Prestressing Force Research Articles

Study on Mechanical Response Characteristics of Anchor under Dynamic Disturbance

The roadway surrounding rock is often subjected to severe damage under dynamic loading at greater mining depths. To study the dynamic response of prestressed anchors, the damage characteristics of anchor solids with different prestresses and number of impacts under dynamic and static loads were investigated by improving the Hopkinson bar equipment. The effect of prestress on stress wave transmission was obtained, and the laws and reasons for axial force loss under static and dynamic loads were analyzed. The damage characteristics of anchor solids were determined experimentally. The results show that with an increase in prestress from 15 to 30 MPa, the peak value of the stress wave gradually increases and the decay rate gradually decreases. Shear damage occurred at the impact end of the specimen, combined tension and shear damage occurred at the free end, and fracture occurred in the middle. With an increase in the number of impacts, the damage to the anchor solid specimens gradually increased, and the prestressing force gradually decreased. After impact, the axial force of the various prestressed anchor solid specimens gradually increased; however, the anchor bar with a 17 MPa prestressing force had the slowest rate of axial force loss during impact, withstanding a greater number of impacts. In on-site applications, after three explosions, the displacement on both sides of the tunnel supported by 17 MPa prestressed anchor rods could be controlled within 0.3 m, with an average displacement of 206, 240, and 283 mm, respectively, increasing by 16.5% and 17.9%. This study, based on theoretical analysis and laboratory research combined with field application provides guidance for the anchor support of a dynamic loading tunnel.

Evaluation on structural performance of hybrid composite post-tension plate girder through finite element analysis

ABSTRACT Plate girders are typically formed by the built-up of I-shaped plates. It is vulnerable and weak in resisting buckling. In this study, FE analysis models were developed to evaluate the flexural performance of a hybrid composite post-tension (HCPt) plate girder. The HCPt plate girder is made of double-web and in-fill concrete with pre-stressed tendon to prevent shear web buckling and improve flexural resistance. The sensitivity of design parameters to the performance of the girder was also investigated through a parametric study using four different configurations. The selected parameters are span length, steel grade, concrete grade, and level of pre-stressed force. The statistical analysis was performed using linear multiple regression model to predict the girder’s flexural load and displacement. The results showed that web shear buckling was eliminated for models with in-fill concrete and pre-stressed tendon and failed by bending. Failure of the girder with double web was demonstrated by the combination of bending and web shear buckling. The concrete in-fill prevents the web plate from buckling and the beams generally fail in bending with high ductility. The load capacity of the hybrid composite plate girders with pre-stressing improved by 76% and 44% compared to conventional single-web plate girders and double-web plate girders, respectively.

Flexural performance of precast segmental continuous box girders with corrugated steel webs

Due to the existence of joints, the flexural performance of segmental assembled girders is different from that of monolithic cast girders. In order to study the flexural performance of precast segmental assembled box girder with corrugated steel webs, a static failure test on a precast segmental assembled continuous box girder with corrugated steel webs and variable cross-section and a monolithic cast continuous box girder with corrugated steel webs of the same size was carried out. The influence of the existence of joints on the deflection, strain, and prestress increment of precast segmental continuous girder with corrugated steel webs was analyzed. The parameter analysis was further carried out by the finite element method. The results showed that, at the initial loading stage, the joint had little effect on the displacement, and the deflection of the segmental assembled girder changed more rapidly than that of the monolithic cast girder. In the monolithic girder, cracks mainly occurred at the middle-support position of the middle span and pure bending sections. In the segmental beam, cracks were concentrated in the concrete on both sides of the joint. The number of cracks was relatively small and concentrated in the concrete on both sides of the joints of the loading segment and the middle support segment. The trends in the strain growth in the segmental beam and MB01 were consistent, and the values were similar. The strain growth trend of the segmental girder and the monolithic girder was consistent, and the values were similar at the initial loading stage. The external prestressed tendons in the segmental girder had a greater role in the loading process than those in the monolithic girder, and the normal stress in the segmental girder increased more rapidly during the bending process. In the ultimate loading state, the external prestressing force of the segmental girder was 2.01% higher than that of the monolithic girder. The number of segments was inversely proportional to the flexural capacity of the structure. Excessive thickness of the adhesive layer would adversely affect the crack resistance of the structure. This study will contribute to the engineering application of continuous composite box girders with corrugated steel webs.

Comprehensive Numerical Modeling of Prestressed Girder Bridges under Low-Velocity Impact

Accidental collisions involving over-height trucks that exceed vertical clearance limits and bridge superstructures frequently happen, resulting in compromised girders and potential threats to structural safety and performance. The numerical simulation of large-scale prestressed girder bridge collisions poses challenges due to the associated nonlinearities, as well as the limited availability of large-scale experimental testing data in the literature due to cost and complexity constraints. This study introduces a numerical modeling approach to efficiently capture the response of prestressed girder bridges under lateral impact loads. A finite element (FE) model was developed using LS-DYNA and meticulously validated against experimental data from the literature. The study explored four methods for applying prestressing forces and evaluated the performance of four concrete material constitutive models, including the Continuous Surface Cap Model (CSCM), Concrete Damage Plastic Model (CDPM), Karagozian & Case Concrete (KCC) model, and Winfrith concrete model, under impact loads. Furthermore, an impact study was conducted to investigate the influence of impact speed, impact mass, and prestressing force on the behavior of prestressed girder bridges. Utilizing the dynamic relaxation (DR) approach, the developed FE model precisely captured the response of prestressed girders under impact loads. The CSCM yielded the most accurate predictions of impact forces, with an error of less than 8%, and demonstrated a strong ability to predict damage patterns. Impact speed, mass, and the presence of prestressing force showed a significant influence on the resulting peak impact force experienced by the girder. Furthermore, the study underscores the composite nature of the bridge’s response and emphasizes the importance of analyzing the bridge as a whole rather than focusing solely on individual girders.

Post-earthquake fire resistance of self-centering concrete beam-column joint: An experimental investigation

Fire is an accidental disaster resulting in disastrous consequences for building. Post-earthquake fire is a secondary disaster induced by earthquake, triggering off larger destruction in a higher probability of occurrence. The potential severity of consequences to structures makes fire and post-earthquake fire safety imperative in the design of any new structures. Self-centering concrete joints are introduced as a promoting alternative to traditional reinforced concrete (RC) joints. They always exhibit excellent seismic performance and self-centering capacity, available in high-seismic zone. However, the current lack of experimental data on fire response of self-centering concrete joints means that they remain an open issue in current design codes. In this paper, full-scale quasi-static cyclic test and fire tests were conducted on two self-centering concrete joints connected with bolted angles and posttensioned (PT) tendons. The experiments aimed to explore the performance of self-centering joint in fire situations, and the impact of post-earthquake damages on fire response of self-centering joint. The deformation patterns and thermal responses of self-centering joints including temperature distribution, prestress force of PT tendons, displacements at beam ends and duration were recorded and analyzed. The results show that both self-centering joints exhibited satisfactory fire resistance with endurance over 170 min. Generally, the bolted angles and PT tendons in self-centering concrete joints showed acceptable working performance in fire. The findings unveil the actual response of self-centering concrete joints during the fire and post-earthquake fire conditions, providing experimental data for further numerical simulation and analysis. It can be used to calibrate the design approach for self-centering joints under fire and seismic-induced fire exposure.

Efficient Design Optimization of Cable-Stayed Bridges: A Two-Layer Framework with Surrogate-Model-Assisted Prediction of Optimum Cable Forces

Cable-stayed bridges have commonly been built for crossing large-span obstacles, such as rivers, valleys, and existing structures. Obtaining an optimum design for a cable-stayed bridge is challenging, due to the large number of design variables and design constraints that are typically nonlinear and usually conflict with each other. Therefore, it is a reasonable alternative to turn the large and complex optimization problem into two sub-problems, i.e., optimizing the internal force distribution by adjusting the cable prestressing forces, and optimizing the other sizing or geometrical parameters. However, conventional methods are lacking in efficiency when dealing with the problem of optimization of cable forces in the first sub-problem, under the circumstance that iteration between the two sub-problems is required. To address this, this paper presents a surrogate-model-assisted method to construct a cable forces predictor ahead of the structural optimization process, so that cable forces can be effectively predicted rather than optimized in each iterative round. Additionally, B-spline interpolation curve is adopted for variable condensation when sampling for the surrogate model. Finally, the structure optimization in the second sub-problem is performed by leveraging an optimization program based on particle swarm optimization method. The performance of the proposed framework is tested with a practical engineering application. Results show that the proposed method showcases good efficiency and accuracy. The theoretical raw material consumption of the towers and the cables is 32% lower than the original design.

Study on the Stresses Released in a Notched, Postensioned Concrete Beam

Structural prestressed concrete elements (SPCE) face uncertainties in accurately assessing the actual prestressing force. Over time, the initial prestressing force decreases due to several factors. Incorrect estimation of prestress losses can lead to design inefficiencies or structural issues. Monitoring the prestressing force can be achieved through instrumentation during casting, but existing SPCE lack such devices, necessitating indirect methods to determine prestressing force variations. This study focuses on analyzing stresses released in a notched post-tensioned concrete beam using the saw-cutting technique. Surface notches induce local decompression, allowing for strain measurements in the isolated concrete block. These measurements, considering uncertainties in initial prestress and material properties, are analyzed through backward calculations. The findings enhance understanding of saw-cutting and enable future applications to determine effective prestressing force in unmonitored SPCE. Further experimental studies are required to explore prestressing force consistency under monitored conditions. This research provides valuable insights into the potential of the saw-cutting technique as a non-destructive testing method for assessing prestressing force in unmonitored SPCE. Accurately determining the prestressing force is crucial for evaluating existing SPCE and ensuring their structural integrity. Keywords: prestressed concrete, beam, test, saw-cut, notch

A PZT active sensing method for monitoring prestressing force based on the ultrasonic reflection coefficient

Prestress monitoring is key to ensuring the safety and longevity of post-tensioned prestressed structures. A new method of prestress monitoring, based on piezoceramic transducers, is proposed. Compared to traditional ultrasonic detection, we utilize piezoelectric (PZT) active sensing monitoring, eliminating the need for a specialized ultrasonic probe. First, a relationship model between the signal received energy and loading force is established based on the principle of ultrasonic reflection coefficient at the contact interface. On this basis, we overcome the low signal-to-noise ratio issue associated with the traditional method by employing the time reversal (TR) method. Next, the model parameters were fitted using experimental data. The values of the fitting evaluation metrics, SSE and RMSE, tend to be close to 0, while the R-squared value tends to be close to 1. This indicates the reliability of the model. Finally, the prestressing force validation tests are conducted through unloading tests. The average relative error between the measured and actual values across different paths ranges from 6.85% at the minimum to 15.61% at the maximum. Since the method is related to the proximity of the interface contact, it can be applied in other areas of civil engineering, such as assessing the adhesive strength of composite structures, crack development, and detecting axial stress.

Influence of strand rupture on flexural behavior of reduced-scale prestressed concrete bridge girders with different prestressing levels

In prestressed concrete (PC) bridges, high-strength prestressing steel plays a key role in the flexural response of girders. In both pre-stressed and post-tensioned PC bridge girders, damage induced by corrosion or impact of under-passing high vehicles may led to rupture of one or more strands, significantly affecting the load-carrying capacity against dead and traffic loads. This paper presents an experimental study on the response of PC girders affected by strand rupture at different locations. Four reduced-scale post-tensioned concrete girders with different levels of initial prestressing force were tested under four-point bending. Two specimens with a different level of prestress were initially tested in undamaged configuration to provide a basis for the assessment of damage effects. The other pair of specimens were intentionally damaged - having the same initial prestressing level of their undamaged counterparts - in the lower tendon to investigate their limited flexural response under different performance levels including serviceability and collapse. Damage turned into a different critical cross section outside the loading region, i.e. both cracking and collapse were attained 1.1m away from midspan. In the last section of the paper, a cross sectional analysis of the girder was developed at cracking and ultimate conditions for the prediction of damage impact on failure mechanisms, thus validating the experimental findings.

Universal Bond Models of FRP Reinforcements Externally Bonded and Near-Surface Mounted to RC Elements in Bending.

The use of fibre-reinforced polymer materials (FRPs) for the retrofitting of reinforced concrete (RC) structures has become very popular. However, the main concern for the exploitation of FRPs is their premature debonding failure modes. This paper presents two different universal models for calculating flexed RC elements strengthened with externally bonded and near-surface mounted FRP reinforcements, which were derived by coupling principles of the fracture mechanics of solids and generally accepted assumptions. The first model allows a complete analysis of the behaviour, development, and propagation of rupture of the joint. The main advantages of the proposed model, compared to existing ones, are that it does not require additional bond shear tests to identify missing factors, and it is versatile and suitable for both externally bonded reinforcements (EBR) and near surface mounted (NSM) strengthening techniques. In addition, the concrete-FRP connection is divided into zones and the current phase and length of each zone are determined, allowing for more detailed analysis of the connection at different load stages. The proposed computational model and its derivation focus on the performance of the joint between the two cracks and the distribution of the shear stresses in that joint. The second one requires fewer computations and can be fully exploited when the joint is treated as a unit, without division. The results of the calculations have been validated using the experimental database of 77 RC beams and strengthened with externally bonded and near-surface mounted carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) sheets, plates, strips, and bars taken from 13 different studies. Both the prestress force and the initial stress state before strengthening were evaluated.

A PZT-Based Smart Anchor Washer for Monitoring Prestressing Force Based on the Wavelet Packet Analysis Method

Prestressed steel strands in prestressed structures offset or reduce the tensile stress caused by external loads, making them the primary load-bearing components. Great concerns have been raised about prestress monitoring due to the growing use of structural health monitoring (SHM). Piezoceramic (PZT) active sensing methods are commonly used in this field. However, there appears to be a problem of “energy saturation” in the utilization of piezoceramic active sensing methods. In this study, a smart anchor washer with semi-cylinders was developed to alleviate the saturation problem. An intelligent monitoring system is formed by combining the upper and lower annular cylinders with two piezoelectric patches. The piezoelectric patch on the upper annular cylinder is used as an actuator to emit signals through the contact interface of the smart anchor washer, which are then received by the piezoelectric patch on the lower annular cylinder. Based on wavelet packet decomposition, we investigate the correlation between the energy of the received signal and the applied tension force. Finally, a prestressing force index is developed for monitoring prestressing force using Shannon entropy. It is found that the index decreases with the increase in tension. The proposed design and index are also sensitive to early monitoring of prestressing force and can be used to monitor the entire prestressing process of steel strands.

Computationally-efficient high-fidelity nonlinear FEA of seismically isolated post-tensioned RC bridges

This study presents a novel computationally efficient high-fidelity nonlinear FEA (NLFEA) methodology for prestressed RC bridges constructed in the UAE and seismically isolated with elastomeric bearings. Specifically, the presented NLFEA methodology, using 3D solid brick elements, is shown to overcome traditional prohibitive numerical burdens. This is demonstrated without compromising accuracy or upscaling applicability and appropriateness. The proposed NLFEA approach is highlighted through detailed modeling of RC bridges’ non-traditional structural components and loading aspects (elastomeric bearings and post-tension prestressing cables). The mechanical behavior of elastomeric isolators and the RC continua, including cracking and other nonlinear phenomena, are captured via 3D solid brick elements. Moreover, the modeling procedure accurately represents the post-tension tendons’ prestressing forces and the associated effects on the RC elements. The prestressing forces are incorporated within the tendon elements via insightful manipulations of stepwise initial conditions and internal force adjustments. Additionally, load-carrying capacity determination for the elastomeric bearings was achieved by conducting a parametric investigation to capture their mechanical behavior adequately. Eventually, the analysis of a full-scale bridge is presented in this paper. The post-tensioned RC bridge understudy spans 100 m over eight elastomeric (natural rubber) seismic isolator bearings. Twelve post-tension prestressing cables are utilized to provide the bridge with continuous internal tension-balancing forces. A high-fidelity detailed FEA model of the complete bridge is developed and validated against a SAP2000 FEA model. It is shown that reasonable computational efforts can be expected without compromising the accuracy of the results.

Vibration reliability of steel beams prestressed by drawing

Introduction. Vibrations of building structures and mechanism parts were analyzed. The need to investigate the oscillation processes and vibration reliability of steel beams prestressed by web drawing was formulated. The subject of study is structural steel. The object of study is bimetallic steel beam prestressed without rods.Materials and methods. The scientific inquiry is based on the basics of structural mechanics of buildings and structures: superposition principle, differential equation of deflection curve of a bar, energy method, and methods of determination of stress-strain state of prestressed steel bars.Results. A comparative analysis of vibration reliability of non-prestressed beams and prestressed structures of equal bearing capacity was performed. Rotations of the beam supporting nodes loaded by prestressing forces and external impacts were determined by integration of differential equation of deflection curve of a split bar. The support moments in rigid supporting nodes of structures were determined on the basis of superposition principle. The developed methods of stressed condition of prestressed bars are the basis for determination of normal stresses in the sections of beams under study. The resultant stresses were obtained by algebraic addition of prestresses and stresses from external loads. Dynamic parameters of bearing capacity of beams were determined on the basis of works by I.M. Rabinovich and V.A. Kiselev. The oscillation circular frequency of conventional and prestressed beams was established, analytical expressions for determination of angular velocity of prestressed bending elements were formulated, and the dynamic deflections and factors of structures were determined. It is found that the circular frequency of prestressed beams hinged in supporting nodes compared to the circular frequency of conventional beams decreases by a factor of 1.4 and by a factor of 5.6 in beams with rigid supports. Angular velocity decreases by a factor of 1.4 (hinge supports) and 6.8 (rigid supports), respectively. The deflections of prestressed beams are reduced by a factor of 1,87: 11,9. There is a significant reduction in the stressed condition of prestressed structures.Conclusions. A hinged traditional beam under external and vibration loads in limit state is in the material yield zone and does not meet the first and second limit state conditions. These structures have the lowest vibration reliability. Prestressed structures are more reliable. With rigid supporting nodes, the moments of prestressing forces coincide with the supporting moments and produce hogging with the vector opposite to the external load deflection vector. In the limit state, total deflections are less than the external load deflections. Stresses in the structure decrease. Since load moments and beam deflections are initial parameters for dealing with dynamic strength tasks, we may state that prestressed beams with rigid supporting nodes have an increased vibration reliability.

Numerical and digital image correlation study of the flexural behavior of prestressed ultra-high-performance concrete beams made from locally available materials

This paper presents finite element simulations of the flexural behavior of three prestressed ultra-high-performance concrete (UHPC) beams based on the concrete damaged plasticity model (CDPM) available within Abaqus. A novel numerical model that applies the prestressing force through surface traction is proposed. The flexural deformation of the prestressed UHPC beams is simulated from the application of the prestressing force through failure under flexural loading. Material properties were measured and informed values for CDPM input parameters. The model was compared with four-point loading tests previously conducted to study the flexural behavior of large-scale prestressed UHPC beams. Digital image correlation (DIC), supplemented with traditional sensors, was used during the test to monitor behavior. The primary results based on the numerical modeling are as follows: • The model is validated to accurately simulate the flexural behavior of prestressed UHPC beams, both in global deflection and local strain. • The prestressing process, including camber deformations, is effectively simulated. • The new approach to apply prestressing force in the model can be applied in scenarios requiring large prestressing forces. • The numerical results are also validated through comparison with DIC results. The new numerical modeling approach will be effective for guiding experimental studies and design of prestressed UHPC beam elements.

Evaluation of the residual prestressing force in reinforced concrete elements by means of prestress release tests

Prestressed reinforced concrete elements can be subjected to relevant stress variations over time because of steel stress relaxation and concrete time- dependent deformation, often amplified in case of possible steel strands failure, caused by progressive material degradation. This will lead to a significant reduction of the overall prestressing force. The age of the majority of Italian bridges, originally designed without particular attention to durability, is quickly approaching their design service life. In this framework, the need to periodically evaluate the deterioration level of the materials becomes of paramount importance, in particular for prestressed steel strands; this will allow the attainment of a reliable estimation of the residual prestressing force in prestressed reinforced concrete beams (common in bridges and viaducts). The present paper aims at evaluating the reliability of a semi-destructive technique which can be used for performing prestress release tests on reinforced concrete elements by means of the removal of small portions of concrete, often involving only a portion of the concrete cover. Tests were performed on reinforced concrete columns subjected to a predefined compressive axial load, in order to have a direct comparison between the experimental deformation, measured by means of strain gauges, and the effective axial stress, applied through the experimental set-up. Different parameters have been considered during the tests, such as the geometric sawing configuration and the order of the steps performed before the removal of the concrete sample, evaluating their effect on the strain release, with the aim of proposing a reliable procedure easily applicable during in-situ tests.

Modelling of fire behavior of RC girders strengthened by external prestressing

Since the 1950s, external post-tensioning has been a powerful tool for retrofitting existing bridges. In unbonded prestressing, the post-tensioning tendons are positioned outside the concrete cross-section, and the prestressing forces are transferred to the girder through end anchorages, deviators, or saddles. This implies that these could be critical elements for the bridge performance against fire. This paper examines reinforced concrete bridges strengthened by external prestressing and subjected to fire, using a mixed experimental and analytical approach. Initially, load tests are conducted on a model of a bridge beam strengthened by external prestressing to assess the effectiveness of the intervention until failure. The ultimate limit state (ULS) capacity of the beam is then evaluated both before and after rehabilitation. Subsequently, the fire performance is investigated through different scenarios defined by the fire load curves of Eurocode, evaluating the cross-sectional temperatures resulting from fire, estimating the loss of external prestressing efficiency, and assessing the beam’s overall fire resistance. This methodology is then applied to a real girder bridge with adjacent beams of the same type, extending the approach used on the experimental scaled beam to an actual bridge deck. Results are presented in terms of performance levels for different traffic load values and residual capacity over time from fire ignition, providing a safety assessment of girder bridges under fire exposure. The procedure is straightforward and immediately applicable to many existing reinforced bridges. The findings demonstrate how quickly external prestressing degrades, leaving the beam unprotected, and highlight the fundamental importance of the protective sheath for external tendons in limiting this degradation. Evaluating load levels based on exposure time also allows engineers to estimate the service time before rescue arrives, given the expected traffic level.

Identification of pre-tensioning of rebars based on the acoustoelastic effect

Rebar as the core vertical prestressing stressing member of the bridge structure. The stress loss can not be effectively controlled during the whole process of anchorage, coupled with the influence of environmental corrosion. The result is that the vertical prestressing force cannot meet the design requirements, seriously threatening the durability and safety of the structure. This paper combines ultrasonic guided wave technology with acoustic elasticity theory to detect the effective prestressing of rebar. Guided wave propagation characteristics and acoustic elasticity effect under different tensile forces after bare rebar and outsourcing mortar are investigated. Tension tests and guided wave propagation tests were carried out on the specimens to analyze the variation rule between the first wave speed of guided waves and the tension force. The results show that the first wave speed of the guided wave decreases with the increase of the excitation frequency, which is consistent with the theoretical frequency dispersion curve. With the gradual increase of the excitation power, the amplitude of the guided waveform received by the rebar increases gradually only in the time and frequency domains. The law between first wave speed and tension after the outsourcing mortar is consistent with that of bare rebar. It is feasible to establish an identification method of prestressing rebar based on acoustoelastic effect.

Experimental and analytical investigation on the evaluation of residual stresses in prestressed concrete girders

Since the strength of prestressed reinforced concrete (PRC) structures, particularly under shear, substantially depends on the effective residual prestressing force, the evaluation of residual stresses in prestressed concrete structures is currently a target of importance. Three semi-destructive techniques were used on the 4 PRC full scale: core trepanning, saw-cut at intrados, and blunt pyramidal specimen for in-situ prestressing evaluation based on tension release. Furthermore, a novel method, resembling parallel saw cuts at the intrados but applied to the web, was introduced and examined. Among the tested techniques, this latter approach demonstrated the highest reliability, and both 2D and 3D finite element models were developed and extensively discussed to support the findings.

Resilient seismic performance of self-centering hybrid rocking reinforced concrete wall: Numerical simulation

A reinforced concrete rocking wall is engineered to endure seismic forces, leveraging its motion to absorb earthquake energy and mitigate collapse risks. In earthquake-prone regions, self-centering walls offer a durable solution, capable of returning to their original positions post-event. This study proposes an innovative Self-centering Hybrid Rocking Wall (SHRW) integrated with a replaceable Flexural Plate Energy Dissipator (FPED) to minimize concrete wall damage during earthquakes and streamline subsequent repairs. Utilizing the ABAQUS platform, a validated finite element model, based on experimental data, was developed to analyze the robustness of the proposed FPED-SHRW, focusing on the FPED’s energy-dissipating capacity. Additionally, a series of FPED-SHRW samples underwent cyclic loading assessment to investigate resilient performance, considering factors such as initial prestressing force, post-tensioned strand location, and flexural energy dissipator device thickness. The results demonstrate that the suggested self-centering hybrid rocking wall with a flexural plate energy dissipator exhibits exceptional resilient properties, including high energy dissipation capacity, effective self-centering ability, and superior strength and stiffness. This design achieves the objective of minimizing damage during earthquakes and expediting rehabilitation afterward. Furthermore, simulation outcomes confirm the sensibility of the numerical model based on ABAQUS.

Experimental and Analytical Studies of String Steel Structure for Bridges

Due to their efficiency, suspension structures are widely used in both roof slabs and different kinds of bridges, from which stress ribbon pedestrian bridges can be distinguished. The main disadvantage of the latter is high deformability, especially under asymmetrical loads. Recently, string structures or their systems have been introduced into bridge building. Numerical and experimental analysis of string behaviour under symmetrical and asymmetrical loads is carried out in the article. Analytical expressions for the calculation of string displacements and tensile forces are presented. The impact of the string pre-stress on the state of its stresses and deformations was evaluated. The assessment of the accuracy of analytical expressions by applying the results of numerical and experimental research is presented. A methodology is proposed for calculating the pre-stressing force taking into account the operational requirements. Three main loading options at different string pre-stress values are analysed. It is worth mentioning that the difference (error) between the analytical and numerical results is not extensive, it does not exceed 3%. It is necessary to notice that in all cases, the analytically obtained results are somewhat higher than FEM (numerically) obtained results.