Hollow Slab Research Articles

Research on the Application of Impact Echo Method in the Detection of Grouting Compactness of Hollow Slabs in Bridges

Research on the Application of Impact Echo Method in the Detection of Grouting Compactness of Hollow Slabs in Bridges

Structural Behaviour of Biaxial Hollow Slab and its Application in Construction Industry

Structural Behaviour of Biaxial Hollow Slab and its Application in Construction Industry

Damage identification of hinge joint in hollow slab bridge based on model updating and orthogonal matching pursuit algorithm

Hinge joints are crucial for transverse force transfer in prestressed hollow slab bridges. Damages to hinge joints cause overall instability, load distribution changes, and reduced bearing capacity of the bridge. A new method using model updating and the orthogonal matching pursuit (OMP) algorithm is proposed to accurately assess the damage of hinge joints in such bridges using a single measurement point. The hinge joint damage index obtained by the OMP algorithm is assigned to the corresponding hinge joint in the FE model to complete the model update. Results show that this method can accurately identify hinge joint damage locations and degrees with a single measurement point. The damage identification of 12 hinge joints of an in-service hollow slab bridge is carried out, and the findings reveal that the damage occurred on the fourth, fifth, and seventh hinge joints.

Flexural behavior of the hollow slab girders strengthened with ultra-high performance concrete: Field full-scale experiment and analysis

Due to high strength and well durability, ultra-high performance concrete (UHPC) can be designed to strengthen damage hollow slab girder. The main objective of this study is to evaluate reinforcement feasibility of compression zone of hollow slab girder via field full-scale experiments and finite element (FE) analysis. To this end, UHPC layer was firstly proposed to reinforce top plate of damaged hollow slab girder. Then, four-point bending tests were conducted to investigate flexural behavior of hollow slab girder with/without UHPC layer. FE models were developed to simulate bending failure process of hollow slab girders. The deflection, crack propagation and stress distribution of hollow slab girders were analyzed as well as failure modes. The results show that UHPC layers can significantly improve flexural stiffness of hollow slab girder, and it results in an increase of 11.5% in cracking load and 23.7% in ultimate load, respectively. Moreover, reinforced girder exhibits well ductility and relatively high flexural bearing capacity. Furthermore, the parameter analyses were performed to investigate the effects of the thickness of UHPC layer and prestress on flexural behavior of reinforced girder. The results show that the prestress significantly affects the ductility and cracking load. Whereas, it seems to be independence of ultimate load. Finally, theoretical analysis was performed to obtain calculation formulas, which determine cracking and ultimate loads of reinforced hollow slab girder. Overall, this study has verified effectiveness of proposed reinforcement method in improving stiffness and flexural bearing capacity of hollow slab girder.

A study on the deflection and crack layout in a hollow slab bridge

A study on the deflection and crack layout in a hollow slab bridge

Multifractal characteristics of fatigue cracks in the full-scale reinforced concrete hollow-slab beams

Highway Reinforced concrete (RC) bridges bear the repeated vehicle loads for a long time, promoting cracks' sprouting and development. Establishing a quantitative evolution model of cracks will improve the management and maintenance of similar bridges. Therefore, this paper introduces the multifractal theory into crack characterization and carries out the study on the multifractal characteristics of fatigue cracks in full-scale RC hollow slabs. Firstly, the basic procedure of the multifractal analysis method for concrete cracks is introduced, and the sensitivity of the multifractal spectrum under different influencing factors is analyzed. Secondly, the basic information and scheme of the experimental beam are introduced. The experimental results and the development law of fatigue cracks are analyzed. Finally, the variation law of the multifractal spectrum with cycle number is analyzed based on the multifractal theory, and a simplified evolution model of fractal dimension (FD) under fatigue load is established based on the experimental results. The experimental results prove that the multifractal theory is effective in describing the cracking state of RC members under fatigue load. The fatigue cracks' development of the experimental beam presents an obvious three-stage pattern: rapid stage, stable stage, and destabilized stage. The FDs of fatigue cracks also develop in a three-stage pattern along with cycle number, which can be expressed by a linear equation of cycle percentage. The evolution model can provide technical support for the maintenance decisions of RC bridges in service.

Experimental study on real bridge before and after simple-supporting to continuous reinforced concrete hollow slab

This article studies a concrete hollow slab simply supported-continuous actual engineering project in a certain city. Before the reinforcement of the bridge, there were cracks and exposed rebars, etc. In order to ensure the safe operation of the bridge, a reinforcement method of simply supported-continuous was adopted, prestressed steel strands are used to convert the simple-supported structure into a continuous structure, thereby improving the structural load-bearing capacity and overall integrity. Through conducting comparative analysis of load tests on a bridge before and after reinforcement, this article studies the improvement effect of the simply-supported-to-continuous reinforcement method on the bearing capacity of the bridge. A finite element model of the bridge was established, and comparative analysis was carried out before and after the reinforcement of the bridge. The bearing capacity and work performance of the bridge structure were evaluated. The research shows that the simply supported-continuous reinforcement method has a good improvement effect on the load-bearing capacity of the concrete hollow slab and can be used to improve the insufficient load-bearing capacity of the concrete hollow slab bridge in the city.

Investigation and comparison of numerical methods in predicting the behavior of rebar in reinforced concrete hollow slab (from start to crack) in Abaqus finite element software

Nowadays, the use of reinforced concrete hollow slab system in building structures is widely accepted due to the provision of control criteria, the ability to be used in large openings and flexibility in architectural designs, and it is more responsive in terms of economic efficiency and time management. has it. The use of reinforced concrete hollow slabs is one of the effective methods in styling and reducing the dead load and consequently the earthquake load, and as a result achieving sections with smaller dimensions. The aim of the current research is to study the post-cracking behavior of reinforced concrete hollow slabs under Common loading situations and analyzed using the finite element method. Also, by using the obtained results and comparing them with the behavior of laboratory samples, it is intended to determine the optimal numerical model for predicting the behavior of reinforced concrete hollow slab, and to measure the accuracy of common design relationships. Modeling of hollow concrete slab sample in this study has been done using ABAQUS software, and the results of this study showed; The load coincident with the first crack in the CDP method was obtained for 10.18, 15.2, 34.20, and 44 for the concentrated joint, concentrated grip, wide joint, and wide grip modes, respectively.

Experimental study and numerical simulation on the transverse force transmission mechanism of discretely connected precast RC floor

An innovative discretely connected precast RC floor (DCPCF) is presented, in which precast flat slabs (solid slab, sandwich slab or hollow slab) and spandrel beams (walls) are the basic components that connected by distributed mechanical connectors. The experimental program consisting six full-scaled DCPCF specimens and two cast-in-situ slab (CIS) specimens were conducted to evaluate the influence of slab joint structure on force transmission mechanism of DCPCF in orthogonal slab laying direction (OSLD), which in terms of the failure mode, deflection, strain development, etc. The results revealed that the slab joint connectors of DCPCF had good force transmission performance in OSLD, which can effectively transmit the flexural moment and connect the adjacent precast slab. Compared with CIS specimens, DCPCF specimens had no obvious plastic stage and entered elastoplastic stage earlier. The deflection of DCPCF in OSLD was mainly caused by the opening deformation of the slab joint and the rotational deformation of the precast slabs. For DCPCF specimens, the more connectors in each slab joints or the fewer slab joints, the greater the flexure stiffness in OSLD. Based on the test results, finite element models (FEMs) were developed to simulate force transmission mechanism of DCPCF in OSLD, and the accuracy was confirmed by the test results. Finally, it was verified that increasing the number of anchor bars and increasing the diameter of diagonal anchor bars can effectively enhance the anchoring measures of slab joint connectors to achieve replaceability of perforated steel plates.

A theoretical analysis method of transverse modal shapes of hollow slab bridge with hinge joint damage

Damage identification method based on modal shape change can be used to detect hinge joint damage of hollow slab bridges. However, in general, the modal shapes are usually obtained by identifying experimental data or finite element simulation, but the theoretical mechanism between hinge joint damage and the modal shape change is rarely investigated. In this paper, the influence of damage on modal shape is explored from the structural level, and an analytical transverse modal shape calculation method for the hollow slab bridge with hinge joint damage based on equivalent orthotropic plate is proposed. The analytical relationship between hinge joint damage and transverse modal shapes is obtained by equivalent hinge joint to elastic boundary condition. The finite element model of a hollow slab bridge is compared and verified with this method. The comparison results demonstrate that the analytical solution of the modal shape of hollow slab bridge with hinge joint damage can be precisely obtained by the proposed method, and the analytical transverse modal shape of hollow slab bridge with different crack heights coincide with the ones of the finite element solution.

Study on Mechanical Behavior of Hollow-Core Slab Bridge with Pinned Reinforcement.

Joints connect prefabricated hollow-core slabs, the key elements of force transmission of hollow-core slab bridges. The joints are easily damaged, which affects the integrity and safety of the hollow-core slab bridge. This paper uses MIDAS FEA NX finite element analysis software to simulate the deep hinge joint segment model, comparing and analyzing the finite element simulation analysis results with the test results, and proposes the critical parameters of the hinge joint interface and concrete damage plasticity. Further, an assembled hollow slab bridge model is established to compare and analyze the force transfer performance of conventional and pinned reinforcement bridges and reveal the deep joint damage evolution process. The results showed that the hollow slab bridge damage appeared first at the hinge joint interface at the load location. Cracks in the joints can develop along the longitudinal and height directions, with the longitudinal crack length reaching 40% of the span. The vertical crack height can get the lower edge of the paving layer, increasing the distance from the load position, and the cracking height decreases symmetrically. Under an ultimate load, the hinge concrete of conventional reinforcement and pinned reinforcement hollow-core slab bridges showed significant damage in 30-70% and 40-60% of the span, respectively. Compared with the conventional reinforcement bridges, the cracking load and ultimate load of the pinned reinforcement bridges increase by 28.57% and 58.14%, respectively, and the relative deflection under 420 kN load reduces by 97.95%. The hollow slab bridges have improved the force performance and thus enhanced the integrity of the hollow-core slab bridges.

Reduced area approach for predicting punching shear resistance of biaxial hollow slabs with openings

Due to the inclusion of hollow plastic spheres in bubbled slab systems, the shear resistance is greatly reduced. Also, the existence of the opening in the vicinity of columns takes away part of the concrete responsible for resisting shear forces and unbalanced moments, which in turn further reduces the punching shear capacity of the slab-column connection. In this study, experimental and theoretical investigations had been carried out on bubbled slabs with 2000 × 2000 × 230 mm dimensions. The investigated parameters were the size, position, distance of opening relative to the column stub, and the location of bubbles relative to the critical shear perimeter. A new calculation approach for determining punching shear resistance for bubbled slabs was developed. The proposed modification for calculating the effective critical perimeter showed an appropriate range of agreement of the punching shear strength, which is calculated by the methods adopted by (ACI 318, Eurocode 2, BS 8110, and AS 3600) codes, in comparison to the experimental data. The average ratios of the test results to the calculated punching shear capacity determined according to the proposed approach are between 1.007 and 1.417 with a standard deviation of 0.039–0.186 and a coefficient of variation of 0.038–0.131.

Study on propagation mechanism and attenuation law of acoustic emission waves for damage of prestressed steel strands

The study of acoustic emission waves propagation mechanism and attenuation laws for damage of prestressed steel strands is the theoretical basis for acoustic emission health monitoring of prestressed steel strands such as stay cables, slings, suspenders, and concrete structures. Firstly, the propagation mechanism of acoustic emission waves in prestressed steel strands is studied using numerical simulation methods. Secondly, the amplitude and energy attenuation laws of acoustic emission waves caused by damage of prestressed steel strands are analyzed by experimental research, and the amplitude and energy attenuation models of the influence of prestress level are constructed. Finally, the constructed acoustic emission attenuation models are analyzed in combination with practical engineering. The results show that numerical simulation visualizes the propagation path of acoustic emission waves in prestressed steel strands; With the increase of prestress levels, the acoustic emission frequency distribution of prestressed steel strands damage ranges from 100 to 200 kHz, with a dominant frequency of 160 kHz, the acoustic emission amplitude and energy attenuation coefficients decrease, and the amplitude attenuation is slower than the energy attenuation; The acoustic emission amplitude attenuation of prestressed steel strands damage in prestressed hollow slab beams is 5 times faster than that of steel strands without surrounding media.

Effect of strand debonding on the shear strength of existing pretensioned PC hollow slab

Pretensioned PC (prestressed concrete) beams experience strand debonding failure at the ultimate loading stage, which leads to bond-loss failure of the beams. To study the effect of strand debonding on the shear strength of pretensioned PC hollow slabs, the existing PC hollow slabs of 19 specimens with spans of 10, 13, 16 and 20 m used in Chinese expressway bridges were loaded to bond-loss failure. The strand slip, bond- loss failure mode and shear strength of 19 specimens and 31 shear tests were analyzed. The test results showed that the angles of the failure diagonal cracks were not consistent with the Ross model. Therefore, a refined model to predict the shear strength subjected to pretensioned PC hollow slabs was developed. Other factors were also considered in the refined shear strength model, including the dowel action of longitudinal reinforcements, the prestressed strand development length and the compression zone height. Compared with the shear failure controlled by strand yielding, the shear strength controlled by strand debonding was decreased by approximately 27 %. The test results showed that the debonding induced bond-loss failure could be described as follows: after the formation of the failure diagonal crack, the strand will clearly slip, and concrete parts on both sides of the failure diagonal crack rotate around the crack tip. Due to the debonding induced bond-loss failure of the pretensioned PC hollow slab, the shear strength could not be improved even by increasing the concrete strength of the compression zone. Finally, the validity of the refined model was verified by 23 test specimens.

Hinge Joints Performance Assessment of a PC Hollow Slab Bridge Based on Impact Vibration Testing

Hinge joint performance during the operation of prefabricated prestressed concrete (PC) hollow slab bridges is critical to ensure their lateral collaborative working condition and safe serviceability. Traditional performance identification of hinge joints mainly relies on manual inspection, which is inefficient and inaccurate. At the same time, existing indexes (such as acceleration and strain) can only qualitatively detect the damage to hinge joints. This study proposes a novelty detection method based on impact vibration testing to rapidly perform the quantitative assessment of the working condition of the hinge joints. The relationship between hinge joint performance and lateral load distribution (LLD) is first derived in detail by theoretical analysis. And then, the quantitative analysis of collaborative performance is converted to the identification of the LLD influence line, which is innovatively established by the lateral flexibility of the hollow slab bridge. The effectiveness of the proposed method is verified through a multibeam model using ABAQUS software, and the lateral collaborative working relationship between slabs is simulated using the connector elements. Furthermore, the LLD influence lines and hinge joints performance of a PC hollow slab Yanhu Bridge are evaluated based on the impact vibration testing with sensor lateral arrangement strategy. The detection results show that the proposed method can quickly and accurately identify the damage location and the stiffness loss of hinge joints.

Transverse Connectivity and Durability Evaluation of Hollow Slab Bridges Using Surface Damage and Neural Networks: Field Test Investigation

Prefabricated concrete hollow slab bridges are widely used in short- and medium-span highway bridges in China due to the advantages of high production quality, installation convenience, and low construction cost. Field investigation shows that severe hinge joint damage occurred during the service life, and mechanical performance of the bridges also deteriorated with the weakened joints. It is important to accurately evaluate the performance of hollow slab bridges to ensure the safety of the highway system. In this paper, transverse connectivity and durability of the concrete hollow slab bridges are investigated in a field test using the surface damage and neural networks. Hollow slab bridges in the Wu-He highway system were taken as the background bridge. Surface damage was visually checked and statistically analyzed. Static load test was conducted to evaluate the transverse connectivity of the hinge joints based on the girder responses. The hollow slab bridges were then demolished, and a total of 75 concrete girder segments were cut off. Durability of the girders was evaluated based on the conditions of concrete and rebars, and the analytic hierarchy process along with the fuzzy comprehensive evaluation method was employed. Results showed that there were two main types of the defects in the hollow slab bridges, i.e., the transverse cracks on the bottom plates of the girders and the longitudinal cracks in the hinge joints. The distribution of the deflection of each girder was non-uniform due to the weakening of the transverse connectivity, and the girders in the background bridges were within the moderate deterioration condition after 25 years’ service life. An evaluation method of the hollow slab girders using the neural networks and surface damage was verified by the field test data. The maximum crack width at different locations of the bridges was used in the input layer of the neural network, and the hinge joint damage or the durability was considered as the output results. The prediction error of the method in the test set was within 15.0% for the hinge joint damage and within 40% for the durability result of the girder, indicating the feasibility of the evaluation method.

Evaluation and Reinforcement of Prestressed Concrete Hollow Slab Bridge after Fire Damage

The bearing capacity of bridges after fire cannot be clearly defined, and the bearing capacity of bridges after fire cannot be evaluated by actual bridge load tests. In order to solve this problem, this paper studies the actual bearing capacity and reinforcement methods of hollow slab bridges after fire, combined with practical engineering cases. During the operation period of 16m span prestressed concrete hollow slab after fire detection, the bearing capacity is calculated according to the appearance, rebound strength, carbonization depth of the fire zone of the hollow slab and pier, as well as the compressive strength of coring, the tensile strength of steel, the natural frequency of vibration, dynamic strain and deflection of the hollow slab; The research results show that the bearing capacity of bridges after fire calculated by this method is more accurate, and the reinforcement scheme is formulated according to the calculated bearing capacity, which has achieved good results after reinforcement. It providing a reference for the detection and reinforcement of similar bridge diseases.

Seismic Performance Comparison of Simply Supported Hollow Slab on Pile Group Structure with Different Operational Category and Shear Panel Damper Application

This study is aimed to compare the seismic performance of simply supported hollow slab on pile group (SHSPG) structures designed as “critical” and “essential” viaducts with shear panel damper (SPD) devices. There were three numerical models to be compared, namely SHSPG-A, SHSPG-B, and SHSPG-C. SHSPG-A is a “critical” viaduct with 35 piles per one pile head. SHSPG-B is an “essential” viaduct with 18 piles per one pile head. SHSPG-C is an “essential” viaduct with 18 piles per one pile head plus sixteen SPDs. Numerical models considered the prestressing effect of the spun pile. Nonlinear time history analyses were executed using seven pairs of recorded ground motions that had been scaled and adjusted to the seismic characteristics of Yogyakarta, Indonesia. As the result, the performance level of SHSPG-A was much better than SHSPG-B. The SPDs application could maintain SHSPG-C’s performance at the same level as SHSPG-A and dissipate 34.28%-53.03% of the seismic energy.

Study on Lateral Distribution Coefficients of Hollow Slab Bridges After Reinforced by Pasted Steel Plates

This paper adopts a new method of pasting steel plate to restore the transverse connection of hollow slab bridge, so that the strengthened bridge can meet the requirements under the state of serviceability. The original beam of the concrete hollow slab with a span of 8m from the Suizhong to Shenyang section of Jing-Shen highway was reinforced by a method of pasting steel plates. In the test the eccentric load condition was loaded and the abaqus software was used for numerical calculation after the reinforcement. Based on the theory of load transverse distribution coefficient of bridge structure, different calculation methods were used to obtain the transverse load distribution coefficient of the strengthened test beam, and it is verified that the hinged plate method can be used to calculate the hollow slab beam strengthened with steel plate. In addition, combined with previous calculations, test results and numerical analysis, this paper discusses the restoration effect of the new type of pasted steel plate reinforcement method on the bridge lateral connection. The results show that the hinged plate method can be used to calculate the load lateral distribution coefficient of hollow slab beams strengthened by pasted steel plates. therefore, the pasted steel plate reinforcement method can effectively restore the horizontal connection between the hollow slabs and meet the use of bridge structures.

Detection and Damage Evaluation of Hinge Joints in Hollow Slab Bridges Based on a Light-Load Field Test

The hollow slab bridge is a widely used bridge type for urban bridges. The slabs are prefabricated in a factory and are assembled on site, and then the hinge joints are poured on site. Shallow hinge joints have been used in most existing hollow slab bridges, which commonly bring inadequate connection to the adjacent slabs and probably result in bridge damage. Traditional detection and test methods for hinge joints interrupt traffic, which is inconvenient for local commuters. In the present study, a light-load field test method for hinge joints was proposed. The principles and procedures of the light-load test were concluded and provided based on the test results of 96 spans. The theoretical and measured lateral load distribution ratios were calculated and compared based on hinge joint plate theory. The damage evaluation method and damage classification for hinge joints were defined based on the test results of 1100 hinge joints. Furthermore, the accuracy of the proposed method was verified by a destructive experiment. The research results indicate that the light-load field test and the damage evaluation method for hinge joints are indeed convenient, reliable, and economical, and deserve practical spread and repetition in this area.