Support Beam Research Articles

The Influence of Moment Redistribution on the Optimization of Beam Reinforcement in Multistorey Structures

The redistribution of design bending moments in continuous reinforced concrete beams is widely acknowledged as a valuable resource for designers of reinforced concrete structures. Moment redistribution is beneficial for practical design, as it provides flexibility in reinforcement arrangement. According to IS 13920:2016, the minimum reinforcement at the bottom face of the beam at support locations must be 50 Parsant of the top reinforcement at the same point. At the same time, it should be no less than 25 Parsant of the support reinforcement at midspan to meet ductility requirements. In detailing the junctions between columns and beams, the author has noted that congestion of reinforcement at the column faces of the beams poses practical challenges when placing both longitudinal and transverse rebars for the columns. This congestion can lead to inadequate concrete compaction, increasing the risk of honeycombing. By redistributing the top moment in the beam at the support location to the bottom face at midspan, it becomes possible to reduce both the top and bottom reinforcement at the supports, thus optimizing the reinforcement allocation in beams. This study examines a three-dimensional G Plus 20-storey building, which includes both laterally stiffened and unstiffened designs with symmetrical plans. The entire structure is situated in zone III on medium soil conditions, incorporating partial moment releases. The percentages of moment redistributed in the beams were determined at 10 Parsant, 20 Parsant, and 30 Parsant for the laterally unstiffened structure, and 10% for the laterally stiffened structure. Following this, a response spectrum analysis was performed using STAAD Pro. By IS 13920:2016, comparisons were made between the beams' top and bottom-face longitudinal reinforcement across various moment redistribution values.

Study of the modification mechanism and reinforcement performance of functionalized graphene-based structural adhesives

ABSTRACT This study investigates the effectiveness of modified graphene (MGE) for developing novel structural adhesives and their application in concrete beam reinforcement. The research aims to reveal the mechanism of MGE and evaluate the effect of different reinforcement methods on the flexural performance of concrete beams. Two adhesive formulations – original structural adhesive (OSA) and functionalized graphene-based structural adhesive (FGSA) – were examined alongside two reinforcement methods: the grouting reinforcement method and the adhesive fiber-reinforced polymer (FRP) method. The results show that the increased spacing of the functionalized MGE flakes improved their dispersion in epoxy resin, enhancing cohesive forces through bonding interactions and leading to the enhancement of the basic mechanical properties of FGSA by 6% to 12%. Compared to OSA, the application of FGSA improved the flexural properties of concrete beams, with the degree of improvement depending on the reinforcement method, while the failure mode of the beams remained unchanged. In addition, the FGSA/FRP combination showed the most significant improvement in the fracture parameters (220% to 480%) compared to the unreinforced control, highlighting its efficiency and cost-effectiveness as a reinforcement method. These findings offer valuable insights into reinforcement strategies for concrete beams, addressing the limitations of structural adhesive bond strength and optimizing reinforcement techniques.

Moment-curvature restoring force model of PVC-CFRP confined concrete column-RC ring beam joint

To accurately characterize the nonlinear mechanical behavior of polyvinyl chloride-carbon fiber reinforced polymer (PVC-CFRP) confined concrete column-reinforced concrete (RC) ring beam joints under low cyclic loading, 11 ring beam joints are designed based on the principle of “strong members and weak joints” and subsequently fabricated. Various parameters, including the ring beam reinforcement ratio, ring beam width, CFRP strip spacing, axial compression ratio, and frame beam reinforcement ratio, are considered. Generally, as the ring beam reinforcement ratio, ring beam width, axial compression ratio, and frame beam reinforcement ratio increased, the moment-curvature curves of the joint specimens demonstrated improved seismic performance. Subsequently, a simplified model of the moment-curvature skeleton curve is proposed based on the experimental results. Utilizing the simplified model, along with Clough tri-linear degradation model, the hysteretic behavior rules of the joints are formulated, the moment-curvature restoring force model is then developed to simulate the hysteretic behavior, which agrees well with the experimental data.

3D PRINTING TECHNOLOGY FOR MONOLITHIC BEAMS WITH THE POSSIBILITY OF REINFORCING BARS

The integration of 3D printing technology in construction has the potential to reduce costs and accelerate the construction and installation processes. While this technology is gaining global attention, Ukraine currently lacks regulations governing the design and construction of structures using 3D printing. Additionally, there is a limited experimental base regarding the bearing capacity and deformability of printed structures. This publication proposes a methodology for the production of monolithic beams reinforced with single bars using a construction 3D printer. It outlines the entire process of manufacturing, from the design phase to product fabrication and readiness for experimental research. To carry out the research, the design of the beams was first created using graphic software systems, which facilitated the formulation of tasks for a construction-grade 3D printer, considering the capabilities of this technology. Design and production drawings of the samples are included in this publication. The reinforced monolithic beams were printed using a construction 3D printer by the Ukrainian company 3D TECHNOLOGY UTU LLC, following the developed work algorithm. This methodology enabled the reinforcement of structures with single bars, in compliance with regulatory requirements, while allowing for future experiments. As a result of this work, reinforced monolithic beams were successfully printed using the developed technology. To assess the physical and mechanical characteristics of the materials, samples of cubes and prisms were printed and cast into formwork. Additionally, reinforcement samples were created from the same batch used to reinforce the beams. The proposed technology for producing beams with a 3D construction printer resulted in structures that adhered to previously established design solutions. The detailed sequence for printing beams allowed for effective reinforcement of monolithic beams with single bars.

Optimum design of reinforced concrete beam sections with JAYA algorithm

Section design is an important process for designing reinforced concrete structures because of the existence of factors such as bearing capacity and cost. After defining the initial cross sections for reinforced concrete elements, reinforcement amounts are calculated within the framework of certain rules and regulations. In the classical method, optimum cost and reliable structure can be designed by trial and error. Designing with the classical method is quite time-consuming. As in different fields, metaheuristic algorithms are employed to civil engineering applications to reach the optimum solution. In this study, unlike other examples from the literature, the optimum cost design of reinforced concrete beam cross-section was done, adding torsional moment to bending moment and effects of shearing force through the use of the JAYA algorithm. The optimum cost design of a reinforced concrete beam section under the effects of torsional moment, bending moment and shear force is performed. The design is done according to the rules specified in ACI 318 (Building code requirements for structural concrete), as it is well-known and used in many international projects. For the purpose of this study, cross-sections of 10 different reinforced concrete beam cross-sections were designed under 5 different loads for 2 different concrete classes through MATLAB software, with the aim of finding the optimum beam cross-section. A reinforced concrete beam is designed under different torsional loads and for different concrete classes and it is aimed to find the optimum beam cross-section. It shows the effect of torsional force on reinforced concrete beam cross section and reinforcement by using different torsional loads. It was observed that the algorithm used tends to approach the optimum result, increasing the area of concrete with lower unit cost or reducing the distance between stirrups. It was concluded that Jaya algorithm performs effectively with respect to optimizing reinforced concrete beams. The algorithm used can be applied to different reinforced concrete elements.

A failure mechanism seen after the 6th February 2023 Kahramanmara earthquake sequence, buckling of compression reinforcement in RC beams

A failure mechanism seen after the 6^th February 2023 Kahramanmara earthquake sequence, buckling of compression reinforcement in RC beams

Optimization of 3D-printed reinforced concrete beams with four types of reinforced patterns and different distances

The enhancement of mechanical properties in reinforced concrete beams remains a pivotal focus in modern structural engineering. In the pursuit of innovative solutions, recent studies have explored the potential of 3D-printing technology to reinforce cementitious materials. However, challenges persist in optimizing this approach. This study investigates the reinforcement of cement beams using four distinct 3D-printed patterns: Honeycomb, 3D-Honeycomb, Grid, and Triangle. Each pattern was strategically positioned at varying distances from the neutral axis to assess its impact on the beam’s flexural strength. The findings reveal that the Honeycomb pattern, when placed 10 mm from the bottom of the beam, enhanced flexural strength by over 25 %. The 3D-Honeycomb pattern, positioned at 5 mm, demonstrated similar improvements. Notably, the Grid pattern, also placed 5 mm from the bottom, resulted in a remarkable 46 % increase in flexural strength, while the Triangle pattern contributed to a 30 % enhancement. Further optimization was achieved by combining two reinforcement patterns. The Honeycomb pattern exhibited strain-hardening behavior and increased flexural strength by over 76 %. The 3D-Honeycomb and Grid patterns further augmented flexural strength by 76 % and 72 %, respectively. The most significant improvement was observed with the Grid pattern, which boosted flexural strength by more than 118 %. This study underscored the transformative potential of 3D-printed reinforcement in cement beams. The strategic use of Honeycomb, 3D-Honeycomb, Grid, and Triangle patterns not only enhances flexural strength but also induces strain-hardening behavior, leading to strength gains between 76 % and 118 % compared to the control sample. These findings offer valuable insights for the development of advanced construction materials and techniques.

Evaluation of the Performance of Concrete Reinforced with Bamboo and Incorporating Cassava Peel Ash

Introduction The main materials utilized in the production of reinforced concrete are aggregates, cement, and steel. The production of steel and cement contributes to the generation of carbon dioxide emissions, which is a main cause of global warming. Methods To further enhance sustainability in the construction industry, this study focuses on utilizing alternative sustainable materials in bamboo-reinforced concrete containing cassava peel ash (BRC-CPA) by fully replacing steel with bamboo strips and partially replacing cement with cassava peel ash. The experimental phase includes material characterization for the cassava peel ash (CPA) and bamboo reinforcements. Eighty-nine samples of BRC-CPA beams with dimensions 100×150×500 mm were produced, and bamboo strips of three different sizes, 12, 14, and 16 mm, were prepared and used as reinforcement in the BRC-CPA beams to evaluate their flexural strength and flexural strain. In addition, 12 samples of 150 mm cassava peel ash-blended concrete (CPAC) cubes without bamboo strips were produced. The cassava peel ash was used to partially replace cement at three levels, 0, 10, and 20%, to evaluate their influence on the compressive strength and water absorption of concrete cube samples. Results The addition of CPA slightly reduced the compressive strength of CPAC cubes, with values of 23.4 N/mm², 22.2 N/mm², and 21.4 N/mm² observed for 0%, 10%, and 20% CPA replacement levels, respectively. However, incorporating CPA had a positive effect by reducing water absorption and narrowing the flexural crack width in BRC-CPA beams. The flexural strength of BRC-CPA beams increased as the concrete aged, but decreased as the bamboo reinforcement size increased. Notably, at 20% CPA replacement, the flexural strength was less influenced by the bamboo strip size compared to beams with 0% CPA. Conclusion Based on experimental results obtained for compressive strength, flexural strength, and flexural crack width, cassava peel ash at 10% replacement and bamboo strips of size 14 mm were recommended for use in BRC-CPA for concrete structural elements such as beams, columns, and slabs.

Investigation on seismic behavior of a new beam-column joint for precast concrete structures under reversed cyclic loading

A new type of precast concrete beam-column connection based on partial steel-concrete composite structure is proposed to improve the seismic behavior and assembly efficiency of precast concrete structures. Quasi-static tests on half-scale models were initially conducted to assess the seismic behavior of the joint and the effect of the axial compression ratio. A refined finite element model of the joint was then created to explore the influence of various factors such as reinforcement ratio, strength of post-poured concrete, and yield force of the connecting plate on the seismic behavior. The experimental and analytical results show that including a steel joint connector in the core area creates local composite structures. These structures successfully redirect plastic hinges from the beam end towards a location closer to the mid-span, protecting the integrity of the core area concrete. As a result, the seismic behavior of the proposed joint exceeds that of traditional cast-in-place joints. Additionally, a higher axial compression ratio results in a fuller hysteresis curve for the assembled specimen, suggesting increased load-bearing capacity but reduced deformation capacity. Furthermore, increasing the beam reinforcement ratio or the strength of post-poured concrete improves the seismic behavior of the joint. The connection plate also plays a role in energy dissipation, and when its yield strength is about 1.2 times that of longitudinal reinforcement, the total hysteresis energy dissipation of the new joint increases by approximately 6.4 %. It crucial to ensure a high-quality connection between longitudinal reinforcements at beam ends and maintain proper pouring quality in practical engineering.

A Study on the Influence of Hydraulic Compactor Reinforcement on the Force Law of an Independent Foundation Under a Column and Its Safety Standard

Due to the complexity of the actual geotechnical environment, the backfill compaction design theory and calculation method are not reflected in the current specification. Therefore, in order to investigate the effect of the hydraulic compactor on the foundation structure during the treatment of the backfill of an independent foundation under a column, the Menard formula was modified. At the same time, relying on an independent foundation project under a column in Jinan, the dynamic model of compactor tamping backfilling soil was established. The applicability of the calculation formula is verified by simulating the single-point multiple tamping on the backfill directly above the foundation tie beam, and the influence law of two factors, the thickness of the backfill and the tamping energy, on the force of the foundation tie beam is elucidated. The results show that after reaching the optimum number of tamping, the cumulative soil settlement and the effective reinforcement depth of tamping show a stable trend, and their simulation results are in good agreement with the analytical solution, which provides a supplement to the relevant safety standards. At this critical point, the force on the tie beams peaked and showed up and down fluctuations under the subsequent ramming action. The tamping action of the compactor has a significant effect on the structural forces within the effective reinforcement range, and there is a negative correlation between the magnitude of the structural forces and the thickness of the backfill. According to the numerical calculation results to choose the best construction programme, the on-site monitoring shows that under 42 KJ tamping energy and 1.5 m single backfilling thickness, the tie beam reinforcement stress reaches 18.5~55.5% of the specification warning value, which meets the safety standard. The research results of this paper can provide important guidance for the hydraulic tamping treatment of an independent foundation backfill project.

Influence of web reinforcement on shear behavior and size effect of lightweight aggregate concrete deep beams: Experimental and theoretical studies

In practice, deep beams with web reinforcement are the predominant form of deep beams. Understanding the effect of web reinforcement in deep beams made of lightweight aggregate concrete (LWAC) is essential for the structural application of LWAC deep beams, but it is still a pending subject. In this study, eight LWAC deep beams and two normal weight concrete deep beams were tested to investigate the influence of web reinforcement and beam depth on the shear behavior and size effect of LWAC deep beams. The experimental results showed that all deep beams failed in shear–compression mode, which is independent of the web reinforcement ratio and beam depth. The web reinforcement confined the concrete within the strut area and limited the concrete spalling, which positively affected the normalized serviceability/ultimate shear strength. Moreover, web reinforcement effectively mitigated the size effect by resisting the transverse tensile stress and improving the boundary confinement of the concrete struts, but could not eliminate the size effect in LWAC deep beams. Based on these results, a modified strut-and-tie model (MSTM) was developed to quantify the contribution of web reinforcements to the shear capacity more accurately than the conventional strut-and-tie model. The predictions obtained using the MSTM with the Warwick-Foster’s strut efficiency factor were in excellent agreement with the experimental results.

Numerical evaluation of the performance of UHPC beams under bending and shear loads using different material models

The Microplane and Menetrey-Willam concrete models are formulated on the research work of Bazant and Gambarova and Menetrey-Willam in the nineties respectively. They are used in this thesis to predict how reinforced Ultra-High-Performance Concrete (UHPC) beams will behave when subjected to flexural and shear dominant loadings. The numerical models are available in ANSYS, and they can simulate UHPC's extraordinary mechanical properties, such as high compression and tension strength, strain hardening, and softening behavior in compression and tension. In this research, four UHPC beams with dimensions of 180 wide by 270 deep by 4000 mm long with tensile reinforcements were studied using the two cementitious composite models mentioned above with the ANSYS software. The beams were investigated under flexural four-point loading and shear three-point loading with the ANSYS program. A quarter-geometric section model of the full beam was considered for the four-point loading to take advantage of symmetry in the longitudinal and transverse directions of the beam. For the three-point loading, the full geometry model of the beam was considered only because of the lack of symmetry. The results from the ANSYS finite element software were validated with an experimental study conducted by different researchers to show its capacity to predict the bending and shear behavior of reinforced UHPC beams. The comparisons of the results of both material models show that they can simulate the behavior of UHPC beams by using experimental load-deflection plots of the beam specimens and force strain plots of the longitudinal tensile reinforcements in the sample beams.

Mechanics guided data-driven model for seismic shear strength of exterior beam-column joints

This study presents an enhanced predictive model for the seismic shear strength of exterior beam-column joints (BCJs). Initially, the principles of strut-and-tie mechanism and variable selection procedures were first utilized to identify the most influential parameters. Subsequently, an evolutionary algorithm, specifically multigene genetic programming (MGGP), was utilized to search for the near-optimal predictive model. The dataset used to develop, train, and test the proposed model was compiled from previously published tests, focusing specifically on cyclically loaded exterior BCJs that encountered shear and flexure -shear failures. The prediction performance of the developed model was assessed through various statistical measures, and then compared with that of other existing models. Additionally, sensitivity analyses were also performed to identify the influence and importance of each design parameter. The results demonstrated that the methodology employed in this study yielded an elegant model that adheres to the underlying mechanics and provides higher prediction accuracy compared to existing models. Furthermore, the sensitivity analyses showed that BCJ shear strength positively correlates with concrete compressive strength, beam reinforcement, joint transverse reinforcement, column intermediate vertical reinforcement, and axial load ratio, while it negatively correlates with the joint aspect ratio. Among these design parameters, beam reinforcement has the greatest influence on the model response, followed by concrete compressive strength. Conversely, column intermediate vertical reinforcement and axial load ratio have the least impact on the model response. The notable prediction capabilities and robustness demonstrated by the developed model render it an efficient design tool with promising potentials for adoption by practicing engineers and for consideration in design guidelines.

Shear Force of Interior Beam–Column Joints under Symmetrical Loading with Two Transverse Forces on the Beam

The beam-to-column connection is a particularly vulnerable element in frame structures under seismic action and is often responsible for building damages. Experimental investigations carried out over the past six decades on shear strength in frame joints have not led to the establishment of a uniform procedure in the design codes of different countries. The reason lies probably in the varied nature of the investigated parameters and in the varied configurations of beam–column connections. A good knowledge of the forces passing through the frame joints in the beam–beam and column–column direction would allow both their adequate computation in new buildings and the verification of existing ones without requiring experimental studies. In the design codes of the leading countries in seismic engineering, the shear force is determined by the capacitive method, considering only the area of the longitudinal reinforcement of the beam passing through the column. This method shows us how much shear force the beam reinforcement can take, but not what the magnitude of the resulting forces actually is as a result of the acting loads. In addition, the method of the codes does not indicate the contribution of the concrete to the total magnitude of the shear force in the beam–column connection. In the proposed mathematical model for calculating the forces that leave the beam, the full dimensions of the cross-section of the beam were taken into account. The material properties and cross-sectional shape were also taken into account. A determining factor for the magnitude of forces entering the beam–column joint is the acting load on the beam. In this paper, the load of two transverse forces was considered. The forces are applied in different possible positions, while remaining symmetrically located on the beam. The calculations are based on Menabrea’s theorem to determine the hyperstatic unknowns. The results of the proposed method for the considered beam show that the magnitude of the shear force differs from that accepted in the literature and the norms by 2% to 27%, depending on the stage of development of the crack. In comparison, the Eurocode-recommended method shows differences in the order of 27% to 40% for the adopted beam under static loads.

Flexural behavior of over-reinforced beam with ECC layer: Experimental and numerical simulation study

To optimize the brittle failure of reinforced conerete (RC) over-reinforeed beams and enhance their flexural performance, a novel structural form is proposed. To be specific, the Engineered Cementitious Composite (ECC) layer is installed on top of the RC over-reinforced beam (ERCOB). A total of six test beams are prepared, comprising one unreinforced beam and five reinforced beams. The variables comprised the depth of the ECC, reinforcement ratio, and whether the ECC is configured at the bottom. The test findings are subsequently compared with simulation outcomes to validate the model's precision. Next, the influence of various variables on ERCOB flexural performance, such as load-deflection response, bearing capacity, etc., is deeply analyzed. The research indicates that the ECC applied to both the top and bottom of the specimen exhibits enhanced bearing capacity and ductility. In comparison to CB-1, the maximum load and deflection ductility coefficient of EB-2 increased from 45.73 kN to 2.63–48.52 kN and 3.85, representing increases of 6.1 % and 29.6 %, respectively. It reveals that ECC layer improves the defects caused by excessive reinforcement of over-reinforced beams, and optimizes the tensile capacity of the steel bars, thus improving the bending capacity and ductility of the specimens. Finally, the prediction model of ERCOB flexural capacity is proposed to further verify the effectiveness of ERCOB. This study not only verifies the effectiveness of ECC reinforcement, but also helps to delay the failure process of structures, provide reference for future engineering application design.

Flexural Behaviour of Concrete Beams Reinforced With Major Steel Bars under Normal and Corrosive Operational Conditions

Quality assurance of construction materials is very fundamental for structural safety, reliability, serviceability, and durability of constructed civil infrastructure. Inflow of defective or substandard building and construction materials into the industry, particularly reinforcing steel bars, is responsible for many structurally deficient constructed facilities which often lead to failure or ultimate collapse of reinforced concrete (RC) structures. Characterization of steel rebars from two major manufacturers into Botswana construction industry, designated herein as M1 and M2, were conducted as a basis for the evaluation of the quality assurance and control of the products. The flexural behaviour of their respective RC beams, designated herein as B-M1 and B-M2, of dimension 150 × 200 × 3000 mm and subject to four-point loading tests were determined under normal and artificially induced corrosion conditions to assess the influence of steel rebars M1 and M2 on the stiffness and load-carrying capacity. The average yield strengths of steel reinforcing bars were 427 N/mm2 for M1 and 459 N/mm2 for M2. The moduli of elasticity for M1 and M2 were 203 GPa and 205 GPa, respectively. The percentage elongation was found to be 7.93% for M1 and 7.24% for M2. The flexural strength of beams reinforced with M1 was 7% and 16.5% lower than RC beam with M2 under normal and accelerated corrosion of 5% of NaCl solution for 60 hours condition, respectively. The flexural behaviour of RC beams reinforced with B-M1 had a lower flexural strength under both normal and corrosive environmental conditions as compared to B-M2. The flexural strength of B-M1 had reduced from 48.5 N/mm2 to 41.0 N/mm2, while B-M2 reduced from 52.2 N/mm2 to 49.2 N/mm2. This represented loss of load-carrying capacity of 15.4% and 5.8% for B-M1 and B-M2 respectively due to exposure to corrosive environment. The findings revealed disparity in bending capacity due to the low interfacial bonding due to reduced relative rib areas. A more intensive quality control of imported steel should be ensured at the ports of entry by relevant regulatory agencies.

Fracture Behavior of Crack-Damaged Concrete Beams Reinforced with Ultra-High-Performance Concrete Layers

Reinforcing crack-damaged concrete structures with ultra-high-performance concrete (UHPC) proves to be more time-, labor-, and cost-efficient than demolishing and rebuilding under the dual-carbon strategy. In this study, the extended finite element method (XFEM) in ABAQUS was first employed to develop a numerical model of UHPC-reinforced single-notched concrete (U+SNC) beams, analyze their crack extension behavior, and obtain the parameters necessary for calculating fracture toughness. Subsequently, the fracture toughness and instability toughness of U+SNC were calculated using the improved double K fracture criterion. The effects of varying crack height ratios (a/h) of SNC, layer thicknesses (d) of UHPC reinforcement, and fiber contents in UHPC (VSF) on the fracture properties of U+SNC beams were comprehensively investigated. The results indicate that (1) the UHPC reinforcement layer significantly enhances the load-carrying capacity and crack resistance of the U+SNC beams. Crack extension in the reinforced beams occurs more slowly than in the unreinforced beams; |(2) the fracture performance of the U+BNC beams increases exponentially with d. Considering both the reinforcement effect benefit and beam deadweight, the optimal cost-effective performance is achieved when d is 20 mm; (3) with constant d, increasing a/h favors the reinforcement effect of UHPC on the beams; (4) as VSF increases, the crack extension stage in the U+BNC beam becomes more gradual, with higher toughness and flexural properties; therefore, the best mechanical properties are achieved at a VSF of 3%.

Design of a Six-Story Teaching Building: A Comprehensive Approach to Safety and Structural Efficiency

This paper describes teaching building design. The project, designed for the teaching building, prioritizes safety in its main structure, a reinforced concrete frame with six floors above ground. The story heights are 4.2m, 3.9m, 3.9m, 3.9m, 3.9m and 3.9m, respectively, and the building's total height is 27.6m. The construction site category is classified as type II, and the first group's seismic fortification intensity is 7 degrees. The process includes architectural design, structural design, and PKPM checking calculation. Architectural design mainly consists of a general description. The plan, elevation, section, and draft of the corresponding building are drawn according to the relevant information and requirements provided by the design task book. Structural design mainly includes load statistics, calculation of internal force and displacement of the frame, a combination of internal force, and calculation of staircase, slab roof, floor slab and frame structure. The calculation of displacement, internal force, and reinforcement of the whole frame structure is carried. Out using PKPM. In the course of architectural design, safety is a paramount consideration, in line with the principles of safety, applicability, beauty, economy, and energy-saving requirements, referring to national standards and relevant materials, and strictly following the requirements of relevant architectural design standards, the design of each link is not only a comprehensive scientific consideration of its own but also a related discussion with teachers, as detailed in the construction plan. The frame structure is adopted,in this structural type. It mainly includes structure layout and calculation sketch determination, load calculation, internal force calculation, internal force combination, main beam section design, and reinforcement calculation, frame column section design and reinforcement calculation, secondary beam section design and reinforcement calculation, floor and roof design, staircase design etc. Among them, the D-value method is used to calculate the internal force of the structure under horizontal load, and the distribution method is used to calculate the internal force of the structure under vertical load (dead load and live load).

Seismic behavior and resilience assessment of prefabricated beam–column joint with replaceable graded-yielding energy-dissipating connectors

Conventionally assembled monolithic concrete frame structures achieve structural ductility through beam-end failure, which results in structures that are difficult to repair after an earthquake. To improve the seismic and resilience performance, a prefabricated concrete beam–column joint with replaceable graded-yielding energy-dissipating connectors (RGECs) is introduced. The connectors assembled on the upper and lower sides of the beam end dissipate energy and transfer the beam-end load with the steel hinge device. By adjusting the design bearing-capacity coefficient of RGECs to precast beams, the plasticity and damage of the structure can be centered on the core energy-dissipation bending–shear components (BSCs) and buckling segment (BS) of the RGEC, and the structural function can be quickly recovered by replacing only the damaged RGECs after a seismic disaster. Moreover, compared to the conventional joints, the joint with RGEC can achieve target seismic-performance goals at different seismic-risk levels by designing BSCs and BS with graded yielding. Low-cyclic-loading tests were performed on seven full-scale beam–column joint specimens to investigate the effects of different core energy-dissipating member thicknesses, beam reinforcement ratios and loading protocols on the seismic behavior of the proposed joint. Subsequently, the damaged RGECs were replaced, and the structural-function resilience performance was evaluated in terms of the function-recovery efficiency and quality, indicated by the hysteresis response, strain development, and component energy dissipation. The experimental results proved that the beam–column joint exhibited excellent seismic performance and could realize graded-yielding energy dissipation. The damage to the specimens was concentrated in the RGECs, the key members (beams and columns) were in an elastic state, and the energy dissipation ratio of the RGEC was more than 97 %. This enables the rapid recovery of function after earthquakes. After replacing the RGEC, the hysteresis response, strain development, and component energy dissipation of the specimens were consistent with those of the initial specimens. Compared with the original specimen, the difference in each seismic index of the replaced specimen was less than 10 %. Additionally, the structural function recovered quickly, and the resilient performance was good.

Pre-relaxed cables for improving progressive collapse resistance of RC frame subassemblages considering slabs

A common method to improve the progressive collapse resistance of reinforced concrete (RC) frame structures is to increase the reinforcements in beams, which might result in the undesired failure mode of strong beam-weak column for the structures under earthquakes. To improve the progressive collapse resistance of the RC frame structures without affecting their seismic behaviors, a novel retrofit has been proposed using pre-relaxed cables. This study investigated the improvement of the pre-relaxed cables on the progressive collapse resistance of the RC frame structures considering the presence of the slabs subjected to the distributed loads. A quasi-static test was carried out on two one-quarter scaled 2 × 2-bay subassemblages, i.e., a beam-slab (BS) subassemblage and a beam-slab-cable (BS-cable) subassemblage. Experimental results found that the progressive collapse resistance and deformation capacity of the BS-cable subassemblage was 55 % and 260 % larger than those of the BS subassemblage, respectively. The resistance improvement mechanism of the BS-cable subassemblages was revealed, i.e., the tensile catenary action in the beams, tensile membrane action in the slabs, and tension action in the cables. The finite element (FE) models were then developed, validated against the experimental results, and used for parametric studies with the consideration of the cable diameter and cable original length. Numerical results found that there were two failure modes for the BS-cable subassemblages, i.e., beam failure mode and slab failure mode. The upper limit of the improvement of the progressive collapse resistance using the cables is critically related to the failure mode. For the beam failure mode, the increase in the cable diameter could improve the progressive collapse resistance until the slab failure mode occurred.