Hollow Slab Beam Research Articles

Experimental investigation and evaluation of shear performance of hollow slab beams strengthened by cavity grouting method

After 20 years of service, multiple web shear cracks were observed in 20 m-span prestressed concrete hollow slab beams. Shear enhancement is required to improve structural safety. To evaluate the strengthening effect of the new material on the hollow slab beam structure, fiber-reinforced cementitious composites (FRCC) were used to fill the cavities at the beam ends, and a comprehensive field load test was carried out on the shear-resistant performance of the actual bridge. The web principal stresses changed before and after strengthening under various working conditions, which were analyzed and compared with the performance of the traditional channel steel technique. The findings show that the web principal stresses are significantly reduced by more than 50 % after filling with FRCC, notably superior to the channel steel technique. In addition, both methods can reduce mid-span deflections by 10–20 %. The channel steel technique specifically enhances transverse connection capabilities. Furthermore, strain responses in the beam end sections were reduced by about 30–45 %. Finally, finite element simulations of single beam strengthening were also conducted to complement the experimental analysis. The simulation results show that the shear span ratio (λ), FRCC length and strand prestress loss remarkably impact the strengthening effect. The ultimate load capacity of the strengthened specimens decreases with the increase of λ and prestress loss and increases with the increase of FRCC length. In conclusion, the utilization of FRCC presents a superior alternative for shear enhancement in prestressed concrete hollow slab beams, offering substantial reductions in web principal stresses and enhanced structural performance compared to the traditional strengthening method.

Theoretical and finite element analysis of engineered cementitious composite (ECC) link slab in hollow slab beam bridge base on different load conditions

In order to reveal the feasibility of engineering cementitious composite (ECC) link slab applied to hollow slab beam bridge, the construction process of ECC link slab was simulated based on the birth-death element method and tracking element. Nonlinear analyses of ECC link slab under six load conditions were carried out based on Chinese bridge code. The theoretical formulas are derived and calculated for three of the unfavourable conditions. Finally, the effects of five support conditions on ECC link slab were analysed. The results show that the maximum tensile stresses of the ECC link slab under the overall cooling and negative temperature gradient are 3.569 MPa and 3.440 MPa, and the ECC material has entered plasticity. Theoretical calculations and finite element (linear) results are similar and conclude that temperature-induced axial deformation is the main cause of ECC link slab damage, especially the overall cooling and negative temperature gradient. At the same time different support conditions do not change this result, but rubber bearings can well improve the force behaviour of ECC link slab due to its good deformation coordination ability.

Experimental study on stiffness deterioration of cracked RC hollow-core slab beams

To accurately assess the performance degradation of RC hollow-slab beam after service, in-situ static load tests were carried out on a RC hollow-slab beam bridge with a span diameter of 11.25 m, which is part of the Chongqing–Chengdu Highway Viaduct. Indoor single-girder static load tests were also carried out to study the deflection concrete strain and reinforcement strain at key locations on the hollow-slab beam. Crack development was recorded to investigate the stiffness degradation law of hollow-core slabs. Inverse secant stiffness–residual deflection and inverse secant stiffness–maximum crack width relationship models were established. Results show that the calibration coefficients obtained in the in-situ static load tests were greater than one, indicating potential for stiffness deterioration and insufficient structural safety reserves during service. The initial crack width was increased and extended upwards before the test beam yielded, with many new vertical cracks in the pure bending zone which extended continuously. The slope of deflection curve was larger before yielding and smaller after yielding, the secant stiffness of RC hollow-slab beam was exponentially decreased with load before yielding and changed linearly with load after yielding. The inverse secant stiffness–residual deflection and inverse secant stiffness–maximum crack width curves of the test beam were approximately bilinear, with a larger slope at the beginning of the test and a smaller slope in the plastic phase.

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.

Experimental Study on the Bending Resistance of Hollow Slab Beams Strengthened with Prestressed Steel Strand Polyurethane Cement Composite

In order to explore the toughening performance and failure mechanism of hollow slab beams strengthened with prestressed steel strand polyurethane cement composite, three test beams (L1–L3) were strengthened and one test beam (L0) was used as a comparison. The influence of different tensile stresses of steel strand and fiber additions on the flexural bearing capacity of the hollow slab beams, was studied. The cracking characteristics, load deflection relationship, ductility and strain of each test beam were compared and analyzed. The test results showed that the toughened material was well bonded to the hollow slab beam and the steel strand, which effectively inhibited the development of cracks in the test beams. The flexural bearing capacity of the strengthened test beams was significantly improved. The use of prestressed steel strand polyurethane cement composite material effectively improved the flexural bearing capacity of the test beams, and this reinforcement process can be further extended to engineering applications.

Research on Flexural Bearing Capacity of Reinforced Hollow Slab Beams Based on Polyurethane Composite Material Positive and Negative Pouring Method

In order to explore the construction technology of prestressed steel strand–polyurethane cement composites for strengthening hollow slab beams, two reinforced test beams (L1, L2) and one unreinforced test beam (L0) were subjected to flexural static load tests. The deflection, ductility, stiffness, strain, and bearing capacity of each test beam were used to summarize the influence of different reinforcement techniques on the flexural performance of hollow slab beams. Research shows the prestressed steel strand–polyurethane composite material was well-bonded to the hollow slab beam, which effectively inhibits the development of concrete cracks and delays the damage process of hollow slab beams, that the reinforcement effect of the test beam L1 under the reverse pouring process was remarkable, and the bending performance of the test beam L2 under the forward pouring process of the simulated real bridge was good, which was much better than that of the unreinforced beam L0. The use of tensile prestressed steel strands and forward casting of polyurethane–cement composite materials effectively improved the flexural bearing capacity of the test beams, and this reinforcement process can be further extended to engineering applications.

Temperature distribution simulation and thermal properties investigation of hollow slab beam based on meteorological data

Natural environment has a great impact on the performance of bridge structures, such as the ambient temperature, solar radiation, climate extremes and so on. Due to the lack of regional pertinence in the provisions of the existing specifications on the temperature load standard, and the lack of verification of its adaptability of hollow slab beam bridge in the reconstruction and expansion project, it is necessary to study the temperature load of the beam based on the temperature data of the area where the bridge site is located. Based on the measured meteorological data, the cross-section temperature distribution characteristics of the hollow slab beam and the temperature load effect were investigated. The vertical temperature load model of the short and medium-span hollow slab beam was proposed according to the simplified temperature curve. Firstly, based on the annual measured meteorological data, the plane model was established to analyze the temperature distribution characteristics of the hollow slab beam. Secondly, according to the temperature field distribution of the beam cross-section, the solid model of 16 m hollow slab beam was established to analyze the distribution of the temperature load effect. Finally, based on the preliminarily proposed temperature curve, vertical temperature load models were proposed by introducing the theory of extreme value extrapolation. The studies have shown that the temperature of the hollow slab beam is approximately horizontal distributed, and temperature extreme value appear at the location of the beam web. The roof and floor of the hollow slab beam are compressed and the webs are tensioned in the positive temperature difference state, the stress condition is opposite under the negative temperature difference state. The positive and negative temperature load models can meet the extrapolation requirements of the bridge design reference period. This study innovatively proposed a temperature load model based on the temperature curve corresponding to the most unfavorable effect of the beam. The extrapolation idea in the derivation of vehicle load model is introduced as well. And a temperature load model suitable for the extension of hollow slab bridges in Guangdong is established in this study.

Multifractal analytical method and experimental study on crack evolution of dismantled RC hollow-slab beam

Reinforced concrete is the earliest and most commonly used bridge construction material and there are a large number of RC bridges in service all over the world. Due to a long-time operation and external load, most concrete bridges suffer from various degrees of damage. The most common method used in the maintenance of these bridges is visual inspection, which is highly subjective, lacks quantitative means and provides little information about the mechanical properties of the structure. Therefore, this paper conducts a set of failure experiment of the reinforced concrete hollow slab beams based on multifractal theory, and then proposes a convenient damage detection method for reinforced concrete beam bridges based on crack distribution images. Firstly, this paper introduces the basis of multifractal theory and an example of its application to the cracking characteristics of concrete beam members. Then a set of failure experiment on demolished members of in-service reinforced concrete hollow slab bridges was conducted, and two high-precision industrial cameras were used to record the full process of crack development on the surface of the beams. Then the multifractal theory was used to quantitatively characterize the crack distribution characteristics of the beams during the load process. The function relationship between the fractal dimension and the bending moment and the main mechanical properties (mid-span deflection, maximum crack width) of the test beam was analyzed and the damage index based on fractal dimension is calculated. The results show that the multifractal theory performs appropriate in describing the crack distribution of the beam, the points on the multifractal spectrum continuously move to larger values as the bending moment increases, and the generalized fractal dimension values have similar conclusions. The functional correlation between main mechanical properties and the fractal dimension is strong. Based on the experiment results, the damage classification criteria for reinforced concrete bridges are proposed referred to the IAEA guidelines. Three damage classes and corresponding the range of values of fractal dimension (FD) and the damage index (DI) are given. These findings provide a useful tool for exploring the cracking performance and rapid detection of reinforced concrete bridges.

Comparison of flexural capacity of different hollow slab beams with/without pavement layer reinforced by steel plates

PurposeReinforcement of reinforced concrete (RC) beams in-service have always been an important research field, anchoring steel plate in the bottom of the beams is a kind of common reinforcement methods. In actual engineering, the contribution of pavement layer to the bearing capacity of RC beams is often ignored, which underestimates the bearing capacity and stiffness of RC beams to a certain extent. The purpose of this paper is to study the effect of pavement layer on the RC beams before and after reinforcement.Design/methodology/approachFirst, static load experiments are carried out on three in-service RC hollow slab beams, meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Last, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.FindingsThe experimental results showed that pavement layers increase the flexural capacity of hollow slab beams by 16.7%, and contribute to increasing stiffness. Ductility ratio of SPRCB3 and PRCB2 was 30% and 24% lower than that of RCB1, respectively. The results showed that when the steel plate thickness was 1 mm–6 mm, the bearing capacity of the hollow slab beam increased gradually from 2158.0 kN.m to 2656.6 kN.m. As the steel plate thickness continuously increased to 8 mm, the ultimate bearing capacity increased to 2681.0 kN.m. The increased thickness did not cause difference to the bearing capacity, because of concrete crushing at the upper edge.Originality/valueIn this paper, based on the experimental study, the bearing capacity of hollow beam strengthened by steel plate with different thickness is extrapolated by finite element simulation, and its influence on ductility is discussed. This method not only guarantees the accuracy of the bearing capacity evaluation, but also does not require a large number of samples, and has certain economy. The research results provide a basis for the reinforcement design of similar bridges.

Flexural bearing capacity of RC hollow slab beam strengthened by steel plates of different thicknesses

PurposeThe flexural reinforcement of bridges in-service has been an important research field for a long time. Anchoring steel plate at the bottom of beam is a simple and effective method to improve its bearing capacity. The purpose of this paper is to explore the influence of anchoring steel plates of different thicknesses on the bearing capacity of hollow slab beam and to judge its working status.Design/methodology/approachFirst, static load experiments are carried out on two in-service RC hollow slab beams; meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Finally, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.FindingsWhen steel plates of different thicknesses are adopted to reinforce RC hollow slab beams, the bearing capacity increases with the increase of the steel plate thickness in a certain range. But when the steel plate thickness reaches a certain level, bearing capacity is no longer influenced. The displacement ductility coefficient decreases with the increase of steel plate thickness.Originality/valueBased on experimental study, this paper makes an extrapolation analysis of the bearing capacity of hollow slab beams reinforced with steel plates of different thicknesses through finite element simulation and discusses the influence on ductility. This method not only ensures the accuracy of bearing capacity evaluation but also does not need many samples, which is economical to a certain extent. The research results provide a basis for the reinforcement design of similar bridges.

Shear behaviors of hollow slab beam bridges strengthened with high-performance self-consolidating cementitious composites

A novel strengthening method was proposed to improve the shear behaviors of hollow slab beam bridges through filling the hollow with high-performance self-consolidating cementitious composites. The strengthening effect was evaluated through a field loading experiment and long-term monitoring. Some important parameters were compared and analyzed before and after the strengthening, including the principal stress of the bridge web, the strain response of beam bottom, the mid-span deflection and the transverse connection between the beams. The experimental results showed that the principal stress of the bridge was decreased by more than 50% compared with that before the strengthening. Under different loading conditions, the strain response of each slab beam bottom was decreased in different degrees, with a reduction range between 20% and 60%. The mid-span deflection of the bridge decreased by 10%-25% after the strengthening. Through the analysis of the transverse distribution of the strain on the beam bottom, the strengthening method also improved the lateral connection of the bridge in a certain extent. In addition, it was found that the long-term effectiveness of the strengthening method is verified through more than a year of monitoring.

Study on performance of prestressed concrete hollow slab beams reinforced by grouting with ultra-high performance concrete

To reinforce the inclined web shear crack in the shear span of the prestressed concrete hollow slab beam (PCHSB) on a bridge running for 20 years, a new method of grouting reinforcement was developed. Meanwhile, the grouting material corresponding to this method was developed, so as to improve the shear bearing capacity of prestressed concrete hollow slab. To verify the mechanical performance and reinforcement effect of the strengthened PCHSB, the shear resistance tests were carried out to three pieces of full-scale 20m prestressed concrete hollow slab beam after perfusing reinforcement, whose grouting length was 1.5m, 2.0m, 2.5m respectively. The concrete strain, stiffness, bearing capacity, deflection, crack distribution of beams with different perfusing lengths were tested and compared with those of the beam before reinforcement. The results indicated that the new method of grouting reinforcement with UHPC at the end of the beam could improve the mechanical properties of the beam effectively. The grouting material and the original beam had good cooperative working performance under the test load, which could help to improve the shear bearing capacity effectively, and inhibited the development of oblique cracks. Beyond structural test, temperature of the inner structure was onbseved through a temperature sensor. The evolution of temperature showed the temperature peak UHPC material was reduced significantly. Furthermore, the UHPC material had good filling effect after the reinforced beam was cut apart.

Experimental Study on Residual Bearing Capacity of Existing Prestressed Concrete Hollow Slab Beam

Through the reconstruction and expansion of expressway, it has become the new normal of expressway construction in China to improve the traffic capacity and operation service level of the existing road. However, the reconstruction and expansion of expressways are faced with problems such as the degradation of the existing bridge performance and the original design bearing capacity that can’t meet the current load standards, which restrict the full utilization of the existing expressway bridges. Based on the reconstruction and expansion project of Beijing-Shanghai Expressway (Shandong section), this paper selects the prefabricated and prestressed concrete (PC) simply supported slab bridge with span of 10m and 13m. It evaluates the bearing capacity of HSB based on technical condition checking calculation and load test, and carries out the ultimate bearing capacity test at the same time. According to the checking calculation of bearing capacity and test results, it is concluded that the technical condition of the existing bridges in the expressway (Shandong section) is evaluated as class 1 prefabricated simply supported slab bridge. By adding 150mm integral cast-in-place pavement, the bending capacity of the HSB in the mid of span section meets the current load standard, while the shear capacity of supporting point section does not meet the current load standard, but the difference is within 5%. After the reconstruction and expansion of expressway, the existing bridges mainly bear the load of small vehicles, the load effect is far lower than the current load standard, the bearing capacity meets the current load standard, and can be fully utilized in its original state.

Experimental study on shear behavior of hollow slab beam strengthened with pasting steel plates

PurposeConsidering the “size effect” and the properties degradation of building materials on the strengthened engineering, in this paper, the technology of pasting steel plate was adopted to shear strengthen a 16 m prestressed concrete hollow slab, which had serviced 20 years in cold regions. The shear properties of shear strengthen beams are analyzed.Design/methodology/approachShear loading test of the shear strengthened beam and the contrast beam was conducted. Then the mechanical characteristics, failure mechanism, the mechanical response and shear capacity of shear strengthened beam and contrast beam had been discussed.FindingsThe failure mode of shear strengthened beam and contrast beam was shear compression failure, and the bond failure between concrete and prestressed reinforcement happened in both of test beams. The shear strengthening method of pasting steel plate can effectively improve the mechanical response for the shear strengthened beam. Compared with the contrast beam, the cracking load and failure shear capacity for the shear strengthened beam can be effectively increased by 12.2 and 27.6%, respectively.Originality/valueThe research results can be a reference for the detection and evaluation of shear strengthened bridges, which are strengthened by pasting steel plate. Engineers can refer to the shear strengthening method in this paper to strengthen the existing bridge, which can guarantee the safety of shear strengthened bridges.

Study on Fatigue Characteristics of Carbonation Erosion Prestressed Hollow Slabs in Whole Life Cycle

In this paper, the whole life cycle (failure‐reinforcement‐failure) durability and related fatigue properties of prestressed hollow beam under carbonation erosion environment were studied. According to a 20 m hollow slab beam, the model of prestressed hollow beam was designed and made, and the durability and fatigue tests for the whole life cycle of prestressed hollow beam were carried out. The results showed that the compressive strength and elastic modulus of the specimens increased by about 20% under the action of carbonization erosion. With the increase of fatigue loading cycles, the crack occurrence and development speed of carbonized erosion components were greater than those of healthy components, and the fatigue life decreased sharply from 3 million cycles to 50,000 cycles. Pasting carbon fiber and steel plate had better reinforcement effect on the damaged prestressed plate beam and could help improving the fatigue life of the reinforced component. Comparing the reinforcement of different strengthening methods, it is found that the steel‐plate‐reinforced components have better mechanical properties and antifatigue attenuation characteristics than the carbon‐fiber‐reinforced ones. The research results have important theoretical value for improving the durability of structure and prolonging its service life.

Experiment and Numerical Simulation of the Dynamic Response of Bridges under Vibratory Compaction of Bridge Deck Asphalt Pavement

Vibratory compaction of bridge deck pavement impacts the structural integrity of bridges to certain degrees. In this study, we analyzed the dynamic response of different types of concrete-beam bridges (continuous beam and simply supported beam) with different cross-sectional designs (T-beam and hollow-slab beam) under vibratory compaction of bridge deck asphalt pavement. The dynamic response patterns of the dynamic deformation and acceleration of bridges under pavement compaction were obtained by performing a series of field experiments and a three-dimensional finite element simulation. Based on the finite element model, the dynamic responses of bridge structures with different spans and cross-sectional designs under different working conditions of vibratory compaction were analyzed. The use of different vibration parameters for different bridge structures was proposed to safeguard their structural safety and reliability.

Analysis of Influence of Hinge Condition on Overall Mechanical Performance of Hollow Slab Beam

The concrete hinge joint is a widely used connection method for the assembled hollow slab bridge, and it is also a place where the disease is extremely easy to appear. Through the study of four different simplified calculation modes of the hinge joint, the transverse distribution coefficient of the hollow slab beam under different working conditions is compared and analyzed, and the influence of the hinge joint on the overall mechanical performance of the structure under different working conditions is obtained. It is found that the difference of the simplified mode has a great influence on the calculation of the lateral distribution of the bridge; the complete failure of the joint will lead to a drastic change in the lateral distribution coefficient of adjacent hollow slab beams, and even the phenomenon of single beam appear. At the same time, combined with the research results, reasonable suggestions for the design stage and actual operation stage of hinge joint of the hollow slab beam are put forward.

Calculation on the flexural stiffness of the section of PC hollow slab beam in the life cycle

PurposeDuring service period, due to the overload or other non-load factors, cracks of the pre-stressed concrete beam are seriously affecting the safety of the bridge structure. The purpose of this paper is to quickly realize the bearing capacity and the loss of the section stiffness through fracture characteristics and make correct judgments.Design/methodology/approachThrough the flexural failure test of two test beams: collecting data of fracture characteristics and section stiffness loss value. According to the fracture characteristic data, the flexural stiffness of the section is obtained by the nonlinear calculation method, and the results are verified by test data. Data regression method is used to establish the section flexural stiffness loss ratio calculation formula, nominal tensile strain at the bottom edge of the cross-section used as a variable factor, and the accuracy of this formula is verified by comparing the flexural failure test results of pre-stressed hollow plates.FindingsThe loss of the flexural stiffness of section shows the decrease trend of first-fast-then-slow and the structural stiffness is sensitive to the initial cracking of beam. The calculation formula on the loss ratio of the flexural stiffness of section established with the nominal tensile stress at the bottom edge of beam as a variable is accurate and feasible, it realizes the possibility of assessing the stiffness loss of pre-stressed concrete structure by adopting the statistic parameters on crack characteristics.Originality/valueA method for quickly determine the stiffness loss of structures by using fracture characteristics is established, and using this method, engineers can quickly determine whether a bridge is a dangerous bridge, without loading test. So, this method not only ensures the safety of human life, but also saves money.

Static Loading Test and Evaluation of Single Beam of Highway Prestressed Concrete Hollow Slab Beam Bridge

Since the main beams of a prestressed concrete hollow slab beam Highway Bridge stored for too long, in order to assess its bearing capacity, static loading test and bearing capacity evaluation of single beam was conducted. The hollow slab beam at the locations where the transverse distribution coefficient is biggest was chose for testing, and the transverse distribution coefficient at midspans of the slab beam was calculated by the hinged slab method. By comparing the theoretical and measured values of displacement and stain at key points of the beam, structural performance of the beam was finally evaluated. The test results showed that both the strength and stiffness of the beam was conforming to the requirements of the specification and able to satisfy normal use requirements in serviceability limit state.

A brief discussion on the construction technology of replacing hollow slab beam support by synchronous jacking with bullleg method

A brief discussion on the construction technology of replacing hollow slab beam support by synchronous jacking with bullleg method