector of the Jiloca graben with respect to the Neogene infill of the Calatayud basin (central Iberian Chain). Its structure and kinematics are characterized by means of detailed geological mapping, morphotectonic analysis and data recording at the outcrop scale. The Calamocha fault represents the inversion of a previous contractional fault zone under the recent tensional stress field (WSW–ENE trending σ3 trajectories). The extensional activity started during the Late Pliocene (ca. 3.8 Ma), accumulating a maximum net slip of 190–230 m (long-term slip rate of 0.05–0.06 mm/a). The palaeoseismological study of three artificial exposures near Calamocha town evidenced recurrent slip during the Late Pleistocene, which proves its active character. Analysis of faulted clastic alluvial units, dated by means of optically stimulated luminescence (OSL), reveals at least eight slip events since 145.9 ± 9.1 ka, the last one being younger than 13.8 ± 0.9 ka. Only a few events represent visible accumulated displacement on the main synthetic rupture surfaces; this allows a rough estimate of the short-term slip rate (during the Late Pleistocene) of about 0.1 mm/a, faster than the long-term rate. The Calamocha fault could potentially produce a characteristic earthquake (in the sense of Schwartz and Coppersmith, J Geophys Res 89:5681–5698, 1984) with moment magnitude Mw ≈ 6.7 ± 0.3 (Mw ≈ 6.9 ± 0.3 in a scenario of activation of the whole Calamocha–Daroca fault zone), average coseismic displacement of 0.5–1.3 m and average recurrence period under 15 ka.

Pre-ignition phenomena in the tension field between operating agents and thermodynamic boundary conditions

Against the background of EU legislation with regard to CO2 emissions, a development trend towards higher geometric compression is emerging for gasoline engines. In principle, this leads – especially in combination with high mean pressure at low engine speed – to a higher pre-ignition tendency, well known as low speed pre-ignition (LSPI). The worldwide use of engine families with different fuel and oil quality represents an additional challenge, which has to be ensured within the scope of series development. IAV has extensive expertise and methodical approaches to minimize the risk of pre-ignition starting in the preliminary development through to series application and to avoid engine damage in the field. The definition and phenomenology of pre-ignition are presented. The presentation highlighted thermodynamic aspects as well as influences from operating agents and engine design. By using the IAV enthalpy approach, it is possible to evaluate designed engines objectively. This knowledge can also be used in the development of new engines concepts. Finally, a test method is presented which is used for the final assurance of the operational stability even in the case of stochastically occurring pre-ignition.

Governing digital circulation: the quest for data control and sovereignty in Germany

ABSTRACT How is the circulation of digital data to be governed? This question is the subject of often conflicting political rationalities. Focusing on internet and data politics in Germany, we identify fundamental problematizations in governing data circulation on the basis of a mixed-methods analysis of the public–political discussion. In doing so, we elaborate the genealogy of a tension between two political rationalities. On the one hand, there are the political rationalities of a global information society since the 1990s. These have propelled the free circulation of data across national borders and Germany’s integration into an international and competitive telecommunications and information technology market. In these rationalities, state intervention in the circulation of data is seen as a dangerous obstacle to economic competitiveness and social prosperity. On the other hand, there are the political rationalities of a digitally sovereign statehood since the early 2010s. These consider state intervention in data circulation as a guarantor of economic prosperity, democracy and the ability to govern. We argue that prominent political technologies of territorial regulation of data circulation currently discussed and experimented within Germany can be interpreted as attempts to harmonize this field of tension.

Toward a Renewed Theological Culture: Introduction

AbstractThis article introduces a series of articles analysing the current state of theology and inquiring about the possibilities of a renewed theological culture (not least within secular societies). It places theology, and more precisely, the conditions of a possible renewal thereof, in several fields of tension. Paradigmatic for secular societies is the tension between theology and the natural sciences. It is argued that theology and the natural sciences cultivate different modes of reasoning on different epistemic levels and that no competition between them has to be construed if one is not caught up in the premises of secularism. A brief summary of each of the contributions follows these initial remarks.

Numerical study of steel plate shear walls with diverse construction configurations

Extensive numerical research on steel plate shear walls (SPSWs) has been conducted for decades to facilitate their engineering applications. However, these studies usually adopted built-in constitutive models in commercial finite element (FE) packages and focused on SPSWs with a particular type of construction configuration, thus yielding unsatisfactory accuracy and inadequate validation. In addition, the effect of axial forces on the frame columns, which commonly exist in practice, has rarely been investigated. In this paper, a sophisticated constitutive model for structural steel is introduced and further improved by incorporating the Bao and Wierzbicki ductile damage criterion to consider strength degradation under large deformations. Then, 12 SPSW specimens with diverse construction configurations are simulated with the developed model to fully validate its effectiveness. Compared with built-in models in commercial FE software, the developed model is more accurate and can describe complicated deformation patterns under various circumstances, including extreme loading cases. On these bases, a thorough parametric analysis of 35 specimens – combining 5 construction configurations with 7 axial force ratios – is performed to quantitatively investigate the effect of axial forces applied on the frame columns. The results indicate that the axial forces can counteract the tensile forces from the tension fields; but meanwhile can also aggravate the compressive burden of the compression-side column, which induces column yielding or buckling. When the axial force ratio increases, the adverse effect gradually prevails over the beneficial effect and notably decreases the loading capacities. Accordingly, a limit axial force ratio of 0.5 and a simple linear reduction factor when calculating the ultimate loading capacity under axial forces are suggested in engineering design.

Racism in German medical education – Perspectives of racialized physicians and medical students

Abstract Background The impact of racism on health and the quality of health care services for racialized patients have been the object of prior research. The experiences of racialized medical students and physicians, who operate in a field of tension between natural sciences and practical application and between a ‘medical habitus’ and exclusionary discrimination, have hardly been examined to date. The education of (future) physicians is an especially fruitful research area in the context of the study of institutional racism in the health care system, as informal everyday experiences come together with formal knowledge and normative learning. Methods Based on expert consultations and preliminary interviews with civic stakeholders, teaching and learning materials in German medical studies were randomly sampled and used as a starting point for qualitative guided interviews with physicians and medical students in Germany who are themselves affected by racism. The first steps of the thematic analysis of these interviews are reflected upon and further developed in focus group discussions with the interviewees. Results The study is particularly concerned with the question of how certain dimensions of racism in the health care sector are related, and how racist normativity appears in this context. This is concretized in the relationship between formal and informal medical curricula as well as in the interweaving of everyday experiences and teaching materials. Conclusions There are different dimensions of relation between a hegemonic normativity in the medical curriculum and the everyday experiences of racialized medical students and physicians in Germany. Politics, faculties, publishers, and civic society may be the target of several recommendations for action regarding those diverse dimensions, e.g. the line between omission and stereotyping of several patient groups. Key messages • Hegemonic normativity in German medical education is an important and challenging issue. There are several institutional levels of medical knowledge reproducing racism in the health care sector. • Both racialized physicians and racialized patients are affected by symbolic and material forms of racism in the German health care system, which are interweaving and crucial on diverse levels.

Restoring force model of end-plate bolted shear links in eccentrically braced frames

The eccentrically braced frame with end-plate bolted shear links provides both the necessary seismic performance and a cost-effective post-earthquake repair system. In this paper a more accurate and sophisticated restoring force model was developed to describe the mechanical properties and hysteresis behavior of widely stiffened I-shape shear links with bolted end-plate connections. Cyclic loading tests were performed on 18 link specimens to investigate the post-buckling behavior and ultimate capacity of this type of members. The key observations concerning the characteristic diagonal shear buckling of the web and the development of plastic hinges in the flanges exhibited by the web panel at failure were discussed, and the key factors affecting the mechanical properties of shear links were also investigated. Further, the forms of tension field distribution and failure modes for framing web panels of the specimens with different stiffener layouts were determined. The Cardiff's tension field method was employed to predict the post-buckling strength and collapse loads of link models, and the regression analysis integrating link major configurations was used to give the stiffness expressions of multi-linear model. The hysteresis curve parameters were calibrated based on the experimental results and given by simple expressions. The comparison between numerical and laboratory results shows an accurate evaluation of the response of the widely stiffened I-shape shear links. Finally, the applicability of the proposed model is shown by means of comparing with other link models often used in eccentrically braced frames.

Combined Tension-Shear Failure of Ductile Materials

Failure of ductile materials is usually expressed in terms of effective plastic strain. Ductile materials can fail by two different failure modes, shear failure and tensile failure. Under dynamic loading, shear failure has to do with shear localization and formation of adiabatic shear bands. In these bands plastic strain rate is very high, dissipative heating is extensive, and shear strength is lost. Shear localization starts at a certain value of effective plastic strain, when thermal softening overcomes strain hardening. Shear failure is therefore represented in terms of effective plastic strain. On the other hand, tensile failure comes about by void growth under tension. For voids in a tension field there is a threshold state of the remote field for which voids grow spontaneously (cavitation) and the material there fails. Cavitation depends on the remote field stress components and on the flow stress. In this way failure in tension is related to shear strength and to failure in shear. Here, we first evaluate the cavitation threshold for different remote field situations, using 2D numerical simulations with a hydrocode. We then use the results to compute examples of rate dependent tension-shear failure of a ductile material.

Methods and Equipment for Experimental Evaluation of the Performance of Shell and Hull Structures

Introduction. Pressure-operated thick-walled hull structures are the most common type of high-duty welded structures. When these structures are loaded with internal pressure, a complex biaxial stress field arises in them, which is summed up with the fields of residual welding stresses. Therefore, when selecting a technology for manufacturing critical welded structures, the results obtained during conventional uniaxial tests of samples are insufficient. The variety of factors affecting the performance of structures, and the difficulties of separate assessment of their influence, caused the need to maximize the approximation of experimental conditions to the real working conditions of the structure.Materials and Methods. Testing of full-scale structures has a number of advantages, but they are extremely expensive, and, as a rule, only one, the weakest link, is identified, the bearing capacity of the other structural elements remains unclear. For testing, UDI radiometric installations designed for different sample sizes were used. The presented installations allow testing samples of various shapes, types of welded joints (butt, T-bar), changing the position of welded parts.Results. Without rejecting the results obtained during the testing of full-scale structures in the works of the Bauman Moscow State Technical University, DSTU, NRC «Kurchatov Institute» – CRISM «Prometey», and the authors proposed to conduct the basic scope of the research on individual structural elements that would reflect the characteristic features of loading, manufacturing technology, and operating conditions. The design of the «fitting-sheet» connections was applied, which made it possible to increase the indicators of the failure initiation and propagation to the level of the base metal.Discussion and Conclusions. Schemes of structures for obtaining a biaxial tension or bending field in samples were presented. Samples tested according to the proposed schemes allowed us to draw conclusions about the performance of welded joints under conditions close to the actual operation of the structures under study. The proposed test scheme is used by research laboratories in our country and around the world.

Experimental study and numerical simulation on the seismic behavior of diagonally stiffened stainless steel plate shear walls under low cyclic loading

To expand the application scope of stainless steel, especially in the seismic resistance, a series of systematic studies from material to members were carried out. A mechanical property test of S30408 austenitic stainless steel under monotonic loading and cyclic loading was conducted first. Then, a low cyclic loading test of 8 diagonally stiffened steel plate shear walls (SPSWs), including 6 stainless SPSWs, 1 LY100 low-yield-strength SPSW and 1 Q235 SPSW, was carried out. The failure modes, hysteresis curves, skeleton curves, ductility coefficient and equivalent viscous damping ratio-displacement angle curves of different SPSWs were compared. The mechanical behavior, energy dissipation and failure mechanism were revealed. The test results showed that the ductility of stainless SPSWs was the greatest. An effective tension field was formed after buckling. Even if the displacement angle exceeded 1/50, a good bearing capacity was displayed. A corner tearing for the LY100 and Q235 SPSWs occurred in the late stage of loading, resulting in a failure to form a reliable tension field. A notable decline in bearing capacity occurred, and the ductility was poor. The energy dissipation of the stainless SPSWs was better than that of the Q235 SPSW but slightly worse than that of the LY100 SPSW. Considering the limitation of the test, such as the limitation of the specimen number and the range of the investigation parameters, a refined finite element model was established and a parametric analysis was conducted, mainly considering the influence of aspect ratio α, height-thickness ratio λ, stiffness ratio of periphery stiffener ηf and stiffness ratio of diagonal stiffener ηs on the hysteretic performance. The research carried out herein offers a reliable reference for this new lateral force resisting structure and provides data for subsequent research, which is helpful to promote the application of stainless SPSWs in building structures.

한(恨)과 모노노아와레의 비교연구 - 종교미학적 ‘반대의 일치’ -

Han and Monono-aware have things in common, in that both the two are respectively related to the essential identity of Korea and Japan. In addition, this essay pays attention to the concepts such as “religioaesthetics” and “coincidentia oppositorum”. Religio- aesthetics means an aesthetic sense getting along with religious ethos. For example, Han might be considered as a kind of sadness which comes from the background of Korean shamanistic or Confucian culture, while Monono-aware is the one which has something to do with Japanese Shinto or Buddhism. They especially show “coincidentia oppositorum”, a situation in which the existence or identity of a thing depends upon the co-existence of at least two conditions which are opposites to each other, yet dependent on each other and presupposing each other within a field of tension. The main purpose of this essay is to comparatively investigate both commonalities and differences of Han and Monono-aware from the point of “religio-aesthetics” and “coincidentia oppositorum”. In so doing, I would like to shed light on the paradoxical relationship between Korean and Japanese culture, referring to the views of nature in two countries.

Analysis and stiffeners' design of a steel bridge girder

Plate girders are designed to carry massive loads over large spans. Flanges resist moment and web resists shear forces. Shear strength of steel girders having slender webs is much less than the yielding shear capacity. It is mainly due to the buckling of the web prior to reaching the yield strength of the material. Webs are generally reinforced with transverse stiffeners to increase their buckling strength. Stiffened webs resist shear also after buckling, which is called as post buckling strength. Tension field theories explain the formation of the post buckling strength and predict the stiffened web’s ultimate shear strength. Most design code provisions are set on tension field theories. There exists plenty of tension field theories proposed until today. This paper covers the design shear strength check and design flexural strength check and the stiffeners’ design of a steel girder specimen which was designed intentionally to fail in shear buckling. Analysis and stiffeners’ design were performed according to the provisions for load and resistance factor design (LRFD) in the ANSI/American Institute of Steel Construction (AISC) 360-16 - Specification for Structural Steel Buildings.

Goal-Setting in clinical practice: a study of health-care professionals’ perspectives in outpatient multidisciplinary rehabilitation of patients with spinal cord injury

Purpose Spinal cord injury is a complex condition requiring long-term rehabilitation. Goal-setting is considered an essential part of rehabilitation, however, knowledge of how goal-setting is practised across health-care professions, settings and diagnoses are scarce. The purpose of the study was therefore to explore health-care professionals’ perspectives on goal-setting practice in outpatient multidisciplinary rehabilitation targeting patients with spinal cord injury. Materials and methods An anthropological study combining participant-observation and focus group interviews. Data were analysed using reflexive thematic analysis. COREQ checklist was used to report the study quality. Results Health-care professionals experienced a field of tension between internationally recommended goal-setting criteria, requiring goals to be specific, measurable, realistic and time-based, and a practice influenced by patients presenting complex needs. The challenges were managed using a negotiation strategy characterized by a tinkering approach to adjust notions of measurability, realism and time frame into practice. Also, health-care professionals were challenged in relation to practising a person-centred rehabilitation approach. Conclusions We suggest rethinking the goal-setting process by allowing recommended goal-setting criteria to be adapted to a specific practice context while acknowledging goal-setting practice in its variety and flexibility as a strength. Furthermore, improved incorporation of patients’ perspectives in the practice is needed. Implications for rehabilitation To strengthen person-centred rehabilitation practice, clinicians should actively search for and engage patient-identified needs and preferences in shared goal-setting. Standard criteria of goal-setting should comply with the individual and specific participation in the everyday life of patients with SCI. SMART goals are not always the right way to formulate rehabilitation goals. A flexible and pragmatic approach is needed to reach a balance between the patients’ complex needs and the recommendations for goals to be specific, measurable, realistic, and time-based.

Intravenous administration of xenin-25 accelerates cyclic ruminal contractions in healthy conscious sheep

The present study aimed to determine the effect and mode of action of the intravenous injection of xenin-25 on cyclic contractions of the rumen in healthy conscious sheep and mode of its action. Clinically healthy male sheep were equipped with a rumen cannula by surgery under anesthesia, and ruminal contractions were recorded with manometry in conscious animals after the recovery period. Intravenous xenin-25 injection induced a cluster of premature ruminal phasic contractions in a dose-dependent manner between 0.03 and 1 nmol/kg, and the change at the highest dose was statistically significant. In contrast, intravenous neurotensin injection inhibited the amplitude of cyclic rumen contractions. The xenin-25 effect was not significantly altered by prior injection of the neurotensin receptor subtype-1 antagonist SR 48692 at 30 and 100 nmol/kg. After euthanasia the ruminal muscles were excised for in vitro experiments. A single xenin-25 application (0.3–10 μM) to the longitudinal and circular muscle strips of the rumen did not induce any change in tension or electric field stimulation-induced phasic contractions of the muscle strips. These results demonstrated that circulating xenin-25 stimulates rumen contractions by acting on sites except the intramural intrinsic nerve plexus or smooth muscles of the rumen, implying that xenin-25 acts on the gastric center and/or cholinergic efferent nerve innervated to the ovine rumen.

Den pædagogiske dobbeltbevægelse

There is currently a great deal of attention paid to the primary school as an institution that not only has to educate, but also supports the formation of the students and therefore has a dual purpose. The research and discussions in this area most often take place on a theoretical and overall level, which can create a barren distance from the specific pedagogical practice in the schools. The article bridges this gap by presenting analyzes of how teachers in primary and lower secondary school experience the field of tension between education and formation in their own teaching. The analyzes indicate that teachers experience their practice as a constant shift between two basic elements. On the one hand, they must plan, manage, frame, communicate and thus objectify the students and on the other hand, they must withdraw, suspend their control and provide space for the student to occupy a subject position in the teaching. And here this act of withdrawal in particular is highlighted as a very important, but also fragile moment that is easily overlooked. On the basis of the analyzes, the concept of The pedagogical double movement is developed. It is defined as the constant interaction between the teacher's objectifying and subjectivating actions in order to support that the student both learns what the teacher has intended, and at the same time develops his subjectivity and self determination. Thus, the concept makes an empirical contribution to research on how to understand and ‘do’ pedagogical practice that both educates and supports formation.

Behaviour of Plate Girders with Intermediate Transverse Stiffeners – Experimental Investigation

AbstractTransverse stiffeners are used in slender steel plate girders along the span to give web lateral support and increase plate girder shear resistance. According to several studies, transverse stiffeners are primarily engaged in out‐of‐plane bending to laterally limit the edges of the panel as it buckles, rather than axial compression to anchor the tension field. As a result, the axial loading defined in EN 1993‐1‐5 [1] for the design of transverse stiffeners, based on tension field action, is usually deemed to be substantially larger than that observed in laboratory testing and numerical simulations. The test results of six plate girders loaded to failure, with slender webs and two transverse stiffener geometries, are presented. FE‐models that accurately replicate the tests provide a thorough view of the plate girder behaviour. The stiffeners internal forces are evaluated during plate girder loading up to failure. The transverse stiffener internal forces attained by both models are compared. It is confirmed that both the axial compression and the bending moment in the intermediate transverse stiffeners are much lower than the values prescribed by the EN 1993‐1‐5 [1].

New Formulations for Prediction of Buckling Loads in Steel Plate Girders Through Linear and Nonlinear Stability Analysis

Buckling analysis of steel structures can be performed using either linear (LBA) or nonlinear buckling analysis (NLBA). Each method is only effective in particular conditions and improper use might lead to inaccurate predictions. Despite the extensive use of these two methods, there is a lack of research on the accuracy of each method and their limitations regarding the range of application. In this paper, these two methods are evaluated and compared for steel plate girders with a wide range of geometry and the limitations of each method are presented. The numerical modeling of steel plate girders is developed using Abaqus software. The numerical models are verified with the existing experimental results in the literature. An extensive parametric study is conducted using 123 models to investigate the effect of web height, web thickness and beam length on the results. The buckling loads predicted from the numerical models using different analysis methods are compared with those determined based on the AISC 360-16 and EN 1993-1-5 formulations and recommendations are made. Results indicate that while the nonlinear buckling analysis provides accurate predictions of buckling load and mode shape of steel beams, the linear buckling analysis is accurate only for the case of elastic buckling mode without tension field action. A new formulation is proposed to modify the LBA results in order to obtain the advantages of both analysis methods. In addition, based on the NLBA results, a much simple yet accurate equation is proposed to predict the buckling load using plate geometry and material properties instead of the complicated code equations. The accuracy of the proposed equation in comparison with the code equations is also demonstrated for 500 plate girders selected with random geometry.

Shear behavior of stainless-steel plate connectors for insulated precast concrete sandwich panels

In this study, 24 double-shear tests were performed on precast concrete insulated sandwich panels using stainless-steel plate connectors. Parameters in the test program included connector shear directions (in-plane/out-of-plane), presence of insulation (with/without), cavity widths (30 mm/80 mm/120 mm) and connector heights (120 mm/160 mm). In order to test the pure shear capacity of connectors, the insulation was removed in the in-plane shear tests. The test results indicated that the connectors with 80 mm and 120 mm cavity width failed by shear buckling and the connectors with a cavity width of 30 mm were pulled out after buckling when subjected to in-plane shear. For the out-of-plane shear tests, bending of connectors occurred in the specimens without insulation, and connectors were pulled out in the specimens with insulation. For in-plane shear connectors with cavity widths of 30 mm, 80 mm and 120 mm, the shear capacities of 120 mm high connectors were 31.8 kN, 25.8 kN and 11.5 kN respectively, while the shear capacities of connectors with a height of 160 mm were 49.3 kN, 30.2 kN and 17.6 kN. The shear capacities of the out-of-plane connectors was only 3.7% of the in-plane connectors. It was also indicated that the presence of insulation significantly contributed to shear transfer in out-of-plane shear tests, leading to 28.6 times higher shear capacity than the specimens without insulation. Based on Basler's tension field theory, an analytical model was developed to predict the shear capacity of plate connectors. Compared with test results in this paper and other studies, the predictions were in good agreement.