Short Construction Research Articles

Wooden Käpylä - the birth of a garden city

ABSTRACT The Finnish Housing Reform Association was set up in 1910 to promote public housing with new social ideas in housing design. After World War I, the association took the initiative to design affordable housing for the district of Käpylä in Helsinki. Construction was postponed by the years of instability that followed the Civil War of spring 1918. In early 1920, the City of Helsinki organised the subscription of shares in the People's Housing Company Ltd. Four– or two–family houses and even dwellings consisting of a room and a kitchen were a huge improvement to rental barracks. The quality of housing further enhanced by garden plots and communal saunas. Construction of the district resulted in notable stylistic variety. The scale of the area and the new efficient timber construction system that aimed at affordability and short construction times made Wooden Käpylä exceptional. In 1960, a design competition was organised that, had it gone ahead, would have meant the destruction of the Käpylä. The competition drew sharp criticism, and in 1971 Wooden Käpylä became protected in the master plan. Today, the street plan offers surprising views and a sense of freedom relative to previous as well as concurrent enclosed blocks.

Effect of Plate Screw Configuration on Construct Stiffness and Plate Strain in a Synthetic Short Fragment Small Gap Fracture Model Stabilized with a 12-Hole 3.5-mm Locking Compression Plate.

The aim of the study was to determine the effect of a short and long working length screw configuration on construct stiffness and plate strain in a synthetic, short fragment, small gap fracture model stabilized with a 12-hole 3.5-mm locking compression plate (LCP). Six replicates of short and long working length constructs on a short fragment, small gap fracture model underwent four-point bending. Construct stiffness and plate strain were compared across working length and along the plate. With the LCP on the compression surface (compression bending), the short working length had a significantly higher construct stiffness and lower plate strain than the long working length. Conversely, with the LCP on the tension surface (tension bending), transcortical contact between 150 and 155 N induced load sharing at the fracture gap, which significantly increased construct stiffness and decreased plate strain in the long working length. At 100 N (precontact), the short working length had a significantly higher construct stiffness and lower plate strain than the long working length, comparable with our compressing bending results. In compression bending, and before transcortical contact occurred in tension bending, the short working length had a significantly higher construct stiffness and lower plate strain than the long working length. Load sharing due to transcortical contact observed in our model in tension bending will vary with fracture gap, working length, and loading condition. These results must be interpreted with caution when considering clinical relevance or potential in vivo biomechanical advantages.

A multi-scale method for the study of deep drying of ethylene with 3A zeolite

Coal-based ethanol to ethylene (ETE) is an emerging production pathway with the advantages of a short construction period, high product purity, and few by-products. N2 is commonly used in industry to regenerate zeolites during the ETE process, with the problems of excessive material consumption, energy consumption and environmental pollution. To solve this problem, this paper proposed a method of using the ethylene product as regeneration gas to regenerate the zeolite and recover the desorbed gas. In this work, we adopted a multi-scale simulation method combining microscale apparent diffusivity and macroscale mass transfer models. Reactive force field and molecular dynamics (ReaxFF-MD) were used to obtain an equation for the diffusion coefficient versus temperature. The start-up of the twin-tower temperature and pressure swing adsorption (TPSA) process was simulated using Computational Fluid Dynamics (CFD). The TPSA process achieved an outlet water content below 5 ppm, fulfilling the process specifications.

PyPLIF HIPPOS-aided Construction and Retrospective Validation of Structure-Based Virtual Screening Protocol Targeting VEGFR2

Recently, the discovery of small molecules as inhibitors for vascular endothelial growth factor receptor 2 (VEGFR2) is of timely interest, especially in the area of ocular neovascular diseases. On the other hand, PyPLIF HIPPOS in combination with machine learning techniques has been reported to increase the prediction quality of structure-based virtual screening (SBVS) protocols. The original version of PyPLIF has served in the development of an SBVS protocol that successfully identified novel chalcone derivatives and short peptides as potent inhibitors for acetylcholinesterase. In this short communication, construction and retrospective validation of an SBVS protocol employing PyPLIF HIPPOS targeting VEGFR2 are presented to make it publicly available. The retrospective validation employed 409 active compounds and 24,950 decoys from the enhanced version of the directory of useful decoys. All compounds were docked independently 3 times using AutoDock Vina followed by the identification of the protein-ligand interaction fingerprints (PLIF) employing PyPLIF HIPPOS. The derived ensemble PLIF descriptors were then used in the decision tree construction using a machine-learning technique called recursive partitioning and regression trees. The best decision was then incorporated in the SBVS protocol. The F-measure and enrichment factor values of the SBVS protocol were 0.387 and 76.879, respectively. Hence, the SBVS protocol is readily available to screen small molecules or short peptides.

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

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

Seismic performance of an innovative self-centering and repairable connection with SMA bolts in modular steel construction

Modular steel construction (MSC) is widely noticed and adopted in the building industry for its benefits of short construction period, low carbon emission, and great flexibility. The performance of inter-module connections, including the strength, toughness and ductility, is the focus of maintaining the load transfer mechanism and overall stability of modular structures. The structure with favorably designed connections can dissipate expected energy under cyclic loading with reduced structural damage. A self-centering and repairable connection (SRC) is herein proposed, with the benefits of a distinct load transmission path and easy assembly. Four full-size specimens were fabricated and tested under low-cycle loading, and the tested specimens were subsequently repaired by replacing angle cleats. The failure mode and bearing capacity of both SRC and repaired SRC specimens were investigated. Several seismic performance indices of the specimens, including hysteresis curves, strength and stiffness degradation, energy dissipation capacity, self-centering and repairable ability, were obtained. Furthermore, the performance of the SRC was comprehensively assessed according to Eurocode 3 Part 1–8, Chinese code GB 50011-2010, and American code AISC 341-16. In addition, an accurate finite element model (FEM) of the SRC was created and verified using experimental results. The developed FEM was used to investigate the effects of critical parameters, including angle cleat thickness and grade, vertical bolt diameter, and SMA bolt number and diameter, on the seismic performance of SRCs. Both experimental and FEM results show that only the replaceable angle cleats experienced the noticed plastic deformation for SRC specimens under cyclic loading, and SMA bolts provided the required self-centering force. It can be hence concluded that the proposed SRC can achieve the expected self-centering and recovery function.

Out-of-plane cross-angle bending stiffness of cross-laminated timber

The increasing use of cross-laminated timber (CLT) in construction worldwide can be attributed to its combination of sustainability, structural efficiency, biaxial strength and stiffness, short construction times, and architectural flexibility. However, when applied in free-form structures, CLT panels may exhibit irregular element geometries, resulting in deviations from their major or minor strength axes. The required out-of-plane cross-angle bending stiffness is not addressed by commonly used design methods. This study addresses this gap by examining the cross-angle bending stiffness of CLT panel segments using experimental, analytical, and numerical methods. Three different lay-ups (3-ply, 4-ply, and 5-ply) and five cross-angles (ranging from 0° to 90°) were tested under 3-point bending, demonstrating the nonlinear relation between cross-angle and out-of-plane bending stiffness. The lowest stiffness was observed for intermediate cross-angles and not when loaded along the minor strength direction. A proposed analytical model that combines the shear analogy with Hankinson's equation yielded adequate approximations. The model was verified by numerical simulations and then applied to predict the out-of-plane cross-angle bending stiffness of a wide range of CLT layups. This research provides valuable insights for working with CLT in complex geometrical designs, enhancing preliminary design.

Self-shaping free-form spatial structure with large-deformable bunched CFRP rods

Based on the bending-active concept, this paper presents a self-shaping system with bunched carbon fiber-reinforced polymer (CFRP) rods to construct complex curved surfaces, establishing an overall design and construction process. Such component consists of a bunch of slender and easily bendable CFRP rods that are preformed and then bounded by connecting joints. Then, those components form free-form spatial structures. The proposed system offers several advantages: strong designability, low transportation cost, short construction period, polished appearance and low maintenance requirements during service. For component design, to determine the shape of such component, a two-stage mechanical analysis is proposed based on the large deformation theory and finite element analysis (FEA): a form-finding process to determine the deformed component shape through its cross-sections and boundary-load conditions; and a reverse form-finding process to obtain these above-mentioned parameters from a given component shape. The reliability of both methods is verified through in-plane bending tests. A design demonstration of a saddle-shaped curved spatial structure is performed using this method. Overall, the proposed system can guide the actual construction projects of complex curved surfaces with self-shaping bunched CFRP rods.

An adaptive evolutionary strategy for long–short portfolio construction

An adaptive evolutionary strategy for long–short portfolio construction

Robust, high-yield, rapid fabrication of DNA constructs for Magnetic Tweezers

Single-molecule techniques are highly sensitive tools that can reveal reaction intermediates often obscured in experiments involving large ensembles of molecules. Therefore, they provide unprecedented information on the mechanisms that control biomolecular reactions. Currently, one of the most significant single-molecule assays is Magnetic Tweezers (MT), which probes enzymatic reactions at high spatio-temporal resolutions on tens, if not hundreds, of molecules simultaneously. For high-resolution MT experiments, a short double-stranded DNA molecule (less than 2000 base pairs) is typically attached between a micron-sized superparamagnetic bead and a surface. The fabrication of such a substrate is key for successful single-molecule assays, and several papers have discussed the possibility of improving the fabrication of short DNA constructs. However, reported yields are usually low and require additional time-consuming purification steps (e.g., gel purification). In this paper, we propose the use of a Golden Gate Assembly assay that allows for the production of DNA constructs within minutes (starting from PCR products). We discuss how relevant parameters may affect the yield and offer single-molecule experimentalists a simple yet robust approach to fabricate DNA constructs.

Torsional stability of fixation methods in basicervical femoral neck fractures: a biomechanical study

BackgroundBasicervical femoral neck fracture is a rare proximal femur fracture with a high implant failure rate. Biomechanical comparisons between cephalomedullary nails (CMNs) and dynamic hip screws (DHSs) under torsion loading are lacking. This study compared the biomechanical performance of three fixations for basicervical femoral neck fractures under torsion load during early ambulation.MethodsThe biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability.ResultsThe EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1–5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs.ConclusionsTitanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout.Graphical abstract

Parametric optimization scheme of energy dissipation and shock absorption for prefabricated concrete frame

The prefabricated concrete frame structure system has advantages such as short construction period and good seismic performance, but its deformation and energy dissipation capacity are poor under earthquake action, making it prone to damage. By improving the analysis and simulation functions of existing finite element analysis for prefabricated structures, the engineering applicability of the analysis algorithm has been improved. Then, a finite element model has been established for collaborative optimization, and a parameterized optimization scheme that meets the seismic reduction requirements has been obtained. The results show that the optimization method proposed in the study has a better effect in seeking the minimum cost, and meets the design requirements of the specification. The optimization scheme of prefabricated concrete frames designed by the research institute based on finite element analysis can efficiently optimize various parameters, greatly improving the structure energy dissipation and seismic performance.

Thermal-hydraulic characteristics analysis of unprotected accident and protection control strategy for helium-xenon cooled reactor system

The small modular helium-xenon cooled reactor has the advantages of simple and compact system structure, short construction cycle, light weight and small volume, which is very suitable for energy supply in remote area and small nuclear propulsion device. The research on accident characteristics and protection control strategies is very important to ensure the safe and reliable operation of the reactor system and mitigate the consequences of the accident. Therefore, the safety characteristics analysis program of helium-xenon cooled reactor system is developed based on Modelica language, and the transient verification of typical working conditions is carried out. The maximum relative error of the verification results was 7.91 %. Through the program, the unprotected transient conditions and corresponding protection control strategy transient conditions of external load loss accident, partial loss of heat sink accident, main valve accidental closing accident and Brayton unit efficiency step decline accident are simulated. The results show that the loss of all external loads will lead to rotation speed overspeed. The introduction of negative reactivity or bypass control can effectively control the rotation speed rise, but the introduction of negative reactivity is better than bypass control. Under unprotected control, the partial loss of the heat sink, the accidental closing of the main valve and the step down of the Brayton unit efficiency will all lead to the rapid decline of the rotation speed and mass flow rate, and there is a risk of the reactor temperature exceeding the limit. The rotation speed and mass flow rate can be effectively stabilized by load following to prevent the temperature exceeding the limit.

Study on the Principle of Cost Calculation and Economy of Steel Screw Anchors

With the popularization of mechanized construction of transmission line engineering and the improvement of environmental water protection requirements, some new foundations have been popularized, and have great advantages. The steel spiral anchor foundation has the advantages of short construction period, quick mechanization construction speed, and zero concrete and zero earthwork construction. According to the construction process and test requirements of steel screw anchor, the principle of calculating the construction and test cost of steel screw anchor is put forward, the economic critical point of steel screw anchor is obtained.

Analysis of a Prefabricated Beam Column Joint Component with Energy Consuming Steel Plates

Prefabricated structures have the advantages of short construction period, fast construction speed, and low environmental pollution. Based on this, a new type of prefabricated beam column node with energy dissipating steel plates is proposed. The structure mainly consists of prefabricated beams, columns, prefabricated energy dissipating hinge structures, etc. A finite element model is established for analysis and comparison with cast-in-place structures. It is found that the seismic performance of prefabricated beam column nodes with energy dissipating steel plates is better, and their displacement ductility and energy dissipation capacity are much higher than cast-in-place structures. A prefabricated frame structure system with energy dissipating steel plates is established to study its structural failure sequence.

Insulation performance improvement for drywall using highly insulated steel studs with slots

Drywall systems are a highly constructible technology with short construction times that allow the recycling and reuse of materials. However, steel studs used to anchor the insulation can cause thermal bridging owing to their high thermal conductivity, which can reduce the insulation performance and thermal comfort of occupants. This study proposes a new design method for drywall systems that can overcome the shortcomings and contribute to building energy conservation. Studs with slots applied in the web area are proposed, and the thermal performance and optimal slot size were determined by thermal analysis simulations. Through sensitivity and regression analysis, a design method for drywall was proposed. The developed studs showed an increase in insulation performance of approximately 22.1 % compared with conventional studs. The error rate between the simulation results and the regression model was 0.4 %. An experiment was conducted to verify the insulation performance of the studs. The results of this study can contribute to expanding the application of drywall technology in the building field by solving the problem of thermal bridging and providing a unique perspective on the drywall.

Combinatorial Nullstellensatz and Turán numbers of complete r-partite r-uniform hypergraphs

In this note we describe how Lasoń's generalization of Alon's Combinatorial Nullstellensatz gives a framework for constructing lower bounds on the Turán number ex(n,Ks1,…,sr(r)) of the complete r-partite r-uniform hypergraph Ks1,…,sr(r). To illustrate the potential of this method, we give a short and simple explicit construction for the Erdős box problem, showing that ex(n,K2,…,2(r))=Ω(nr−1/r), which asymptotically matches best known bounds when r≤4.

278 Lateral Anterior Column Release in Short Construct... Is It Worth It?

INTRODUCTION: Adjacent Segment Disease (ASD) is a common complication after lumbar spinal fusions. Ways to reduce the rates for ASD are highly sought after mainly to avoid re-operation. METHODS: We conducted a retrospective cohort study that consisted of patients that underwent 1-2 level LLIF for degenerative spine disease from 2014-2020. Patients needed to have at least one year of follow-up and have postoperative standing x-rays. Preoperative demographics, perioperative surgical characteristics, and postoperative outcomes were recorded. RESULTS: 92 patients were included for analysis after inclusion criteria. Median follow-up period of 25 months. 54% F, 64 years of age, BMI 31. 11 patients (12%) developed ASD at a median follow up of 29 months. In the patients with ASD, 9 (82%) underwent anterior column release (ACR) with the placement of hyper-lordotic cages > 20 degrees. In our cohort of short construct LLIF ACR was done 9 patients (L3/4 (7 patients) and L4/5 (2 patients). In the univariate analysis we found that age-adjusted PI-LL mismatch (p < 0.003), the use of a hyperlordotic cage (p = 0.003), and ACR release (p < 0.001) were significantly associated with ASD. A multivariate logistic regression model was created and showed only that ACR was predictive for ASD (Odds Ratio: 69.1, 95% confidence interval: 10.71-446.3, p < 0.001). CONCLUSIONS: ACR was predictive for developing ASD in lumbar degenerative disease patients that undergo short-segment LLIF. While other factors may play a role, this was the predominant factor identified in our cohort with at least 10-fold increase risk. ACR is a powerful tool to be use in only spinal deformity. We recommend against ACR in short construct LLIF.

A Comparative Biomechanical Study of Alternative Medial Collateral Ligament Reconstruction Techniques

Background: There is little evidence of the biomechanical performance of medial collateral ligament (MCL) reconstructions for restoring stability to the MCL-deficient knee regarding valgus, external rotation (ER), and anteromedial rotatory instability (AMRI). Hypothesis: A short isometric reconstruction will better restore stability than a longer superficial MCL (sMCL) reconstruction, and an additional deep MCL (dMCL) graft will better control ER and AMRI than single-strand reconstructions. Study Design: Controlled laboratory study. Methods: Nine cadaveric human knees were tested in a kinematics rig that allowed tibial loading while the knee was flexed-extended 0° to 100°. Optical markers were placed on the femur and tibia and displacements were measured using a stereo camera system. The knee was tested intact, and then after MCL (sMCL + dMCL) transection, and loaded in anterior tibial translation (ATT), ER, varus-valgus, and combined ATT + ER (AMRI loading). Five different isometric MCL reconstructions were tested: isolated long sMCL, a short construct, each with and without dMCL addition, and isolated dMCL reconstruction, using an 8 mm–wide synthetic graft. Results: MCL deficiency caused an increase in ER of 4° at 0° of flexion (P = .271) up to 14° at 100° of flexion (P = .002), and valgus laxity increased by 5° to 8° between 0° and 100° of flexion (P < .024 at 0°-90°). ATT did not increase significantly in isolated MCL deficiency (P > .999). All 5 reconstructions restored native stability across the arc of flexion apart from the isolated long sMCL, which demonstrated residual ER instability (P≤ .047 vs other reconstructions). Conclusion: All tested techniques apart from the isolated long sMCL graft are satisfactory in the context of restoring the valgus, ER, and AMRI stability to the MCL-deficient knee in a cadaveric model. Clinical Relevance: Contemporary MCL reconstruction techniques fail to control ER and therefore AMRI as they use a long sMCL graft and do not address the dMCL. This study compares 5 MCL reconstruction techniques. Both long and short isometric constructs other than the long sMCL achieved native stability in valgus and ER/AMRI. Double-strand reconstructions (sMCL + dMCL) tended to provide more stability. This study shows which reconstructions demonstrate the best biomechanical performance, informs surgical reconstruction techniques for AMRI, and questions the efficacy of current popular techniques.

THE OPPORTUNITIES AND CHALLENGES OF XI'AN CITY IMAGE BUILDING THROUGH THE GOVERNMENTAL PERSPECTIVE IN TIK-TOK PLATFORM: A SYSTEMATIC NARRATIVE REVIEW

Background: In the context of the rapidly advancing 5G era, mobile short video platforms have become integral to modern media communication. Tik-Tok, a prominent social media app in China with over a billion daily users, has transformed how people access information. This evolution has profound implications for shaping a city's image, which holds sway over a region's influence in an increasingly globalized world. Objective: This systematic narrative literature review explored empirical evidence on city image building and communication on Tik-Tok platform. And also gave a new strategy from governmental perspective for the building and dissemination of Xi'an's city image on the Tik-Tok platform in the future. Participants and setting: This research selected the article on the Scopus, and CNKI databases. The review is limited to articles published in journals in English and Chinese during the three years from January 1, 2020 to January 1, 2023. Methods: The systematic approach to literature reviewing was utilized 'Systematic Narrative Review'. This research used content analysis to systematically organize the literature over the last three years. Results: The review summarizes the findings of the selected studies, which show that governments have the ability to strategically use the Tik-Tok short-form video platform to intangibly build and communicate the urban image of a specific region in the face of the challenges of developing urban communication. Conclusion: The review highlights that short video-driven city image construction and communication pose noteworthy opportunities and challenges. This warrants deeper scholarly investigation. Through studying Xi'an's TikTok-based city image building, this paper explores governmental strategies for content creation and communication.