Beams In Buildings Research Articles

Perspectives on the generalized modeling of six beam theories: A unified dynamic stiffness matrix

High-precision, efficient and streamlined methods for the dynamic modeling and analyzing of engineering structures have consistently captured attention of designers and researchers. This paper addressed this increasing demand by presenting a generalized modeling and analyzing method. Specially, a unified model was proposed to integrate six beam theories into a single formula. Upon this model, a unified dynamic stiffness matrix was derived, serving as an elemental building block for formulating the transfer matrix, frequency-dependent mass and stiffness matrices as well as further integrating finite element method, dynamic stiffness matrix method and transfer matrix method. Through this transition, challenges associated with transcendental eigenvalue in dynamic stiffness matrix method and transfer matrix method was effectively resolved and the advantages of transfer matrix method in handling complex structure were maximized. Given the widespread utilization of curved beams in buildings, bridges, robotics and sensors, the proposed method was validated through comparative analysis with other methods, focusing on both curved and straight beams. Furthermore, this study delineated applicability scopes of different beam theories and provided the strategic approach for curved and straight beams. The feasibility of this strategy was demonstrated through an investigation involving a corrugated structure comprising both straight and curved beams.

Optimizing bending strength of laminated bamboo using confined bamboo with softwoods

Abstract The objective of the study was to improve the stiffness and bending strength of laminated bamboo through confinement with softwood. A total of 144 beams were tested, divided into 6 groups of 24 specimens each. The tests were conducted on specimens of laminated bamboo, wood, and composite sections with different levels of confined bamboo laminate (20, 40, 60, and 80%). The results indicated that the composite exhibited optimal behavior when the ratio of bamboo to wood was between 46 and 54%. Furthermore, the composite demonstrated a bending modulus of elasticity that was 16.6% higher and a modulus of rupture that was 18.3% higher than the values predicted by the mixing rule. A mathematical model was developed to predict the design mechanical properties based on composite thickness. This model was validated through 18 additional bending tests. This new material is an environmentally sustainable alternative that has the potential to be used as beams in buildings, providing improved mechanical performance, reduced weight, and lower manufacturing cost compared to bamboo laminates.

Mechanical Performance of Puzzle-Shaped Shear Connectors Subjected to Fully Reversed Cyclic Stress

Recent innovations in composite dowels have led to the realization that robust hybrid systems can provide excellent strength and stiffness. In this contemporary era, puzzle-shaped and modified clothoid-shaped shear connectors are attracting interest, particularly in Europe. Their popularity stems from their outstanding shear capacities and their ease of manufacturing by virtue of having a single cutting line. Moreover, earlier studies based on pushout tests have proven this fact. Composite beams in buildings experience fully reversed cyclic stress between compression and tension during seismic events. When the concrete slab starts to crack under tensile stress, the shear capacity of the composite dowel can deteriorate considerably. Nevertheless, the influence of this cyclically applied stress on mechanical performance remains unclear. This study specifically examined puzzle-shaped shear connectors, with cyclic loading tests conducted using a component model of the composite beam, which can carry the various stress histories to the concrete slab. In all, findings obtained from 14 specimens with several influential factors clarified the cyclic behaviors and stress transfer mechanisms of puzzle-shaped shear connectors. Based on the experimentally obtained results, the applicability of existing evaluation equations was investigated with respect to the ultimate shear strength and shear force–slip displacement relation. Results indicate that those formulas overestimate the mechanical capacities of composite dowels under fully reversed cyclic stress. For that reason, this study has led to an evaluation formulation of mechanical performance that reflects the stress history effects. Ultimately, this study has proven that the proposed equations can assess the ultimate shear strength and shear force–slip displacement accurately while embracing simplicity.

Comparison between Manual and Software Approach towards Analysis and Design of a Residential Building

Abstract: In this study, the analysis and design of a G+2 residential building located at Guwahati, seismic zone V of India, has been done using STAADPro software and the results obtained are compared with manual analysis and design calculations. STAADPro software is used to analyze and design the building's beams, columns, and slabs (structural components). The limit state approach is used in the analysis, and the structure's members are designed in accordance with IS:456-2000 requirements. The loads and load combinations for design are based on IS:456-2000, while seismic forces are based on IS:1893-2002. Vertical loads on supports, as well as responses (deflection, axial force, shear force, and bending moment) for column and beam members, are compared using both software and manual calculations. Finally, the conclusion based on the comparison of the STAAD Pro result values and the manual design result values.

Risk assessment method of gas explosion based on quantification of margins and uncertainties (QMU):a case study on beam structures in buildings

Combustible gas explosions are common accidents in residential areas. Key building structural components, such as beams, slabs and columns, can be quickly damaged and destroyed by explosive overpressure loads, which may also result in continual collapse. Risk of interior gas explosions in buildings should be assessed to analyze the ability of structures to withstand disasters, which can also offer a theoretical basis for improving the structural design and construction of buildings. In this study, reinforced concrete beams in buildings were selected as the research object, and the risks to beam structures under mixed methane and air explosions were assessed using the quantification of margins and uncertainties (QMU) method. First, the uncertainty of the existing methods to calculate gas explosion and beam bending loads was analyzed. Through an influence regularity analysis, the expansion factor of combustible gas combustion products in enclosed explosion chamber, the initial density of the gas mixture in the explosion chamber before deflagration, the compressive strength of concrete, and the tensile strength of reinforcement were selected as the key uncertainty parameters. Furthermore, the Monte Carlo method was used to create 5000 samples of the selected uncertainty parameters, and statistical analysis was conducted to obtain the probability distribution of the gas explosion overpressure load and reinforced concrete beam bending load. Based on the sampling results, the beam structure’s safety margin and uncertainty analysis were analyzed to determine the probability of structural failure at the 90% confidence level. Finally, this paper provides guidelines for determining structural failure under different boundary value conditions of combustion explosion overpressure loads and reveals the sensitivity of different uncertainty parameters to structural safety margins using stepwise regression analysis. Compared to previous methods, this work includes the uncertainty features of disasters and disaster-bearing items when analyzing combustible gas explosion accidents; we anticipate it offers a fresh perspective on the quantitative assessment of gas explosion risks in buildings.

Spectroscopic Investigation of a Color Painting on an Ancient Wooden Architecture from the Taiping Heavenly Kingdom Prince Dai’s Mansion in Jiangsu, China

This research sheds light on the analysis of pigments and adhesives applied on a color painting on wooden architecture in Taiping Heavenly Kingdom Prince Dai’s mansion, located in Changzhou, Jiangsu Province in China. Four samples were collected from the painting above the building beam in the mansion, and the samples were analyzed and identified using a series of techniques, including polarized light microscopy (PLM), scanning electron microscope coupled with an energy-dispersive X-ray spectroscopy (SEM-EDS), micro-Raman spectroscopy (m-RS) and Fourier-transform infrared spectroscopy (FTIR). The results indicate that the red, black, blue, and green pigments were identified to be cinnabar, ivory black, indigo, and phthalocyanine green, respectively. The green pigment was inferred to be a lately repainted pigment based on its production age, suggesting that this ancient building had been refurbished or repaired. Given the good stability and visual effect of this green pigment, it is suggested to be used in future conservation processes. The pyrolysis-gas chromatography/mass Spectrometry (Py-Gc/Ms) results indicate that glue containing protein was used as a binder for the pigment samples, and that walnut oil might have been applied to the wooden architecture as a primer before painting. Our findings can well inform curators and conservators of the selection of appropriate restoration materials if necessary, and also provide data support for conservation of similar ancient buildings in southern China.

EXPERIMENTAL AND NUMMERICAL INVESTIGATION OF THE FRICTION BASED DEMOUNTABLE SHEAR CONNECTOR

AbstractIn order to provide sustainable structural solution for the steel‐concrete downstand composite beams in buildings by providing modularity and reusability, new demountable shear connector device based on frictional behaviour is devised. The mechanical behaviour of the newly developed connector is investigated both experimentally and numerically and its applicability in aforementioned application is assessed.

Study of the features of the work of concrete-steel composite beams in buildings with a steel frame

Concrete-steel composite structures are unique structures that combine the advantages of both steel and concrete. Their application is especially relevant in cases where construction objects need to withstand high loads with small cross-sectional dimensions. Thanks to the factory production of most of the elements and easy installation, it is possible to significantly reduce construction times. The main areas of application are high-rise construction, industrial construction, and bridge construction. The main task in the design of concrete-steel composite structures is to take into account the joint work of a reinforced concrete slab and steel beams, i.e. correct modeling of the structure when using calculation systems. This article explores various options for setting the numerical model of a concrete-steel composite beams using the example of one floor of a high-rise building, evaluates their reliability and compliance with the actual behavior of the structure. In conclusion, recommendations are offered on the numerical modeling of concrete-steel composite beams for calculation using the finite element method.

Evaluation of progressive collapse behavior in reinforced concrete buildings

Progressive collapse is a catastrophic chain reaction of failure of a structure that is caused due to loss of vertical load bearing element of the structure, resulting damage of a part of the structure or entire structure. In our research work 10 storey regular Reinforced Concrete framed structure is considered and is seismically designed with IS 1893:2016 in SAP2000 version 20 modeling. The different column removal scenarios both in plan and elevation suggested by guidelines were examined by alternate load path method using nonlinear staged construction available in the software and then identify the potential of the structure to withstand progressive collapse. Numerical results were compared by analyzing columns and beams separately by calculating demand capacity ratios and the requirement of percentage of steel for failed structural elements are predicted both in flexure and shear stresses. Our objective is to provide clear conceptual step-by-step descriptions of various procedures for progressive collapse analysis 3D (three-dimensional) Finite Element Methods (FEM) and non-linear static push-down analysis in SAP2000 software was used to assess the progressive collapse potential of a typical gravity-load designed mid-rise reinforced concrete building with open ground floor. The beam is actually designed to resist the shear force up to 39.84 kN. So in order to resist the shear failure we need to provide enough vertical reinforcement. The failed structural elements were re-designed to resist progressive collapse in order to satisfy the acceptance criteria recommended by the guidelines. It’s showed that the incorporation of perimeter beams in buildings improved the progressive collapse resistance as it reduces joint displacement and chord rotation at column removal locations by providing sufficient stiffness and load paths for increased gravity loads. The study results can be used to develop and calibrate the nonlinear numerical model for analyzing high-rise building progressive collapse behavior and can help provide information that may improve new and existing reinforced concrete core-wall building robustness against progressive collapse.

Bending Behaviour of Different Types of Timber I-Joist

Engineered wood I-joist is a structural system that comprises of flanges and web elements, and utilised as beams in buildings. Both elements must work together as a structural system to fit and meet the strength behaviour of a solid wood beam. The main objective of the study was to determine the bending strength behaviour of I-joist which produced from three types of jointed technique (finger, L-butt and nail plate) of oriented strand board (OSB) web element with two types of flange element (Keruing solid wood and laminated veneer lumber (LVL)). A total of 18 specimens of I-joist were tested to determine the bending behaviour, especially the modulus of elasticity (E) and modulus of rupture (MR). From the result of testing, LVL flanges specimen were obtained almost as strong as the specimens with solid wood flanges. Additionally, either solid wood or LVL flange was shown non-significant variances in bending strength behaviour because the MR values of the I-joist were insignificantly affected by flange element material. The I-joist specimen with finger jointed web was observed to be the strongest specimen when compared with other joints. Furthermore, the weakest joint among the three types of joints were fabricated with nail plate jointed web. The failures mode of the I-joist specimens were observed to fail due to tension or compression.

Hybrid Model of Machine Learning Refractory Data Prediction Based on IoT Smart Cities

With the advent of the digital age in recent years, the application of artificial intelligence in urban Internet of Things (IoT) systems has become increasingly important. The concept of smart cities has gradually formed, and smart firefighting under the smart city system has also become important. The method of machine learning is now applied in various fields, but seldom to the data prediction of smart firefighting. Various types of applications including data applications of machine learning algorithms in smart firefighting have yet to be explored. In this article, we propose using machine learning algorithms to predict building fire-resistance data, aiming to provide more theoretical and technical support for IoT smart cities. This article adopts the fire-resistance data of building beam components in a real fire environment, using three integrated machine learning algorithms, Extreme random Tree (ET), AdaBoost, and Gradient Boosting Machine (GBM), and the grey wolf optimization algorithm to optimize. We improve the grey wolf algorithm and combine the grey wolf algorithm with the machine learning model. The algorithm constitutes three machine learning hybrid models: GWO-ET, GWO-AdaBoost, and GWO-GBM. Compared with traditional grid tuning, particle swarm optimization (PSO), and genetic algorithm (GA) optimization, the robustness and accuracy of the three optimization algorithms and the machine learning hybrid algorithm on the data set are compared and analyzed. Performance is measured through various performance comparisons and experimental result comparisons. For various building beam component data sets under real fires, the optimization and comparison show that the mean square error (MSE) of the proposed algorithm is extremely small. The results indicate that the GWO machine learning hybrid model is superior to other models and has a smaller prediction error.

Efficiency of Hybrid Algorithms for Estimating the Shear Strength of Deep Reinforced Concrete Beams

Earthquakes occurred in recent years have highlighted the need to examine the strength of reinforced concrete (RC) members. RC beams are one of the elements of reinforced concrete structures. Due to the dramatic increase in the population and the number of medium/high-rise buildings, in recent years, the beams of buildings have been mainly designed and executed in the type of deep beams. In this study, the artificial neural network (ANN) with optimization algorithms, including particle swarm optimization (PSO), Archimedes optimization algorithm (AOA), and sparrow search algorithm (SSA), are used to determine the shear strength of reinforced concrete deep (RCD) beams. 271 samples from experimental tests are employed to develop algorithms. The results of this study, design codes equations, and previous research are compared. Comparison between the results shows that the PSO-ANN algorithm is more accurate than previous methods. Finally, SHApley Additive exPlanations (SHAP) method is utilized to explain the predictions. SHAP reveals that the beam span and the ratio of the beam span to beam depth have the highest impact in predicting shear strength.

Calculation of the improved steel beams of buildings and structures of the mining and metallurgical complex

Load-bearing elements of buildings and structures of the mining and metallurgical complex in recent decades need to develop new more effective design solutions due to the intensification of technological processes, an increase in temperature loads and aggressiveness of the environment. The main direction of increasing the efficiency of such elements is their design from economically alloyed steel, which allows to increase the resource of structures and prevent accidents with a significant increase in temperature. Due to the fact that alloyed steels have higher mechanical characteristics at elevated temperatures, the question arises of creating lightweight beam structures from such steels, reducing their material consumption while maintaining the stability and fatigue strength of beams, the most promising is the use of welded beams with a perforated wall and composite beams.
 The creation of the most effective cross-sectional shape of metal beams with a perforated wall and welded beams, as well as crane beams in transverse bending, considering strength, local stability, flat bending stability and fatigue strength is considered. It is shown that an effective shape of beams with a perforated wall is a box-shaped structure made of perforated channels. A calculation was carried out to select a rational design made of an assortment of hot-rolled channel profiles. It is shown that due to the use of the proposed sectional shape, significant savings in the weight of the structure can be achieved. Considering the three-dimensional stress-strain state, the fatigue strength of welded metal crane girders operating in severe conditions is estimated. The efficiency of using a hot-rolled I-beam as the upper chord of such welded beams is shown. The necessity of using a hot-rolled I-beam and to ensure the fatigue strength of the lower chord is demonstrated.
 The use of the previously proposed combined method for calculating the structures of industrial buildings and structures and the use of economically alloyed steels allows us to create new designs of critical elements that reduce their material consumption and increase their resource. Further research can be carried out for real object designs in order to reduce their cost and increase reliability during operation in the conditions of mining and metallurgical production.

Strengthening Prestressed Concrete Bridge Girders and Building Beams with Carbon Fiber Reinforced Polymer Sheets

The effect of Carbon Fiber Reinforced Polymer (CFRP) retrofitting and concrete type on the flexural strength of prestressed concrete I-section girders used in bridges and beams in buildings is investigated. Non-linear moment-curvature relationships are predicted using an iterative algorithm for both non-retrofitted and CFRP-retrofitted prestressed concrete girder and beam cross-sections with various concrete types. Two different CFRP-retrofitting schemes are analyzed for comparing their effectiveness. It is found that although non-retrofitted beam section exhibits greater ductility, the use of CFRP retrofitting in both tension and compression regions simultaneously results in a significant increase in flexural strength. It is also found that the higher the ultimate concrete strength, the higher is the influence of CFRP-retrofitting on increasing flexural strength.

Strengthening Prestressed Concrete Bridge Girders and Building Beams with Carbon Fiber Reinforced Polymer Sheets

The effect of Carbon Fiber Reinforced Polymer (CFRP) retrofitting and concrete type on the flexural strength of prestressed concrete I-section girders used in bridges and beams in buildings is investigated. Non-linear moment-curvature relationships are predicted using an iterative algorithm for both non-retrofitted and CFRP-retrofitted prestressed concrete girder and beam cross-sections with various concrete types. Two different CFRP-retrofitting schemes are analyzed for comparing their effectiveness. It is found that although non-retrofitted beam section exhibits greater ductility, the use of CFRP retrofitting in both tension and compression regions simultaneously results in a significant increase in flexural strength. It is also found that the higher the ultimate concrete strength, the higher is the influence of CFRP-retrofitting on increasing flexural strength.

Local deformation and strength characteristics of S-shaped reinforcement in wood

Reinforced wooden beam structures under the influence of critical loads are subject to brittle fracture, which is dangerous when operating beams in buildings. To solve this problem, reinforcement of wooden beams for civil and industrial buildings was invented using steel rope as a reinforcing element. The rope is located in the stretched area of the beams along the original S-shaped trajectory. Numerical studies of the deformation of the reinforcement model using the LIRA program are performed. Based on numerical studies, samples were made for testing for pulling S-shaped anchoring elements from solid wood. The analysis of deformation - strength characteristics based on the results of tests on a tensile testing machine glued curved rods. A triple increase in the ductility of the deformation of the paste in the zone of destructive loads was revealed. The main problems of this type of reinforcement are the appearance of stress concentrators in areas with a small radius of curvature of the reinforcement. As a result of the study, the optimal trajectory of the reinforcement insert was determined with the aim of obtaining higher strength and deformation characteristics - with a reduced oscillation amplitude. The possibility of using structures in the form of safety elements has been established, which allows to increase the destruction time of beam systems when exceeding the permissible load.

Non-linear finite element analysis of reinforced concrete deep beam with web opening

The use of Reinforced Concrete (RC) deep beams in building may requires web openings or holes for electrical and mechanical utilities passage. This web opening will change the behavior of RC deep beam and may resulted in early cracks even at service load. Hence, it is important to use a suitable tool to predict the full response of RC deep beam with opening. For that purpose, nonlinear finite element method using 3D-NLFEA software package which utilize a plasticity-fracture model is used to predict the behavior of RC deep beam. One deep beam specimen available in the literature is investigated. To study the effect of using structured and unstructured mesh, as well as different element types on the load deflection curve, hexahedral and tetrahedral solid element was used. From the comparisons, it was observed that the crack pattern between two different meshes was not similar. Structured mesh often has straighter crack propagation compared to the unstructured mesh. The load deflection curve for both models are similar and both models were performed satisfactorily in predicting the peak load of the deep beam.

Research on the Construction Characteristics of Stone-Built Folk Houses in Jiarong Tibetan Area <br/>—Take the Stone-Built Houses in Xisuo Village as an Example

The Jiarong Tibetan traditional residence is a characteristic regional architecture, located in a high-intensity, high-altitude and cold area, with geographic identification, and is a typical representative of this ethnic group. It has also become an important tourist destination and has important research value. The research used the methods of field survey surveying and mapping to conduct field survey and surveying on 20 buildings in Xisuo Village, a traditional village in the Jiarong Tibetan area. Measure building plans, elevations, and building sections, and collect measurement data for statistical analysis. The results show that the average total height of the building is 10.08 m, the average total building span is 12.44 m, the average total depth is 10.87 m, and the squareness is 0.87. The square shape of the building is more in line with the seismic requirements of high-intensity areas and the local terrain environment. The maximum window-wall ratio in the building is 0.18 south for the second floor, and 0.025 west for the first floor. Smaller window-to- wall ratios have better adaptability to high-altitude cold areas. The height of the building beam section is generally from 0.17 m to 0.32 m, and the average Beam span-depth ratio is 0.10. The building space construction has a good match with the properties of wood materials. These conclusions quantitatively analyze the characteristics of stone-built houses in high-intensity, high-altitude and cold areas, supplement the research on ethnic regional architecture, and provide materials and references for the design, repair and update of related buildings.

Push-out tests on three innovative shear connectors for composite cold-formed steel concrete beams

The composite action between concrete and steel makes the use of composite beams in buildings more economical than the use of typical hot-rolled steel beams. This can be attributed to the beam’s lower depth, which significantly reduces the weight of steel. Composite beams can be constructed by lipped C-channels made from cold-formed steel, concrete, and different shear connectors (which exhibit behaviours that are not yet well understood). In this study, the behaviour of three innovative shear connectors used in composite cold-formed steel concrete beams made of lipped C-channels with profiled metal decking was experimentally examined. Experimental tests aimed to determine the maximum resistance of the proposed shear connectors; these results were then compared with the predicted values and the values for other shear connectors investigated in other studies. Likewise, the ductility and the strength capacity of the shear connectors were investigated. Twelve push-out test specimens were prepared and tested in accordance with Eurocode 4. It was found that a shear connector’s strength capacity considerably depends on its deformation and on the crushing of concrete. The ductile behaviour of all the tested shear connectors satisfied the ductility requirements of Eurocode 4. In this study, it is concluded that the proposed shear connectors were suitable for use in the construction of composite beams, as they were stronger than the standard headed studs and the other available shear connectors; they were also sufficiently strong to perform composite actions.

Numerical Analysis for Reinforced Concrete Beams with Circular Openings in Flexural and Shear Zones Strengthened by Steel Plates

In the modern building construction, openings in beams are necessary to accommodate several service pipes and ducts. Due to these openings, high stress concentration occurs at its edges. Local cracks also appear around the openings as a result of the reduction in the beam stiffness, the load carrying capacity and the shear capacity. There are many studies which were conducted to develop and test different strengthening methods for the beams opining to increase the ultimate load capacity of the beams. However, from a practical point of view, it is better to have one strengthening method having the same specifications to be used in both; shear and flexural zones for circular opining beams in buildings. In spite of the prior studies, no study has addressed this issue; therefore, there is a need to study such a case. In this paper, an analytical study was conducted to investigate the behavior of the reinforced concrete (RC) beams with circular openings in flexural and shear zones strengthened by steel plates. A 3D FE modeling (ABAQUS 6.12) software was used to simulate five different specimens of RC beams. The study results showed that when the openings were strengthened by steel plates, the ultimate load carrying capacity increased, but the deflection was decreased when compared to the openings without strengthening. In addition, the model reliability was verified via good agreements between the experimental and numerical results.