bluuebunny/crossref_metadata_2025 huggingface dataset:
CONSTITUTIVE MODELS FOR PREDICTING MECHANICAL PROPERTIES OF NATURAL POZZOLAN-BASED ALKALI ACTIVATED CONCRETE
Authors: Ibrahim Mohammed , Megat Johari Megat Azmi , Rahman Muhammed Kalimur , Maslehuddin Mohammed , Dafalla Mohamed Hatim
Published: February 2025

A large variety of mix design variables and environmental conditions in which alkali activated concretes (AAC) are cured, influences the nature and intensity of the binder formed. Equations developed for OPC-based concrete in various codes and published work may not accurately predict engineering properties of these AAC. AAC in this study was synthesized utilizing natural pozzolan (NP) in the presence of alkaline activators. Nano-SiO2 was added for enhancing the strength development at room temperature curing as NP is a low calcium precursor material. Development of compressive strength, flexural strength and modulus of elasticity were investigated. Using the data generated, two constitutive models, relating the compressive strength to flexural strength and modulus of elasticity were developed and compared with the equations specified in international codes for OPC-based concrete and previous studies in the area. The results show that the ACI 318, underestimates the flexural strength and overestimates the modulus of elasticity of alkali activated concrete. However, constitutive models developed in this study are in good agreement with the equations proposed in the previous works for AAC. Only the limited data available to date on the engineering properties of AAC cannot be used to establish robust constitutive relationships and more research is required in this area.
PRIORITIZATION OF PIPELINE REPLACEMENT BASED ON FAILURE RATE
Authors: Singh Amarjit , Song Xi
Published: February 2025

The purpose of this paper is to prioritize water pipelines for replacement through the analysis of pipeline failure rates and reliability. By using actual pipe condition record data from Honolulu Board of Water Supply (BWS), the constant failure rate is recognized through Bathtub profile and used to calculate reliability. This paper provides the utility manager a quantitative method to evaluate and arrange pipeline renewal. It assists in determining maintenance schedules depending on the age and type of the pipe by plotting the corresponding failure rate against time. Reliability helps determine whether a certain group of pipes are within the acceptable practice threshold to signal replacement. In this paper, the analysis of four major types of pipe systems from BWS are conducted. With the data from fiscal year (FY) 2008, the failure rates are calculated, and the reliability of all pipelines are seen to be above 80%.
MODEL ANALYSIS OF HIGH-RISE STRUCTURES FOR WIND AND EARTHQUAKE FORCES
Authors: Bhikshma Vankudothu , Hamraj Mohammed , Tejaswini Ruttal
Published: February 2025

The objective of the present work is to study and analyze the effect of wind and earthquake loads on a chosen symmetrical plan of a multi-storied building to assess the behavior of the structure in all the seismic zones based on IS 1893 and subjected to different wind velocities based on IS 875 codes. For the present study, six cases (6 floors, 9 floors and 12 floors each for earthquake and wind) are considered under which 30 structures are modelled in ETABSv16.0 software and static analysis is carried out. Structural parameters like story drifts, story displacements and story shears are studied. Finally, it is found that story drifts are found to be maximum at 2nd floor (i.e., at 6 m) and 40% increase is observed in parameters when wind speed is increased from 33 to 39 m/s and by 21% when wind speed is increased from 50 to 55 m/s. With increase in wind speed on moving to higher seismic zones, with increase in number of stories from 6 to 9 story drifts increased by 109%, story displacements increased by 185% and increased by 15% and 62% on moving to higher seismic zones. Also, wind forces on the structure subjected to variation in increasing wind speeds and increasing heights in zone II and zone III but in no case are they greater than the earthquake forces in zone IV and V.
A STUDY OF HUMAN GAIT FOR VIBRATION SERVICEABILITY EVALUATION
Authors: Setareh Mehdi , Tiller Matt
Published: February 2025

The vibration serviceability problem of structures such as building floors, footbridges, large balconies, and monumental stairs due to human movements has become an important issue, which requires careful attention of designers and engineers. Design engineers often create Finite Elements models of structures to predict their dynamic properties and their responses due to human movements. Therefore, one important aspect of the dynamic analysis of structures is the identification and quantification of excitation forces due to human movements. As part of this research study, measurements of ground reaction forces (GRF) from a number of individuals were conducted at the Virginia Tech Vibration Testing Laboratory using an instrumented force platform. The subjects walked at various speeds synchronized using a metronome. The same tests were subsequently repeated while the subjects ascended and descended over an instrumented mock stair. Considering the periodicity of human excitation force, the Fourier Series parameters (Fourier Coefficients and corresponding phase angles) of the measured forcing functions were computed. Correlations between the measured GRF's on a flat surface and an inclined surface (stair) were established. The results of the analysis were compared to the available information in the literature in an attempt to check their accuracy.
STUDY OF A MULTIPLE-TUNED MASS DAMPER FOR EXCESSIVE FLOOR VIBRATIONS MITIGATION
Authors: Setareh Mehdi , Renard Stephanie
Published: February 2025

Excessive vibration of architectural structures due to human movements has become an important serviceability issue. Tuned Mass Dampers or Vibration Absorbers have been used to mitigate the problem. This paper presents studies on an easy to fabricate, assemble and tune Multiple Tuned Mass Damper (MTMD) that can alleviate vibrations due to the excitations of several modes of a floor system. Using a test floor at the Virginia Tech Vibration Testing Laboratory, a number of experiments were conducted with the MTMD active and inactive. Different excitations generated by an electrodynamic shaker, and people walking on the floor were used. The vibration tests were repeated at various times to check the consistency of the MTMD performance. The measured reduction in floor vibrations were compared to those predicted based on the analytical equations. The results have shown that the device is effective in reducing floor vibrations due to human movements in spite of its small mass compared to the mass of the test floor.
INFLUENCE OF RAILING STIFFNESS ON WHEEL LOAD DISTRIBUTION IN TWO-SPAN CONCRETE SLAB BRIDGES
Authors: Jaber Sarah , Mabsout Mounir , Tarhini Kassim
Published: February 2025

The American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications or LRFD do not account for the presence of railings in the analysis and design of concrete slab bridges. This paper presents a parametric investigation of the influence of railing stiffness on the wheel load distribution in simply-supported, two-equal-span, and one-and two-lane reinforced concrete slab bridges using the finite-element analysis (FEA). A total of 160 bridge cases were modeled and bridge parameters such as span lengths and slab widths were varied within practical ranges. Various railing stiffness were investigated by assuming railings built integrally with the bridge deck and placed on both edges of the bridge. The FEA wheel load distribution and longitudinal bending moments were compared with reference bridge slabs without railings as well as to the AASHTO design procedures. Accordingly, the presence of railings reduced the FEA negative moments by a range of 54% to 72% and the FEA positive moments by a range of 40% to 61% depending on the railing stiffness. This reduction in slab moments due to the presence of railings could be considered an increase in the bridges load carrying capacity. The results of this investigation will assist bridge engineers in better designing and/or evaluating concrete slab bridges in the presence of railings. This could also be considered an alternative for strengthening existing concrete slab bridges.
PERIODIC BOLT PLACEMENT IN STEEL STRUCTURES FOR GUIDED DAMAGE DETECTION
Authors: Zhang Lu , Ozevin Didem , Okudan Gorkem
Published: February 2025

Connections form the weakest link in structural systems. Bolted connections are especially susceptible to stress corrosion cracking due to stress-riser points at the bolt edges and the intrusion of water between plates leading to galvanic corrosion. Bolts are conventionally placed based on minimum and maximum spacing requirements guided by American Institute of Steel Construction. Unfortunately, the detectability of crack and corrosion is currently not a design variable. In this study, bolts are placed in periodic pattern such that they exhibit unique frequency response. The periodic placement allows modeling only unit cell in the shape of hexagon with periodic boundary conditions to obtain the frequency response. When damage occurs, the periodic pattern is broken, and the frequency response behavior changes. The influence of crack to vibration modes is numerically modeled, and the damage detection ability with unique bolt placement is demonstrated. It is shown that the spatial distribution of bolt can assist the damage detection ability, which should be considered as a criterion in the design of bolted connections.
THIN-WALLED STEEL TUBULAR COLUMNS WITH UNIFORM AND GRADED THICKNESS UNDER CYCLIC LOADING
Authors: Al-Kaseasebh Qusay , Mamaghani Iraj H.P
Published: February 2025

Thin-walled steel tubular circular columns are widely used as cantilever bridge piers due to their geometric efficiency, aesthetic appearance, and high earthquake resistance. However, local buckling, global buckling, or interaction between both is usually the main reason of significant strength and ductility loss in these columns, which eventually leads to their collapse. This paper investigates the behavior of uniform circular (C) and graded-thickness circular (GC) thin-walled steel tubular columns under constant axial and cyclic lateral loading. The GC column with size and volume of material equivalent to the C column is introduced and analyzed under constant axial and cyclic lateral loading. The analysis carried out using a finite-element model (FEM), which considers both material and geometric nonlinearities. The accuracy of the employed FEM is validated based on the experimental results available in the literature. The results revealed that, significant improvements in strength, ductility, and post-buckling behavior of thin-walled steel columns obtained using the GC column.
STRENGTHENING METHOD OF UNREINFORCED MASONRY WALLS BY BRACE ELEMENTS
Authors: Ganbaatar Ariunaa , Yamamoto Haruyuki
Published: February 2025

The ductility and strength properties of lightweight steel brace element for structural strengthening of unreinforced masonry (URM) wall is reported in this study. The performance of URM wall without brace and with brace is evaluated by an elastoplastic nonlinear analysis including the yield criterion, flow rule and hardening rule. Masonry constituent is implemented into two-dimensional finite element model developed in Fortran code. The brittle failure of URM wall is analyzed using by an interface element to model bricks and joints. Two types of steel brace elements which can resist only tension and both tension and compression have been considered to increase the ductility of URM wall. The comparison between experimental and numerical results adopted in simplified-micro masonry modeling is illustrated with the relationship between force and displacement. The ductility and strength of masonry wall with the tension and the tension-compression brace element were different results of URM wall by in-plane pushover analysis. As for the simplification for a calculation of masonry wall, equivalent masonry model is discussed and besides diagonal brace elements, the additional vertical brace element is assumed for the high masonry wall by the numerical analysis.
ACCURATE MODELING OF CURVED STEEL I-GIRDER BRIDGE
Authors: Zhu Yifan , Xu Chaoran , Fu Chung C.
Published: February 2025

A curved and/or skewed steel I-girder bridge, in addition to the basic vertical shear and bending effects, will be subjected to torsional and warping effects. Thus, simplified hand calculation and line girder methods, might not be enough when bridges are to be analyzed. Refined methods, termed by AASHTO, have to be adopted. This paper has investigated the closeness and difference between curved bridge finite element models using 2-D gird and 3-D shell elements of I-girders, both are part of AASHTO refined method. Moreover, the results are calibrated by comparing analysis result with various two-dimensional and three-dimensional computations with varied curvature effects. It is concluded that when introducing torsional effects to finite element models, the modified torsional constant J with consideration of warping effect should be taken into the 2-D grid model as a refined model. When using 3-D shell elements as the refined model, stiffeners and connection plates play an important role of global model stiffness and should not be ignored, especially for sharp curved steel I-girder bridges.
COMPARATIVE STUDY ON THE BENDING PROPERTIES FOR TWO TYPES OF COMPOSITE BEAMS
Authors: Liang Xian , Duan Shujin , Niu Runming , Li Fang
Published: February 2025

The difference between the steel and concrete composite-laminated action beam and the double steel and concrete composite action beam is in the connection of the top concrete slab and the steel top flange. The bending properties about the composite-laminated beam and the double composite beam in the negative flexural region are investigated in this paper. The relation of the cross section bending moment-curvature for the two types of composite beams under the action of negative bending moment are drawn by the whole process analysis method, and then the corresponding cracking moment, elastic ultimate bending moment and plastic ultimate bending moment are obtained. The analysis results have a good agreement with test data. Although the sectional bending stiffness and bending-carrying capacity of the composite-laminated beam and the double composite beam are comparable in the elastic state, the crack resistance of the composite-laminated beam is much better than that of the double composite beam.
EXPERIMENTAL STUDY ON CONTINUOUS BEAM TYPE SQUARE CFST BEAM-TO-COLUMN CONNECTION
Authors: Fujinaga Takashi , Clifton Charles G.
Published: February 2025

Concrete-filled steel tubular (CFST) columns are used widely as building structure components because of their good performance. It can be complex, however, to connect beams into CFST columns, especially when rigid beam-to-column connections are required. In order to simplify the fabrication requirements and cost of these connections, a continuous beam type connection through the column is proposed. This can develop the full plastic moment capacity of the beam. In this paper, the experiment testing results of two types of CFST beam-to-column connection specimens are presented and the connection performance and load transfer mechanisms are examined. The continuous beam type connection performance is compared to that of traditionally used through-diaphragm type of connection, which is more complex and demanding to fabricate. Both specimens showed good seismic performance, exhibiting stable hysteretic behavior with high energy absorption. The maximum experimental strength exceeded the calculated value. For a continuous beam type specimen, there is the potential for the column flange to be affected by the local deformation from the steel beam under bending induced beam tension. However, such effects were not observed in practice until late in the test after extensive beam plastic action had occurred.
DESIGN OF BOLTED CONNECTIONS SUBJECT TO TORSION AND SHEAR IN THE ULTIMATE LIMIT STRESS STATE
Authors: Abu-Yosef Mohamed S. , Sayed-Ahmed Ezzeldin Y. , Soliman Emam A.
Published: February 2025

Steel connections transferring axial and shear forces in addition to bending moment and/or torsional moment are widely used in steel structures. Thus, design of such eccentric connections has become the focal point of any researches. Nonetheless, behavior of eccentric connections subjected to shear forces and torsion in the ultimate limit state is still ambiguous. Most design codes of practice still conservatively use the common elastic analysis for design of the said connections even in the ultimate limit states. Yet, there are some exceptions such as the design method proposed by CAN/CSA-S16-14 which gives tabulated design aid for the ultimate limit state design of these connections based on an empirical equation that is derived for ¾ inch diameter A325 bearing type bolts and A36 steel plates. It was argued that results can also be used with a margin of error for other grade bolts of different sizes and steel of other grades. As such, in this paper, the performance of bolted connection subject to shear and torsion is experimentally investigated. The behavior, failure modes and factors affecting both are scrutinized. Twelve connections subject to shear and torsion with different bolts configurations and diameters are experimentally tested to failure. The accuracy of the currently available design equations proposed is compared to the outcomes of these tests.
RESEARCH ON WIND PERFORMANCE AND FIELD EXPERIMENT OF LARGE SCALE COMPLEX SURFACE SPACE TRUSS WITH STEEL PIPE
Authors: Wang Xiuli , Ran Yonghong , Zhang Huvue , Zhu Yanpeng
Published: February 2025

The wind-induced performance response of large-span truss curved roofs is extremely complex and changes obviously under wind load. This paper has taken the large-span steel roof of Liu Zhaike highway toll station as an example to analyze by both numerical simulations and field tests of responses of the steel canopy under wind load. In this case, simulated analysis results using finite element software were calibrated and verified by the field test results. In addition, a new method of large structure field testing was proposed which obtained the internal force and displacement of the canopy structure. Moreover, this paper analyzed and determined the actual stress state of the rectangular pipe truss. Finally, the safety condition of the roof was evaluated based on the monitoring data and the simulation of the finite element model. And the analysis methods provides references for similar engineering field tests, as well as guidance for the operation and maintenance for this project.
STUDY OF THE COMPOSITE ACTION OF HOLLOWCORE PANELS USED IN GIRDER-SLAB SYSTEM
Authors: Roy Nathalie , Parent Serge , Barrière Mélissa
Published: February 2025

Floor construction with precast hollowcore panels produced by Lafarge Precast Edmonton results in a commonly used girder-slab system. Continuity between the elements is ensured by bent rebars and shear studs. Once all these elements are installed, a structural concrete is poured between the reinforced concrete panels and over the entire floor. The extent of composite action between the rigid diaphragm and the steel beams is not known. Therefore, its potential benefit is not taken into account in the current design procedures for the steel structure. The main components of this research project are the following: an experimental program consisting of a series of 6 large-scale shear tests were carried out. The outcome of this research shows that there is a potential for a composite action between a hollowcore plank and a standard hot rolled W shape. It was found that there is enough confinement to develop the steel stud strength when the beam is connected to the precast prestressed concrete panels using a 1/2" shear stud embedded between the planks and under two to three inches of concrete topping.
SEISMIC EVALUATION OF SQUARE HSS BRACES IN SCBF USING REGRESSION ANALYSIS
Authors: Faytarouni Mahmoud , Seker Onur , Akbas Bulent , Shen Jay
Published: February 2025

Since the 1990s, structural engineering practice geared toward the use of hollow structural sections (HSS), notably square HSS, for their economy, and ease of design and construction. According to the AISC Seismic Provisions, during a severe earthquake, these braces could undergo post-buckling axial deformations 10 to 20 times their yielding deformation. However, recent experimental studies indicate that braces made of square HSS, depending on their size, width-to-thickness, and slenderness ratio, are vulnerable to fracture even prior to 10. Therefore, relying on past experimental studies comprised of a few square HSS specimens to develop seismic requirements for SCBF with square HSS could lead to underestimation of the seismic risk. This paper aims to evaluate the fracture risk of braces in existing SCBFs designed in accordance with AISC 341-05 and AISC 341-16 through incremental dynamic analyses (IDA) along with experimentally developed regression model that estimates fracture.
CRACK PATTERN PREDICTION OF LATERALLY LOADED PANELS WITH OPENINGS BASED ON ANN METHOD
Authors: Wang Yongfei , Zhang Yu
Published: February 2025

In this paper, a Back Propagation Neural Network (BPNN) is used to predict crack pattern for masonry panels with opening subjected to lateral loading. The cellular automata method is used to digitalize the panels, including two steps-dividing a panel into a certain number of cells and calculating cell state values by use of a Von Neumann neighborhood model. These digitalized values are used as input data of NN model, respectively. All the experimental data is collected, including panel configuration, material property, opening ratio and location, state values, and crack pattern. The NN model is trained repeatedly, taking part of the data as a training set, to determine parameters, and the rest of the data is taken to check the model. Well-trained NN models can predict the crack pattern of any other panel. The results show that NN method is suitable for prediction of crack pattern. Comparing the two ways of prediction, the Fragility Coefficient Method gets a more precise pattern. The predicted cracks are distributed successively in some specific areas, especially in high similarity, compared with experimental crack pattern.
EFFECT OF SITE AMPLIFICATION ON SEISMIC SAFETY EVALUATION OF FLYOVER PIER
Authors: Mukhlis Mohammad Raihan , Bhuiyan Md. Abdur Rahman
Published: February 2025

Bangladesh is a developing country in which a lot of multi-span simply/continuous supported flyovers are being constructed in its major cities. Being situated in a seismically active region, seismic safety evaluation of flyovers is essential for seismic risk reduction. Effects of site amplification on seismic safety evaluation of flyover piers are the main concern of this study. In this regard, failure mode, lateral strength and displacement ductility of piers of a typical multi-span simply supported flyover have been evaluated by Japan Road Association (JRA) recommended guidelines, with and without considering site amplification. Ultimate flexural strengths of piers have been computed using the pushover analysis results. Shear capacity of piers have been calculated using the guidelines of JRA. Lateral strengths have been determined depending on the failure modes of the piers. Displacement ductility of piers has been computed using yield and ultimate displacements of the piers obtained from the pushover analysis results. Selected earthquake time history is used in seismic safety evaluation of the flyover piers. Finally, the ductility design method is used to conduct the seismic safety evaluation of the piers with and without considering site amplification. From the numerical results, it has been revealed that the effects of site amplification on seismic safety evaluation of bridge structures should be carefully taken into account.
BEHAVIOR OF CONTINUOUS CONCRETE BEAMS REINFORCED WITH BASALT BARS
Authors: Aragao Almeida Junior Salvio , Parvin Azadeh
Published: February 2025

The use of fiber-reinforced polymer (FRP) for reinforcement and retrofit of structures has become common in recent years. Although considerable research exists on carbon, glass, and aramid fibers, new materials continue to emerge, requiring new knowledge to optimize their use and safe design. This study analyzed the behavior of continuous beams reinforced with FRP bars. The parameters studied were concrete type (normal-strength concrete (NSC) and ultra-high-performance fiber-reinforced concrete (UHPFRC)), fiber material (carbon, glass, and basalt), and environmental exposure (acid, alkaline, and saline environments). Finite element (FE) beam models were developed and validated with published experimental data. The validated models were used to study the aforementioned parameters. Although the basalt fibers provoked higher displacements when compared to carbon and glass fibers, they also provided better bond with the concrete and higher tensile strength, allowing the beams to reach higher load capacity. Exposure to aggressive environments diminished the adhesion between GFRP and BFRP bars and the concrete, but the reduction was not sufficient to initiate the debonding and the failure was governed by FRP bars rupture. However, it was concluded that the load-displacement response was not affected much by the environmental exposure. The UHPFRC provided superior bond strength between concrete and the reinforcement bars, which assured rupture of the fibers in these beams as well. The use of UHPFRC also resulted in an increase in the beams’ load carrying capacity.
COLLAPSE AND BUCKLING OF STAINLESS STEEL PRESTRESSED STAYED COLUMNS
Authors: Machacek Josef , Pichal Radek
Published: February 2025

Buckling and collapse of stainless steel elements loaded in compression are studied experimentally and numerically. Based on four tests of single crossarm stayed columns the numerical analysis using ANSYS software package is validated and presented in a detail. First, for a completeness, the study refers to columns with one central crossarm, but the main emphasis is devoted to columns with two crossarms located in the thirds of the element length. The analysis employed geometrically and materially nonlinear analysis (GMNIA) to respect a change of inner energy during buckling of an "ideal" (perfect) column, initial deflections of an "imperfect" column (covering various initial deflection modes and amplitude values) and nonlinear stress-strain relationship belonging to stainless steel material. The results cover both critical buckling and maximal collapse loads of the columns in compression. Finally, the important comparisons of the load capacities concerning stayed columns in compression with one/two crossarms and ratios of critical/maximal loadings, elastic/inelastic material and fixed/sliding support of the stays at the crossarms are provided. Conclusions comprise evaluation of these results and principal recommendations for the design of stayed columns.
A PULL-DOWN DYNAMIC ANALYSIS OF TWO-SPAN STEEL FRAMES SUBJECTED TO PROGRESSIVE COLLAPSE
Authors: Esfandiari Mohammadjavad , Urgessa Girum
Published: February 2025

Progressive collapse, also known as disproportionate collapse, describes a chain reaction of structural element failures in which a primary structural element failure results in the failure of adjoining structural elements. It eventually causes widespread structural damages and a disproportionate collapse. While high level finite-element models incorporating non-linear dynamic analysis will produce more realistic results in progressive collapse scenarios, they are computationally time consuming. Therefore, the development of a non-linear time history pull-down model that is validated with experimental results would be beneficial for producing acceptable and efficient design solutions, particularly for practicing structural engineers. In this paper, a non-linear time history pull-down model of a two-span steel frame is analyzed in ETABS. The ETABS model results are compared with experimental results of two steel frames with two-spans conducted by the National Institute of Standards and Technology (NIST). The NIST experiments include beam-column assemblies from the second-floor framing system of a ten-story building and each span is 20 feet long. The numerical results from ETABS pull-down analysis showed good agreement with the results from the NIST experimental study.
AMASS: ADVANCED MANUFACTURING FOR THE ASSEMBLY OF STRUCTURAL STEEL
Authors: Schultz Arturo E. , Le Jia-Liang , Shemshadian Mohamed E. , Labbane Ramzi , Laefer Debra F. , Al-Sabah Salam , Truong-Hong Linh , Huynh Minh , McGetrick Patrick , Martin Tony , Matis Pantelis
Published: February 2025

This paper describes a collaborative project between the US, Ireland, and Northern Ireland (UK) to investigate advanced manufacturing cutting techniques for the creation of a new class of intermeshed steel connections that rely on neither welding nor bolting. To date, advanced manufacturing equipment has only been used to accelerate traditional processes for cutting sheet metal or other conventional fabrication activities. Such approaches have not capitalized on the equipment's full potential. This project lays the groundwork to transform the steel building construction industry by investigating the underlying science and engineering precepts for intermeshed connections created from precise, volumetric cutting. The proposed system enhances the integration between design, fabrication, installation and maintenance through building information modeling platforms to implement advanced connections. Fully automated, precise, volumetric cutting of open steel sections introduces intellectual challenges regarding the load-transfer mechanisms and failure modes for intermeshed connections. The research activity addresses knowledge gaps concerning the load resistance and design of steel systems with intermeshed connections. Physical tests, finite element simulation and multi-scale modeling are being used to investigate the mechanics of intermeshed connections including stress and strain concentrations, fracture potential and failure modes, and to optimize connection geometry.
OPTIMIZATION PARAMETER SETS FOR SUSTAINABLE CONCRETE IN TUNNELS
Authors: Strömberg Larissa , Löfsjögård Malin , Ansell Anders , Hintze Staffan
Published: February 2025

Public and private clients are beginning to set complex optimization requirements, taking into consideration environmental and cost-efficiency parameters over the built construction's lifetime. The early design process is currently irreversible, and this makes it difficult to change a concrete structure in the later detailed design stage, when more accurate information is available regarding environmental impact and life-cycle costs. There is a dilemma in complying with existing standards to achieve technical requirements while optimizing a concrete structure in order to reduce the climate impact. The long-term goal of the project is to develop a new theoretical concept for dynamic optimization strategies which can be applicable to the early design, the client-requirement preparation, the detailed design, the production and the follow-up stages. This paper presents the results of the up-start phase of the project. The work has focused on the identification of current practice regarding clients' requirements for technical, environmental and cost-efficiency parameters. An analysis of these requirements with sprayed concrete (shotcrete) in a number of ongoing projects has led to the identification of optimization parameter sets. The project has also shown how the physical values of those parameters can be collected from existing statistics, experience recovery databases and previous project requirements, or calculated according to standardized methods and tools. The concept developed will be used in a demonstrative modeling in the next project step.
FLEXURAL BEHAVIOR OF HIGH STRENGTH GEO-POLYMER CONCRETE BEAMS
Authors: Bhikshma Vankudothu , Promodkumar Kandiraju , Panduranghiah Putta
Published: February 2025

The demand for concrete is increasing day by day. As the consumption of cement is increased, environmental issues arise due to the release of CO2 during the manufacturing of cement. The objective of this research work is to produce a pollution free concrete with a combination of fly ash and GGBS (Ground granulated blast furnace slag) and without the use of cement. In this paper an attempt was made to study the mechanical properties of high strength geo-polymer concrete of grade M60 using GGBS, fly ash and micro silica. The testing program was planned for the mechanical properties of geo-polymer concrete and flexural behavior of corresponding beams. The experimental results indicated that the geo-polymer concrete M60 grade has a compressive strength of 70.45 MPa at the age of 28 days cured at ambient condition. Further, flexural strength and split tensile strengths for M60 grade high strength geo-polymer concrete at 28 days were observed to be 5.45 MPa and 3.63 MPa respectively. The modulus of elasticity was higher than the theoretical value proposed by IS 456-2000. It was also observed that the load carrying capacity of M60 grade high strength geo-polymer concrete found to be more than corresponding grade conventional concrete. The load-deflection, moment-curvature relationships were studied. The experimental results were encouraging to continue for further research in the area high strength geo-polymer concrete.
REUSE OF GLASS AND CLAY BRICK WASTES AS SUBSTITUTE FOR NATURAL AGGREGATE IN GREEN CONCRETE
Authors: Olofinnade Oluwarotimi , Ede Anthony , Ndambuki Julius , Opeyemi Ayanfe
Published: February 2025

Utilization of recycled waste materials in making concrete is identified as a sustainable means of managing wastes, thereby reducing the energy consumption, preserving the environment and conserving of natural resources from depletion. Researchers referred to this type of concrete as "green" concrete. This study examines the possible reusing of crushed waste glass as partial and complete substitute for natural aggregates in production of moderate strength green concrete with the addition of ground clay brick as admixture. The clay bricks were obtained as generated wastes from the ceramic and brick producing factory, while the glass wastes were sourced from dump sites and waste collection points within Ota, Nigeria. The waste glass varied from 25%-100% in steps of 25%, and the ground clay brick was added in 10%, 15% and 20% by mass of Portland cement into the concrete mixes. Tests, which include workability and characteristics strength were carried out on the concrete specimens. Microstructural examination was performed on selected concrete specimens. Results indicate reduction in workability with increased waste glass and clay brick powder content. Moreover, the characteristic compressive strength of the concrete specimens increased with curing age, however, concrete mixes containing 10% clay brick powder and 25% waste glass aggregate showed significant improvement in strength at curing age of 28 days than the control concrete.
THEORETICAL ASSESSMENT OF IMPACTS OF PROPERTY RIGHTS ON EXISTING RECONSTRUCTION AND DEVELOPMENT PROGRAM HOUSES
Authors: Mashwama Nokulunga , Aigbavboa Clinton
Published: February 2025

The paper assesses the impacts of property right on low-cost housing and the solutions to address the challenges of property rights on low-cost housing. A literature review is the primary research method on the subject matter to find answers to impacts of property rights on affordable housing. The basis of the study is a general literature review (locally and internationally) published by other researchers on the similar study. The study indicated that enhanced political voice and political accountability has an impact on improving the prospects for secure property rights. Moreover, influence and supports the notion that the rule of law, in providing legal security for property rights, is an enabling condition for economic growth. Furthermore, if governments of developing countries provide real property ownership with clear titles and rights enforceable by law, then poor people will be able to use their assets to obtain credit which can be employed in productive activities, and countries could lever themselves and their poor inhabitants out of poverty. The research will make contribution to type of land reform, which lead to sustainable development through land titling, a reduction in the probability of being evicted, or otherwise losing land rights and provide land users with greater assurance that they will enjoy fruits of their labor and investment, thereby encouraging them to make long-term investments for sustainable use of their properties.
Paměť oboru: Šmilauer – Hausenblas – Stich 2023 podruhé
Authors: Mareš Petr
Published: February 2025

Editorial
Český furor orthographicus? Role Alexandra Sticha ve sporech o pravopis prizmatem (historické) sociolingvistiky
Authors: Fidlerová Alena A.
Published: February 2025

The aim of the paper is to present Alexandr Stich’s understanding of orthography, as it can be observed in his scholarly and journalistic articles and in the argumentation he and his opponents used; subsequently, this description serves as a basis for a short reflection on the nature of orthography, as viewed by some researchers in the (historical) sociolinguistics of spelling, and on the strengths and weaknesses of Stich’s approach. Given Stich’s grounding in the tradition of the Prague School, I begin with a brief overview of the functional-structuralist approach to orthography. Then, I discuss individual relevant articles Stich published or participated in. Since most of them were written in response to some external stimulus, usually an article or a book with which he disagreed, I also touch on these texts and the argumentation they contain. Most space is devoted to the controversy stirred up by the preparation and publication of the 1993 edition of the Rules of Czech Orthography. I show what Stich’s position was, which arguments he most often used and how his argumentation differed from that of his opponents. Consequently, I summarize the main features of Stich’s understanding of the nature and function of orthography and whether or not they changed over the years. Finally, I briefly introduce current sociocultural and sociopolitical approaches to orthography, developed within the (historical) sociolinguistics of spelling since roughly the 1990s. On their basis, I point out the limitations of Stich’s (or functional-structuralist) conception of orthography and its blind spots, and I suggest that the sociolinguistic interpretation of what actually happened during the 1993 controversy appears more plausible.
Materiály k problematice raně novověké literatury v osobním fondu Alexandra Sticha
Authors: Sládek Miloš
Published: February 2025

The paper deals with texts related to early modern literature from the personal collection of Alexandr Stich stored in the National Literature Memorial in Prague. The article briefly mentions small prints and photographs related to the mentioned issue. The author pays the main attention to Stich’s manuscripts, especially unpublished articles and notes. Undoubtedly, Stich’s efforts to synthesize the literary history of the Czech early modern period, which are represented in the fund only by a manuscript torso, are interesting. Stich’s editorial proposals from the late 1980s, partially realized only at the turn of the century in completely different political and cultural contexts, also deserve attention. In addition to linguistic and literary methods, sociological approaches are also typical of Stich’s last years. Stich remarkably foreshadowed the further development of research, after all, he himself influenced it by directing his students.
K otázce stylu českých a polských veřejných nápisů
Authors: Charciarek Andrzej
Published: February 2025

The article analyzes Polish and Czech public notices from the perspective of their stylistic features. It focuses on similarities and differences between public notices and specific administrative documents. Much attention is paid to two terms: notice/notification and rules/regulations, terms denoting both public notices and documents. The analysis concentrates on the first type and is illustrated with authentic notices found in the public spaces of Polish and Czech cities.
Produkce vydavatelství Romaňi čhib: Lingvoliterární aspekty jedné významné vlny romského národního obrození
Authors: Červenka Jan
Published: February 2025

Roma began to emancipate themselves more significantly as a non-territorial minority in the former Czechoslovakia in the second half of the 20th century. Emancipation has taken place in various successive and parallel waves. The article presents one of these waves, centred around the Romaňi čhib publishing house and the personalities of Margita Reiznerová and Gejza Demeter. The production of the publishing house (whose name meant ‘Romani Language’) differed from other emancipatory activities in its conception of Romani as the primary communicative language of the national minority. The magazine called Romano gendalos (‘Romani Mirror’) published texts in Romani with a minimum of language contact products, and the books published were monolingual, only in Romani. The author traces the origins, the peak period in 1992 and the gradual demise of this interesting ethno-emancipatory project.
ASSESSMENT OF THE POSSIBILITY OF INTRODUCING A SOLID PROPELLANT ACCELERATOR P230 OF THE ARIANE 5 ROCKET AS A HELMHOLTZ RESONATOR
Authors:   Oles Honchar Dnipro National University, SOKOL G. I. , KOZIN V. S. ,   Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and State Space Agency of Ukraine
Published: February 2025

The problem of harmful resonant pressure fluctuations in solid-propellant accelerators during the initial acceleration of the Ariane 5
space system is considered. An assumption was made regarding the connection of these fluctuations with changes in the geometric
characteristics of the P230 accelerators due to the formation of cavities in them according to the burnout regimes filled with solid rocket
propellant combustion products. The volumes of cavities formed during propellant combustion were calculated. The engine scheme that
arose after the first part of the charge burned out is considered. It is obvious that the shape of the cavity can be approximated by the
Helmholtz resonator model. It is also taken into account that the gradual heating of the upper layers of solid propellant and the associ-
ated changes in the wave resistance of the propellant play a role in the appearance of pressure pulsations in the combustion chamber
(CC) of a rocket engine. This leads to the rise of resonant phenomena in the formed cavities. As a result of considering various resonator
systems, the Helmholtz resonator model, which is most suitable for the computational explanation of pressure pulsations, was chosen
to describe the physical model of resonance phenomena. Calculations using this model yielded the same frequency as in the results of
measurements during the flight operation of the Ariane 5 space system. Next, the direction for solving the problem of reducing resonant
oscillations in the combustion chamber is proposed.
A differenciált pajzsmirigyrák rizikója mint első és második primer tumor
Authors: Kiss András , Szili Balázs , Bakos Bence , Tóbiás Bálint , Balla Bernadett , Takács István , Lakatos Péter , Kósa János
Published: February 2025

Régóta ismert, hogy differenciált pajzsmirigyrákok után – az általános
populációhoz képest – gyakoribbak bizonyos második primer tumorok. Emellett
egyes malignus betegségek után a vártnál gyakrabban fordul elő pajzsmirigyrák
második tumorként. Áttekintő közleményünkben bemutatjuk a differenciált
pajzsmirigyrák kapcsolatát az egyéb primer malignus betegségekkel. Kitérünk a
pajzsmirigyrákok után előforduló második primer malignitások gyakoriságára,
illetve elemezzük a férfiakban és nőkben előforduló leggyakoribb daganattípusok
után kialakuló második primer pajzsmirigyrák rizikóját a legújabb szakirodalom
alapján. Mivel a kettős tumorok kialakulását számos tényező befolyásolja –
genetikai hajlam, életmódbeli és környezeti tényezők, az első tumorra
alkalmazott kezelés, érzékelési torzítás –, a második primer malignitások
kockázatára a különböző közleményekben eltérő értékeket találunk. Mindezzel
együtt megállapíthatjuk, hogy az átlagnépességhez képest pajzsmirigyrák után
gyakoribb az emlő-, prosztata-, vastagbél-, végbél- és veserák, valamint
bizonyos hematológiai malignitások. Pajzsmirigyrák gyakrabban jelenik meg az
emlő-, prosztata-, vastagbél-, végbél-, tüdő-, vese- és húgyhólyagrák, valamint
bizonyos hematológiai malignitások és neuroblastoma után. Ezek alapján
pajzsmirigyrák után hosszú klinikai követés javasolt az esetleg kialakuló
második primer malignitás korai felismerésére, a betegek részéről pedig az
általános népességnek ajánlott rákszűrések, illetve az előírt orvosi vizitek
fokozott betartása javasolt. Orv Hetil. 2025; 166(7): 253–262.
Performance of Publicly Quoted Agricultural Ventures in Nigeria: The Case of Presco PLC and the Okomu Oil Palm Company PLC
Authors:   Cambridge International Advanced Level Programme, Word of Faith Schools, G.R.A, Benin City, Nigeria, Adade B.F. , Ada-Okungbowa C.I. ,   Department of Agricultural Economics and Extension Services, University of Benin, Benin City
Published: February 2025

Agribusinesses are known to be drivers of economic development in developing nations. Yet little research has been carried out to examine the historical performance (productivity and financial) of oil palm nucleus estates in Nigeria. This study examines how publicly quoted oil palm companies in Nigeria performed over the period, 2011 to 2016. Several indicators of company success (including productivity measures, financial ratios and balance sheet/income statement items) were considered. The data were analyzed using descriptive and inferential statistics (to compare the performance of the two companies). DuPont analysis was also carried out. The study found that both companies performed well in terms of financial ratios related to profitability, liquidity, market, and creditworthiness. The DuPont analysis showed that the return on equity for Presco was mainly due to higher net profit margin while that of Okomu was due to higher total asset turnover; weakness of Presco in the inability to use its assets to generate sales was made up for by higher use of debt in its capital structure. Therefore, it is recommended that Okomu and Presco PLC should work on their profit margin and debt levels respectively to boost return on equity. The Nigerian public should also invest in both companies since they are performing well.