Abstract: This study has examined the design proposal for a support structure for a rainwater storage tank, utilizing CAD/CAE software with computational numerical analysis. These tools predict how elements will behave under specific conditions without physical construction. The necessity arises from the importance of developing the entire rainwater harvesting system to offer a sustainable water supply alternative. To this end, a storage capacity of 500 liters was determined based on locally available plastic tanks, considering the dimensions and weight the structure needs to support. 3D modeling utilized a 50 mm (2 in) square steel pipe discretized through meshing. Validation of this process achieved a skewness of 0.2401 with 414 651 elements and 601 334 nodes, defining the corresponding initial and boundary conditions. Von Mises stress measured 189.5 MPa, below the yield limit for structural steel, with structural element deformation not exceeding 0.83 mm. Design validation was accomplished through safety factor analysis, yielding a value of 1.746, closely aligning with recommended values for support structures.

Resumen: Esta investigación ha evaluado la viabilidad de un diseño para una estructura de soporte destinada a un tanque de almacenamiento de agua pluvial. Se utilizó software CAD/CAE para llevar a cabo un análisis numérico computacional debido a que estas herramientas permiten predecir comportamientos de elementos sometidos a condiciones específicas, sin necesidad de construcción. La necesidad de este diseño surge de la importancia de desarrollar un sistema integral para la captación de agua de lluvia, como una alternativa sostenible para el suministro de agua. Se estableció una capacidad de almacenamiento de 500 litros, considerando los tanques plásticos disponibles en el mercado local, para determinar las dimensiones y la carga que la estructura debe soportar. El modelado tridimensional se realizó utilizando una tubería cuadrada de acero estructural de 50 mm (2 plg), la cual fue discretizada mediante un mallado. Este proceso se validó alcanzando skewness de 0.2401, con un total de 414 651 elementos y 601 334 nodos, y se definieron las condiciones iniciales y de contorno correspondientes. El esfuerzo de Von Mises obtenido fue de 189.5 MPa, lo cual está por debajo del límite de fluencia para el acero estructural. Además, la deformación en los elementos estructurales no superó los 0.83 mm. El diseño se validó mediante un análisis del factor de seguridad, el cual fue de 1.746, aproximándose al valor recomendado para estructuras de soporte.

Cappadocia is not only a region of Turkey with historical and touristic importance. During the cutting and processing of volcanic tuff, quarries in this region release large amounts of tuff into the environment that is viewed as waste. The release of this waste constitutes an economic loss and contributes to environmental pollution. However, through experimentation with deformation, weight per unit of volume, water absorption, uniaxial compression strength, modulus of elasticity, and point load strength index, volcanic tuff and marble dust composite materials can be produced for use in the building sector. In this study it was observed that, as the percentage of volcanic tuff dust in the mixture increased, the water absorption rate of the material increased, and uniaxial compression strength and point load strength decreased. The produced composite samples used in this study were kept for a predetermined number of times per day, and no deformation in the surface characteristics of the materials was observed. In a statistical parameter analysis, averages, variances, standard deviations, coefficients of variation, and skewness coefficients were calculated. Covariance changes between experimental parameters were also determined. In this study, two types of volcanic tuff dust, that is, yellow and red, were produced during the production of tuff-marble dust composite material. When the percentage of either type of volcanic tuff dust was increased, an increase in water absorption was observed. It was also observed that when the percentage of volcanic tuff dust was increased, uniaxial compressive strength and point load strength decreased. Furthermore, the physical and mechanical properties of the materials obtained by mixing different colored tuff powders and marble powders in different proportions were evaluated using statistical parameter analysis.

Underground mining in high rock-stress environments can induce unanticipated dynamic rockmass deformation, posing a serious risk to the workforce. Data collected by seismic networks are imperative for the design-as-you-mine process. Often an inappropriate assessment of the seismic hazard is done when unnecessary data are included in analytical techniques, particularly short-term time frames. Depending on the methodology or application of data analysis and interpretation, some of the information may not be relevant and even detract from the objective. By using the spatial event clusters associated with active workplaces to define the shape and size of the polygons for data selection for subsequent analysis, a problematic subjective component can be eliminated. The mining of tabular reefs in South Africa, be they gold- or platinum group metals, is very extensive, and underground workplaces are often widespread. Production stoppages are very costly, especially for marginal mines, so there is just cause not to evacuate an entire operation's workforce following the occurrence of a large mining-induced seismic event. A rationale based on the damaging peak particle velocities (PPV) of the past seismicity can exclude the unaffected underground personnel and allow a quick orderly withdrawal where required. Micro-deformation may precede rockbursting, which can occur on-shift close to the workface. A mine-wide array of geophones suitable for the accurate location and analysis of seismicity may not be able to detect these higher-frequency emissions. Inexpensive but fit-for-purpose accelerometers, providing real-time, continuous measurement of acoustic rockmass deformation near the workplace, integrated through underground and surface communications networks, are shown to record 'rock-talk', clearly distinguishable from the instrument background noise, which can be in the order of hours leading up to an imminent damaging seismic event.

ABSTRACT Purpose: Although the orthokeratology effects on corneal biomechanics have been proven with clinical trials, reports of stiffness parameter change are scarce. This study investigated the short-term orthokeratology effects in pediatric myopia and compared stiffness parameter changes to those published in recent clinical investigations. This prospective study aimed to investigate corneal biomechanics changes induced by short-term overnight orthokeratology treatment, focusing on stiffness parameter at A1 and stress-strain index Methods: Twenty-six children aged 8 to 18 were included in this study using orthokeratology lenses for two different durations: 1 day and 1 week. Corneal biomechanics were assessed using corneal visualization (Corvis) Scheimpflug technology. Measurements were taken at baseline and after each wearing session. Changes in corneal stiffness parameters and corneal curvature were analyzed. Results: All parameters changed significantly after 1 week of lens wear (p<0.05), except for velocity of corneal apex at the first and second applanation times highest concavity time, radius, stiffness parameter at A1 and stress-strain index. After 1 day, central corneal thickness, first applanation time, second applanation time, deformation amplitude ratio (2 mm), and Corvis biomechanical index (CBI) remained stable (p>0.05). After 1 week, central corneal thickness and first applanation time decreased, whereas second applanation time, deformation amplitude ratio, and Corvis Biomechanical Index significantly increased. With intraocular pressure and central corneal thickness as control variables, no significant correlation was found between stress-strain index and curvature changes (p>0.05). With age as the control variable, no significant correlation was found between stress-strain index and curvature changes (p>0.05). Conclusions: Short-term orthokeratology treatment induced notable changes in several corneal biomechanical parameters. Stiffness parameter at A1 and stress-strain index are unaffected by increasing lens wear duration and do not influence the orthokeratology effect.

Abstract This work aimed to develop biodegradable films from yellow passion fruit (Passiflora edulis f. flavicarpa) peel flour. The Central Composite Rotational Design was used in a total of 11 tests, in which the independent variables were the concentrations of starch and glycerol, characterized with regard to physical, mechanical and barrier properties. The films were classified as soluble and showed low permeability to water vapor. The tensile strength, elastic modulus and deformation rate were directly related to the concentration of starch and glycerol. The film of test 7 had the best characterization results; therefore, it was analyzed for biodegradability. As for biodegradability, the film obtained an average mass loss of 92.77 ± 4.28%, being a great alternative to the use of non-biodegradable polymers. The films showed acceptable degree of plasticization, which was favored by intermolecular interactions between the components of the flour, starch and glycerol.

Abstract This article investigates the buckling and free vibration behavior of bio-inspired helicoid laminated composite (BiHLC) plates resting on a Pasternak foundation (PF) using the meshfree moving Kriging (MK) method for the first time. In this study, the MK method leverages Reddy's first-order shear deformation theory (FSDT) for analysis of the mechanical behavior of plates. The PF is characterized by two stiffness parameters: spring stiffness k 1 and shear stiffness k 2. A key advantage of the MK interpolation is its Kronecker's delta property, enabling direct enforcement of boundary conditions (BC). Unlike original MK method, this approach does not require pre-defining the correlation parameter, which can influence approximation accuracy. The governing equations are derived using Hamilton's principle. A thorough analysis is conducted to understand how the helicoidal layup scheme, geometrical parameters, BC, and the foundation's stiffness parameters influence the critical buckling loads and natural frequencies of BiHLC plates.

ABSTRACT Deformation intensity analysis for mechanical parts are very important data for machine design. For farm machines, these parameters present difficulties for determination due to its particularities. The Machinery industry searches for advanced technologies to determine the mechanical behavior of parts. This article shows the analysis of the reliability in the application of the laser triangulation technique (LTT) to determine the deformation of the mechanical elements of farm machines. A flat cutting disc with standardized dimension was selected as the object of study, as it is commonly used in farm machines, exhibiting a simple geometry made of steel, making the analysis procedure easier both for experimental execution and for data validation. Displacements of 1.0 mm to 10 mm were applied on the specimen. The theoretical behavior of specimen displacement was defined by finite element modelling with same condition of loading and dimension to compare the generated data by the experimental tests. Results indicated a displacement with maximum variation of 2.56% between experimental data and theoretical results and were considered satisfactory. LTT was able to determine deformation curve behavior of machine elements. It was concluded that Laser Triangulation Technique (LTT) was satisfactory to determine the deformation of a specimen.

ABSTRACT Objective: To evaluate the surface defects in Wave One Gold and Jizai rotary files after 1 and 3 uses. Material and Methods: Ninety-six resin blocks with stimulated canals and 12 files per system were used. The files were pre-examined under scanning electron microscopy (SEM) to exclude files with pre-existing cracks and craters. Instrumentation and SEM evaluation of the files were performed after 1 and 3 uses, respectively. Two independent operators analyzed the images, and scoring was carried out for each file's coronal, middle, and apical thirds. The surface defects at different thirds of the file systems were analyzed using the Chi-Square test and Kendel Tau’s test. Results: After one use, both the file systems did not produce any significant surface defects in the coronal, middle, and apical thirds. However, after three uses, there was minor plastic deformation in the coronal and middle thirds of the Wave One Gold file system. Jizai file system did not produce any surface defects in the coronal, middle, and apical thirds. Conclusion: After one use, no surface defects were created in Wave One gold and Jizai rotary files. Wave One Gold exhibited more significant surface defects after three uses in the coronal and middle thirds.

Resumen Para el modelamiento de estructuras, la hipótesis de diafragma rígido (DR) es empleada frecuentemente en el diseño sismorresistente, sin considerar si dicha hipótesis refleja una respuesta real de la edificación ante cargas de sismo. Desde una concepción arquitectónica, las edificaciones con tipologías de plantas irregulares satisfacen necesidades espaciales, funcionales y bioclimáticas; sin embargo, dichas estructuras se contraponen con su desempeño sísmico por tener respuestas diferentes. Además, se debe asumir una hipótesis para la losa de entrepiso que puede ser diafragma rígido (DR) o diafragma flexible (DF). Por lo tanto, es necesario conocer las respuestas lineales de estructuras con plantas irregulares. El objetivo del presente estudio es evaluar las configuraciones irregulares en plantas tipo L, H, T y U sobre el comportamiento sísmico de estructuras de ocho niveles, considerando las hipótesis de DR y DF. A partir de las respuestas globales y locales, se determinó que los casos de estudio con DF presentaron periodos de vibración más largos, que generaron mayores deflexiones de las estructuras, provocados por la deformación de la losa en su plano. Sin embargo, los valores de las fuerzas cortantes con DF fueron menores en comparación con los modelos con DR, debido a que la losa de entrepiso se deformó en su plano, lo que repercutió en la disminución del coeficiente de amplificación sísmica (C). Así, también, las tipologías L, T y U presentaron mayores demandas sísmicas, desplazamientos laterales y aceleraciones en los bordes en comparación al modelo H, que presentó desplazamientos laterales menores y uniformes.

Abstract For the modeling of structures, the hypothesis of a rigid diaphragm (DR) is frequently employed in earthquake-resistant design, without considering whether this hypothesis accurately reflects the building’s actual response to seismic loads. From an architectural standpoint, buildings with irregular floor plan typologies fulfill spatial, functional, and bioclimatic needs. However, these structures contradict their seismic performance due to their differing responses. Additionally, a hypothesis must be assumed for the floor slab, which can be a rigid diaphragm (DR) or a flexible diaphragm (DF). Therefore, it is essential to understand the linear responses of structures with irregular floor plans. The objective of this study is to evaluate irregular configurations in L, H, T, and U-type floor plans regarding the seismic behavior of 8-story structures, considering both DR and DF hypotheses. Based on global and local responses, it was determined that the DF study cases exhibited longer vibration periods, resulting in greater deflections of the structures caused by the deformation of the slab in its plane. However, shear force values with DF were lower compared to DR models, due to the slab deforming in its plane, resulting in a reduction of the seismic amplification coefficient (C). Additionally, L, T, and U typologies showed higher seismic demands, lateral displacements, and accelerations at the edges compared to the H model, which exhibited smaller and uniform lateral displacements.

Resumen Las fracturas mandibulares poseen una alta prevalencia en el territorio maxilofacial, requiriendo, en su mayoría, resolución quirúrgica. El Gold Standard corresponde a la reducción abierta con osteosíntesis con placas de titanio. Nuevos materiales biocompatibles han sido aplicados con el fin de subsanar las complicaciones y desventajas de las placas de titanio, surgiendo las placas de osteosíntesis reabsorbibles. Conocer la efectividad de las placas de titanio y placas de osteosíntesis reabsorbibles en el tratamiento de fracturas mandibulares permite determinar la necesidad de invertir en nuevas técnicas con resultados predecibles. Describir la efectividad del uso de placas de titanio y placas de osteosíntesis reabsorbibles en el tratamiento de fracturas mandibulares. Durante agosto del año 2023, se realizó una revisión sistemática exploratoria de la literatura disponible desde 2018 sobre el uso de placas de osteosíntesis reabsorbibles en fracturas mandibulares, empleándose los buscadores PubMed, Scopus y WOS incluyendo estudios en inglés o español. Se obtuvieron 227 artículos. Después de la revisión de título y resumen, 29 fueron incluidos para lectura de texto completo, se descartaron 9 duplicados, 10 fueron descartados por criterios de exclusión, quedando en total 10 artículos en este estudio. Autores relatan menor desplazamiento de la superficie de contacto de las placas de titanio en los segmentos fracturados, por una mayor área de presión superficial, rigidez y fuerza de carga. Las placas de osteosíntesis reabsorbibles son más flexibles y están sujetas a mayor deformación ante fuerzas masticatorias de gran magnitud, pudiendo generar apertura de la fractura, desplazamiento de segmentos óseos. Se analizaron las complicaciones post operatorias y no presentan diferencias estadísticamente significativas. Los dispositivos de titanio y reabsorbibles no difirieron en términos de comportamiento biomecánico y complicaciones postquirúrgicas en el tratamiento de fracturas mandibulares. Faltan nuevos estudios que comparen ambas placas en fracturas mandibulares.

Abstract Mandibular fractures have a high prevalence in the maxillofacial region, often requiring surgical intervention. The gold standard for treatment involves open reduction with osteosynthesis using titanium plates. New biocompatible materials have been applied to address the complications and disadvantages of titanium plates, leading to the emergence of absorbable osteosynthesis plates. Understanding the effectiveness of titanium plates and absorbable osteosynthesis plates in the treatment of mandibular fractures helps determine the need to invest in new techniques with predictable outcomes. To describe the effectiveness of using titanium plates and absorbable osteosynthesis plates in the treatment of mandibular fractures. In August 2023, an exploratory systematic review of the available literature since 2018 on the use of absorbable osteosynthesis plates in mandibular fractures was conducted. PubMed, Scopus, and WOS were searched, including studies in English or Spanish. A total of 227 articles were obtained. After reviewing titles and abstracts, 29 articles were included for full-text reading. Nine duplicates were discarded, and 10 were excluded based on predefined criteria, resulting in a total of 10 articles for this study. Authors report that titanium plates exhibit less displacement of the contact surface in fractured segments due to a larger surface area, rigidity, and load-bearing capacity. Absorbable osteosynthesis plates are more flexible but are susceptible to greater deformation under significant masticatory forces, potentially leading to fracture opening and displacement of bone segments. Postoperative complications were analyzed, and no statistically significant differences were found. Titanium and absorbable devices did not differ in terms of biomechanical behavior and postoperative complications in the treatment of mandibular fractures. Further studies comparing both types of plates in mandibular fractures are needed.

RESUMEN En la Fm. Arroyo Cangre ubicada en la Faja Cangre, al norte de la falla Pinar en el occidente de Cuba, están ampliamente desarrolladas las vetas de cuarzo, principalmente en metaareniscas. El objetivo de este trabajo fue caracterizar las vetas, para lo cual se consideró principalmente la medición de estructuras (vetas, planos de estratificación y foliaciones). Se caracterizaron cualitativa y cuantitativamente 84 vetas, evaluando: estructura interna, relación con la estratificación (longitudinal, oblicua y transversal), mineralogía, espesor, tipo de deformación a la que se asocian, estilo geométrico, elementos de yacencia, litología de caja, relación de corte, halos de alteración y elementos de yacencia. El análisis cualitativo de las vetas en su relación geométrica-cinemática y sus relaciones con los diferentes períodos deformacionales que afectaron el área, apunta a que las vetas longitudinales pueden estar asociadas con el transporte tectónico del segundo periodo deformacional (P2) bajo condiciones distensivas, al igual que las vetas transversales y una parte de las oblicuas. Las otras dos familias de vetas oblicuas se formaron a inicios del último período (P4) o a lo largo de este, asociadas al orógeno extrusivo y a la configuración definitiva de la zona.

ABSTRACT The Arroyo Cangre Formation located at La Faja Cangre, by the north of Pinar fault by the western Cuba, has a wide presence of quartz veins, mainly in meta-sandstone. The paper aims to characterize the veins mainly by measuring structures (veins, stratification planes and foliations). Eighty-four veins were characterized qualitatively and quantitatively by evaluating the internal structure; the relationship with stratification (longitudinal, oblique and transverse), mineralogy, thickness, type of deformation it relates to, geometric style, laying elements, box lithology, shear ratio, alteration halos and layout elements. The qualitative analysis of the veins based on their geometric-kinematic relationship and the different deformational periods that affected the area points to the fact that the longitudinal veins may be associated with the low tectonic transport of P2 as well as the transverse veins and some of the oblique ones. The other two families of oblique veins were formed at the beginning of P4 or along this, associated with extrusive orogeny and final configuration of the area.

Abstract Aircraft operators often modify aircraft configurations, install new equipment, and alter airframes to accommodate this equipment, leading to operations in flight envelopes different from original design profile. These modifications necessitate airframe structural assessments, which typically require comprehensive aircraft design data, often unavailable to operators. This study aims to develop and validate a practical method for finite element analysis (FEA) of aircraft structures in the absence of this detailed design data. Focusing on a case study involving structural analysis of an aircraft wing, this study presents assumptions and idealizations used to develop 2.5D finite element (FE) model of the wing. Fidelity of this model is established by comparing FE analysis results with experimental data. Key validation metrics include reaction forces, load distribution at wing-fuselage attachments, and deformation at reference points on the wing under design load. Comparison between FE analysis and experimental results is carried out to substantiates accuracy of these geometric simplifications and idealizations of load-carrying behaviour of structural members. Therefore, practicality of these idealizations in absence of design data is demonstrated. This study offers a novel approach for structural assessments of aircraft without relying on proprietary design data. The validated method enhances capability of aircraft operators to perform effective structural analyses, thereby extending service life of aircraft with continued airworthiness

Resumen Los operadores de aeronaves a menudo modifican las configuraciones de las aeronaves, instalan nuevos equipos y modifican las estructuras de los aviones para acomodar estos equipos, lo que lleva a operaciones en envolventes de vuelo diferentes al perfil de diseño original. Estas modificaciones requieren evaluaciones estructurales de la estructura del avión, que normalmente requieren datos completos de diseño de la aeronave, que a menudo no están disponibles para los operadores. Este estudio tiene como objetivo desarrollar y validar un método práctico para el análisis de elementos finitos (FEA) de estructuras de aeronaves en ausencia de estos datos de diseño detallados. Centrándose en un estudio de caso que involucra el análisis estructural del ala de un avión, este estudio presenta suposiciones e idealizaciones utilizadas para desarrollar un modelo de elementos finitos (FE) 2.5D del ala. La fidelidad de este modelo se establece comparando los resultados del análisis FE con datos experimentales. Las métricas clave de validación incluyen fuerzas de reacción, distribución de carga en las uniones ala-fuselaje y deformación en puntos de referencia en el ala bajo carga de diseño. Se lleva a cabo una comparación entre el análisis EF y los resultados experimentales para corroborar la precisión de estas simplificaciones geométricas e idealizaciones del comportamiento de carga de los miembros estructurales. Por lo tanto, se demuestra la practicidad de estas idealizaciones en ausencia de datos de diseño. Este estudio ofrece un enfoque novedoso para evaluaciones estructurales de aeronaves sin depender de datos de diseño patentados. El método validado mejora la capacidad de los operadores de aeronaves para realizar análisis estructurales efectivos, extendiendo así la vida útil de las aeronaves con aeronavegabilidad continua.

Abstract The mototaxi, a three-wheeled vehicle equipped with a roof, is a widely utilized mode of transportation in Mexico. Typically, it is employed for short-distance journeys in exchange for payment, similar to the operation of a conventional taxi. This study conducts a structural analysis of a mototaxi-type vehicle utilized in Mexico to assess its performance and safety. It underscores the significance of this mode of transportation, widely relied upon by numerous individuals. A product design and development methodology was employed, utilizing torsional deformation simulations to validate the new geometry. The objective was to minimize torsions as much as possible, thereby enhancing the motorcycle taxi’s safety and ensuring the vehicle’s correct positioning. Through computeraided design, the prevailing torsions within the casing were assessed, establishing the operating conditions to which the system is commonlysubjected. The findings from the chosen vehicular structure reveal a flexural rigidity of 6,508.15 N/mm, torsional rigidity of 27.35 KNm/º, and a range of natural frequencies between 8-21 Hz. These values indicate favorable resistance against bending forces and operational frequency. However, the torsional results exhibit deficiencies, suggesting an unsafe structure for all motorcycle taxi occupants. Consequently, technology developers and national legislators should prioritize enhancing the structural integrity of such vehicles.

Resumen El mototaxi es un vehículo de tres ruedas y con techo que se usa como medio de transporte popular en México, generalmente para recorrer caminos cortos a cambio de dinero, de la misma forma que opera un taxi. Esta investigación presenta el análisis estructural de un vehículo tipo mototaxi empleado en México, para evaluar su desempeño y seguridad, teniendo en cuenta que es un medio de transporte utilizado por muchas personas. Se empleó una metodología de diseño y desarrollo de producto, utilizando simulaciones de deformación torsionales para validar la nueva geometría, minimizando las torsiones en lo posible, tratando de mejorar la seguridad del mototaxi, así como la posición correcta del vehículo. Mediante el diseño asistido por computadora se probaron las torsiones existentes en la carcasa, determinando las condiciones de operación por las que generalmente es sometido el sistema.Los resultados obtenidos en la estructura vehicular seleccionada son para la rigidez por flexión de 6508,15 N/mm, la rigidez torsional de 27,35 KNm/º y el rango de frecuencias naturales en 8-21 Hz, valores que muestran que la estructura presenta condiciones favorables mediante esfuerzos de resistencia por flexión y la frecuencia de operación de la estructura, pero carencias en los resultados torsionales, generando así una estructura insegura para los ocupantes del mototaxi. Es necesario que los desarrolladores de tecnología como los legisladores nacionales actúen en favor de mejorar sus condiciones estructurales.

Abstract For the understanding of the shear behavior of steel fiber reinforced concrete beams without stirrups (shear reinforcement), beams were experimentally studied employing bending tests. The analyzed parameters were two classes of compressive strength (30 MPa and 45 MPa) and three dosages of fibers (40 kg/m³, 60 kg/m³ and 80 kg/m³), in addition to the reference trace. An analytical comparison of the experimental results with calculation models from normative regulations and scientific papers was studied to predict the failure force of the beams. The results showed gains in the ultimate shear strength provided by steel fibers, evidencing their great potential against shear stress. The failure mode of the beams was not altered for the dosages of fibers and compressive strength classes studied. However, higher load and deformation capacity was evidenced with an increasing number of fibers and f c . The model from Brazilian regulation NBR 16935 (ABNT, 2021a) showed excellent results in predicting the failure force of the beams in group C30.

Resumo Para o entendimento do comportamento ao cisalhamento de vigas de concreto reforçadas com fibras de aço e sem a utilização de estribos, foram estudadas experimentalmente vigas por meio de ensaios de flexão. Os parâmetros analisados foram duas classes deresistência à compressão (30MPa e 45MPa) e três quantidades de fibras (40kg/m³, 60kg/m³ e 80kg/m³), além de um traço de referência. Uma comparação analítica dos resultados experimentais com modelos de cálculos de regulamentações normativas e de trabalhos científicos foi estudada para a previsão da força de ruína das vigas. Os resultados experimentais demonstraram ganhos na resistência última ao cisalhamento proporcionado pelas fibras de aço, evidenciando seu grande potencial frente ao esforço de cisalhamento. O modo de ruína das vigas não foi alterado para as quantidades de fibras e classes de resistência estudadas. Porém, maior capacidade de carga e de deformação foi evidenciada com o aumento da quantidade de fibras e do fck. O modelo da norma brasileira NBR 16935 (ABNT, 2021a) mostrou excelente resultado na previsão da força de ruína das vigas do grupo C30.

ABSTRACT The gold and silver deposits of the Vetas-California mining district are hosted in Paleozoic gneisses and Mesozoic granites of the Santander massif in the Eastern Cordillera of Colombia, far from the northern Andean volcanic arc. In the California area, there is ambiguity in defining the epithermal-type metallogenic model with high to intermediate sulfidation due to the presence of Late Triassic-Early Jurassic and Miocene magmatism. The best-known hydrothermal episodes comprise two early porphyritic-style phases: a) characterized by a propylitic alteration with molybdenite of the ∼10.1 Ma-old La Mascota breccia, related to granodiorite porphyries and smaller-volume rhyodacitic dykes; and b) attributed to a magmatic-hydrothermal system due to phyllic alteration associated with quartz-pyrite veins with hydrothermal sericite dated at ∼3.4 Ma. These two hydrothermal episodes were followed by four epithermal phases related to the development of multiphase hydrothermal breccias and quartz-alunite alteration, defined by bornite, covellite, and chalcopyrite, alongside wolframite, enargite, and sphalerite, with gold and silver mineralization between ∼2.6 and ∼ 1.6 Ma. To understand the relationship of the emplacement of the porphyries and the subsequent auro-argentiferous enrichments to the deformation front observed in the Pamplona buttress, to the east of the Santander Massif, a 4D structural model of the mineralization is formulated here. This model is based on the spatial analysis of the stresses responsible for the La Baja-Angostura dextral fault in terms of the regional kinematics of the Bucaramanga sinistral fault. It is considered that the SW sector of the deposit area corresponds to a well-defined, tabular, sub-vertical body of the La Mascota breccia. On the other hand, the NE sector in the La Baja-Angostura fault is expressed as a topographically elevated right horsetail splay, which controls the more disseminated distribution of the mineralization by means of veinlet swarms arranged in an ∼E-W direction. The disseminated mineralization of Vetas-California was probably favored by late thermal expansion-contraction events in the gneissic sockets, which allowed the accumulation and precipitation of boiling solutions rich in volatiles and elements of economic interest.

RESUMEN Los depósitos auroargentíferos del distrito minero Vetas-California están alojados en gneises paleozoicos y rocas ígneas mesozoicas del Macizo de Santander en la cordillera Oriental de Colombia, a cientos de kilómetros del volcanismo septentrional Norandino. En el área de California, existe ambigüedad en la definición del modelo metalogénico de tipo epitermal con sulfuración alta a intermedia debido a la presencia de magmatismo del Triásico tardío-Jurásico temprano y Mioceno. Los episodios hidrotermales mejor conocidos comprenden dos fases tempranas de estilo porfirítico: a) una caracterizada por una alteración propilítica con molibdenita de la Brecha La Mascota, de edad ∼10,1 Ma, relacionada con pórfidos de granodiorita y diques riodacíticos de menor volumen; b) otra atribuida a un sistema magmático-hidrotermal con alteración fílica asociada a filones y vetas de cuarzo-pirita con sericita hidrotermal de edad ∼3,4 Ma. A estos episodios le suceden cuatro fases de estilo epitermal relacionadas con el desarrollo de brechas hidrotermales multifásicas y con alteración de cuarzo-alunita, definidas por bornita, covelina y calcopirita, además de wolframita, enargita y esfalerita, con mineralización de oro y plata entre los ∼2,6 y ∼1,6 Ma. En la presente contribución se formula una hipótesis del modelo 4D del control estructural de las mineralizaciones para comprender la relación del emplazamiento de los pórfidos y los subsecuentes enriquecimientos auroargentíferos con respecto al frente de deformación reconocido en el Contrafuerte de Pamplona, al oriente del Macizo de Santander. Para ello, se analizan los esfuerzos responsables de la falla dextral La Baja-Angostura a partir de la cinemática regional de la falla sinistral de Bucaramanga. Se establece que el sector SO del área de mineralización corresponde a un cuerpo bien definido, tabular, subvertical, de la Brecha La Mascota. En el sector NE, en cambio, la Falla La Baja-Angostura se expresa como una cola de caballo (horsetail) derecha, topográficamente más elevada, la que controla la distribución diseminada de la mineralización mediante enjambres de vetillas subordinadas dispuestas en dirección principal ∼E-O. La mineralización diseminada de las Vetas-California fue favorecida probablemente por fenómenos tardíos de dilatación-contracción térmica de los encajantes gnéisicos, que permitieron la acumulación y precipitación de soluciones en ebullición ricas tanto en volátiles como en sustancias de interés económico.