Transverse Load Distribution Research Articles

Nonlinear dynamic study of FG-GFRC-NPR structures

The functionally graded glass fibre-reinforced polymer composite(FG-GFRC) is one of the contemporary sophisticated materials that may be employed for a variety of technical purposes. The shock absorption capacity of FG-GFRP laminates can be improved by incorporating auxetic property (i.e., negative Poisson's ratio NPR) in the structures, which can be attained by a particular stacking sequence of glass fibres (GF) and a different percentage of GF distribution along the thickness direction within the FG-GFRP structure. The nonlinear dynamic behaviour of such structures must be investigated. The clamped-clamped FG-GFRP-NPR structure is stimulated under a uniform transverse load distribution in the current work. Based on the higher-order shear deformation theory (SDT), the displacement field and nonlinear stress–strain relationship are derived. The nonlinear differential equation with cubic non-linear components were derived using Hamilton’s principle and transformed using Galerkin’s technique and obtained governing equation of motion. MATLAB has been used to conduct all numerical simulations. A time series, a phase picture and a Poincare diagram (PCM) were generated to characterize the vibration behavior of such auxetic structures.

Reinforcement of Insufficient Transverse Connectivity in Prestressed Concrete Box Girder Bridges Using Concrete-Filled Steel Tube Trusses and Diaphragms: A Comparative Study

To address the issue of insufficient transverse connectivity in prestressed concrete box girder (PCB) bridges, this study investigates two transverse strengthening methods—installing diaphragms and utilizing concrete-filled steel tube trusses (CFSTTs). A finite element model was developed for a typical 30 m PCB bridge and was validated by on-site load test results for reliability. Based on the deflection and load distribution of PCB bridges before and after reinforcement, as well as the maximum stress and strain of the diaphragms and the CFSTTs, comparative analyses were conducted on diaphragms of different thicknesses and materials, as well as on CFSTTs of various strength grades. The results show that the addition of a transverse partition and CFSTTs can effectively improve the load distribution of the PCB bridge and reduce the maximum deflection of the girder, especially when using the CFSTT reinforcement method. The unique structural design improves the reinforcement effect of the material in the post-elastic stage. When using CFSTTs, increasing the steel tube wall strength significantly reduces the maximum deflection of the main girder. For example, using steel tubes with yield strengths of 235 MPa and 420 MPa filled with concrete of 50 MPa compressive strength reduced the maximum deflections by 15.32% and 24.55%, respectively, and improved the load distribution coefficients by up to 7.31% and 11.57%. Additionally, steel diaphragms demonstrated better reinforcement effects compared with concrete diaphragms. The load transverse distribution coefficients for the CFSTT-reinforced PCB bridge were calculated using the hinge plate (beam) and the rigid plate (beam) methods, showing minimal differences between the two approaches. The findings of this study provide valuable insights into the design of diaphragm and CFSTT reinforcement in PCB bridges, aiding in the selection of optimal reinforcement strategies.

Simplified Analytical Approach for Calculating the Transverse Load Distribution of Precast Slab Bridges with and without Concrete Overlays

Simplified Analytical Approach for Calculating the Transverse Load Distribution of Precast Slab Bridges with and without Concrete Overlays

Improved theoretical calculation method for the transverse load distribution of wide bridges considering torsion and distortion

An improved theoretical calculation method was proposed to determine the transverse load distribution of airport and highway bridges under heavy loads using the rigid-joint girder (RJG) method. The effects of torsion, distortion, and vertical inclination of the adjacent box girder joints under an eccentric heavy load were considered. The coefficients and influence lines of a taxiway bridge and a highway bridge were calculated using the proposed method, the RJG method, and the modified RJG methods. The accuracies of the three methods were evaluated by the refined finite element model, and the cosine similarity and peak deviation rate were used as quantitative indices. The results showed that the cosine similarity obtained from the proposed method for the taxiway bridge was 0.996 compared with the finite element method (FEM). The maximum peak deviation rate of the transverse load distribution coefficient for the proposed method was 14.88 % and obviously lower than 34.74 % for the RJG method. For the highway bridge, the cosine similarity of the influence line derived from the proposed method was 0.995, and the maximum peak deviation rate of the transverse load distribution coefficient for the proposed method was 6.66 % and lower than 16.14 % for the RJG method. The results indicate that the proposed method can be used to calculate the transverse load distribution of wide box girder bridges accurately and efficiently.

ONE-WAY SLABS IN TRANSITION BETWEEN ONE-WAY SHEAR AND PUNCHING: EXPERIMENTS AND RECENT INSIGHTS FOR EVALUATION

Bridge deck slabs are members on which one-way reinforced concrete slabs are found frequently loaded by concentrated loads. Although the one-way shear failure mechanism has gathered more attention in the past years, both one-way shear and two-way shear mechanisms may be critical for such loading conditions. This paper addressed the ultimate capacity of thin one-way reinforced concrete slabs subjected to concentrated loads and yielding of the flexural reinforcement. In practice, the test setup studied was devised to represent short-span rural bridges frequently found in Brazil. The experimental program included 12 tests performed on 6 slabs applying the concentrated loads at varied positions. All tests started to fail by punching shear. Nevertheless, both one-way shear and punching shear cracks were observed at ultimate states after shear redistribution. The reinforcement yielding followed by excessive flexural cracking hampered the arching action activation for loads closer to the support. The comparison of experimental and calculated resistances using standard code-based expressions suggests that improvements in unitary shear capacity could be supported as a result of slabs' transverse load distribution capacity. Alternatively, increasing the effective shear width can help estimate one-way shear capacity for loads near to the support.

Level 3 Assessment of Highway Girder Deck Bridges according to the Italian Guidelines: Influence of Transverse Load Distribution

The Italian Ministry of Infrastructure and Transportation adopted the guidelines on risk classification and management, safety assessment and monitoring of existing bridges through the Decree No. 578 dated 17 December 2020. This document must be used by all managing entities to prevent damage due to a lack of maintenance to these crucial components of the infrastructure system. The approach of the guidelines for existing bridges is developed across six levels, ranging from Level 0 to Level 5. The research work presented in this article is focused on Level 3, which pertains to preliminary assessments conducted on existing bridges. Through an automated procedure, the preliminary verification is performed by comparing bending and shear stress generated by traffic load schemes extracted from previous standards with the ones based on the current code. These loads are applied to a series of girder deck models, selected through a statistical study conducted on a database of bridges. Performance indices are derived from the comparison to evaluate the adequacy of previously designed and constructed structures by applying the load models specified in the current regulations for designing new bridges. The analysis results highlight a performance gap, which varies depending on the standard code at hand.

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.

Transfer Matrix Method for Calculating the Transverse Load Distribution of Articulated Slab Bridges

Articulated slab bridges have been widely used by transportation administration for short-to-medium span bridges because of their good economy, convenient construction, and environmental advantages, while the presence of shear keys increases the complexity of structural behavior. Developing more reasonable analysis approaches of quick assessment, pre-design, and hand calculations for the articulated slab bridges is a challenge because of the peculiar shear key mechanism. This paper is devoted to presenting a recursive algorithm, based on the force equilibrium conditions of each individual slab, thus resulting in simultaneous equations of the transfer matrix method (TMM). In this procedure, the state vector is an array composed of vertical displacement, shear force, unit constant; and the transfer matrix contains the bending and torsional stiffness parameters of simply supported slabs. Then, the influence line of transverse load distribution (TLD) is calculated for each slab by introducing boundary conditions. To validate and verify the efficiency of the TMM algorithm, a transversely prefabricated void slab bridge with a span of 20 m is considered as a case study. The traditional force (FM) and finite element (FEM) methods are used for comparison and validation. It is demonstrated that the TMM can provide good results with higher algorithm efficiency by exempting the modeling tasks in FM and FEM and capture variations in TLD along the bridge’s span. In addition, the influence of the span length and relative stiffness coefficient of slabs on the TLD of articulated slab bridges are analyzed from the parametric analysis.

Adding composite truss to improve mechanical properties of reinforced concrete T-girder bridge

To solve the problem of insufficient transverse connection of T-girder bridges, this paper investigated the strengthening method of two composite trusses symmetrically installed in mid-span. The composite truss included two top plates, four diagonal braces, and one horizontal brace. An experimental investigation was carried out to study the mechanical properties of reinforced concrete T-girder using single-point loading method under four load cases. The experimental results showed that the maximum transverse stiffness of T-girder specimens strengthened with composite trusses improved by 12.4% compared with control beams. Simultaneously, it had an excellent restraining effect on the cracks development. The maximum percentage decrease in the deflection corresponding to the maximum load when the reinforced concrete T-girder strengthened with composite trusses over the control beam of up to 39.7 was observed. In addition, the load transverse distribution coefficient was investigated according to rigid-jointed slab (girder) method. The composite trusses were chosen as intermediate diaphragm to calculate moment of inertia. The analytical model was in an accurate with the experimental result under the same loading condition. The optimize spacing of composite trusses was given from 600 mm ( L/10) to 1200 mm ( L/5), and thickness of top plate was 30 mm when the load transverse distribution coefficient was homogeneously distributed. Finally, a three-dimensional finite element model was used to evaluate the effectiveness of composite trusses.

Finite-Element Analysis of Adjacent Concrete Box Girders Transversely Post-Tensioned at the Top Flanges Only

A three-dimensional non-linear finite-element model (FEM) was constructed using a commercial software (ATENA-Studio) to investigate the transverse load distribution behavior of adjacent precast prestressed concrete box-girder bridges. An innovative connection between box girders was used, where transverse post-tensioning was applied at the top flanges only eliminating the need for intermediate transverse diaphragms. The FEM was validated in terms of deflections, strains, cracking and ultimate loads against experimental results previously reported by the authors. The validated FEM was then used to perform a parametric study investigating the influence of adding concrete topping, load location, and bridge width on the transverse load distribution behavior of the newly developed connection. The results of the FEM demonstrated the efficiency of concrete topping in limiting mid-span deflections up to 25%. Additionally, the maximum live load moment distribution factors (LLMDFs) for different load locations and bridge widths were evaluated.

Investigation on aerodynamic characteristics for steel tubular cross-arms of transmission tower under skew wind

A study of the aerodynamic characteristics of steel tubular butterfly-shaped cross-arms in a transmission tower head under skew wind is presented. A wind tunnel test was conducted under skew wind by using a scaling model, and a numerical simulation was performed with a high-precision three-dimensional tower head model. The drag coefficient, skew wind load factor, and wind load distribution factor of the cross-arms obtained from the experiment and numerical simulation were identified and compared with those acquired from different codes. It is concluded that the indirect force measurement method was found to underestimate aerodynamic forces acting on windward cross-arms. For single cross-arm, the horizontal cross-arm showed stronger shielding effect than the inclined cross-arm. A fitting formula for the skew wind load factor of the cross-arm is proposed, and values obtained from it matched experimental and simulation data well. A comparison between calculated and measured wind load distribution factors showed that although longitudinal load distribution factors calculated with the Chinese standard (2018) were consistent with measured data, calculated transverse load distribution factors did not match measurements well. It is suggested that the effect of the transverse lift wind force should be considered in the calculation of wind load distribution factors.

Evaluating in-service structural behaviour of an operational railway bridge using fibre optic sensing and structural model updating

Multi-girder prestressed concrete bridges are a very common structural form for bridges around the world. Their continued use is expected in the future given the advantages these structures have with respect to speed of construction, reduced maintenance and improved material efficiency. However, the in-service behaviour of these types of structures, such as their load distribution characteristics, support boundary conditions and the contribution of secondary elements, is still not well understood, and few studies have investigated these areas in depth. Gaining better insight into these aspects of bridge behaviour will enable more realistic structural assessment and thus facilitate more targeted maintenance and refurbishment of these bridges. This paper evaluates the in-service structural behaviour of an operational prestressed concrete railway bridge, which has been monitored using a dense network of fibre optic strain and temperature sensors since it was constructed in 2015. In particular, the normalised curvature profiles and the neutral axis positions across the composite solid slab bridge deck may be used to extract information about the bridge’s transverse load distribution behaviour, support boundary conditions and the stiffness contribution of secondary elements. Using this information, structural model validation and updating were performed with the goal of providing a more realistic assessment of structural behaviour and structural capacity. The proposed methodology and workflow in this study provide new insights into the real performance of multi-girder prestressed concrete bridges and thus can be used to improve their operation, maintenance, assessment and refurbishment.

Reliability evaluation method of anti-loosening performance of bolted joints

Loosening failure is a serious failure mode of bolted joints. The anti-loosening performance of bolted joints can be evaluated quantitatively by measuring their critical transverse loads. However, the uncertainty of various technological and structural parameters of bolted joints causes the uncertainty of their critical transverse loads. The reliability of the anti-loosening performance of bolted joints affects the reliability of the equipment being used. In this study, the source, action form and degree of the uncertainty of various technological and structural parameters of bolted joints were analyzed, and the sensitive parameters were screened out. Then, the distribution of the stochastic critical transverse load under the action of uncertain parameters was calculated numerically, and the reliability was obtained by integrating the probability density function. The reliability evaluation method was validated in the entire sample space by finite element analysis. Finally, four different bolted joints were selected as specimens, and the reliability evaluation method was validated by experimental tests. The method proposed in this paper can be used to evaluate the reliability of the anti-loosening performance of bolted joints comprehensively and accurately.

Excel VBA programming with Excel to compute the load tranceverse distribution coefficient of G-M method

In this paper, by analyzing the calculation principles of load transverse distribution coefficient of G-M method, using office software Excel, the calculation model of a universal worksheet is given, making the computation of load transverse distribution coefficient with G_M method more accurate and swift. The model is very practical, and can offer reference for bridge and highway designers.

Study on the Method of Moving Load Identification Based on Strain Influence Line

In order to improve the accuracy of load identification and study the influence of transverse distribution, a novel method was proposed for the moving load identification based on strain influence line and the load transverse distribution under consideration. The load identification theory based on strain influence line was derived, and the strain integral coefficient was proposed for the identification. A series of numerical simulations and experiments were carried out to verify the method. The numerical results showed that the method without considering the load transverse distribution was not suitable for solving the space problem, and the method with the load transverse distribution under consideration has a high identification accuracy and excellent anti-noise performance. The experimental results showed that the speed identification error was smaller than ±5%, and the vehicle speed had no obvious influence on the identification results of the vehicle weight. Moreover, the average identification error of the vehicle weight was smaller than ±10%, and the error of more than 90% of samples was smaller than ±5%.

Dynamic load test and lateral load distribution of a modified rigid frame bridge

In order to evaluate the stress state and working performance of a rigid frame bridge after reconstruction and extension, load test and transverse load distribution were carried out. Static load test is the test of stress at each section of main beam under the action of partial load and medium load. Dynamic load test is used to test the inherent fundamental frequency, damping ratio and impact coefficient of the bridge through pulsation test and sports car test. The results show that the first order vibration of the bridge is mainly transverse vibration from the measured modal parameters, which is consistent with the characteristics of higher pier and greater flexibility. The vibration characteristics of the bridge structure are low frequency and small damping vibration, the value of which belongs to the normal range among similar bridge structures, the overall stiffness of the bridge structure is normal, and the measured impact coefficient during the test of sports car is less than the design impact coefficient, indicating that the dynamic stiffness of the bridge meets the design and specification requirements.

Live-Load Testing of Flat Precast Slab Bridge to Determine Joint Efficiency and Distribution Factors for Moment

AbstractA live-load test was conducted on an in-service bridge containing flat precast concrete slabs. The purpose of the test was to evaluate transverse load distribution and efficiency of the lon...

Effect of Transverse Damage on Transverse Load Distribution of Bridge Side Beam under Moving Load

In order to study the variation of transverse load distribution of T-beam bridge with transverse damage under moving load. In this paper, nine kinds of working conditions are proposed for the possible failure modes and the different locations of the failure, and relevant finite element models are established. Through simulation, the lateral load distribution of middle beams under nine working conditions is obtained and compared with that under non-damage condition. The results show that the transverse load distribution capacity of T-beam bridge under moving load will be greatly affected after the transverse connection damage of the diaphragm beam occurs. When the location of transverse damage is different, the influence of T-beam bridge will be different.

Influence Of Overload On Transverse Distribution Of T-beam Bridge

In order to study the influence of overload on the transverse load distribution of T-beam bridge, according to the different failure position and failure form of main beam, nine working conditions are divided for finite element simulation, and the transverse distribution value of each main beam under each working condition is obtained, and compared with the value under general load. The results show that: if the bridge transverse connection is damaged, the lateral load distribution capacity of the structure will be reduced again, and the stress form of the structure will become more unreasonable.

Mechanical analysis of the structure of longwall mining hydraulic support.

Existing studies of the structural strength of longwall mining hydraulic support are mainly focused on the force acting on individual supports instead of the general mechanical characteristics of the support group in a fully mechanized coal seam working face. This study combines theoretical analyses and experiments to investigate the mechanical characteristics of a longwall mining hydraulic support group and the stiffness of key support components under different working conditions. The theory of a beam on an elastic foundation was applied to construct a mechanical model for the hydraulic support group. The location and the size of loads on the top beam were determined. Field tests yielded data on the deflection of the roof and loading on the support group along the working face, where the stiffness of end supports varies. The transverse load distribution of the top beam and the offset loading coefficient at different locations along the working-face direction were obtained. A three-dimensional model was constructed for the support group while assembling virtual hydraulic supports using modern virtual modeling theories and methods. Finite element analysis was used to analyze the strength of the hydraulic support. The weakest areas of key components were found to be pinholes connecting the column cylinder to the base and roof of the mine. These results can be applied to achieve secure and stable operations of hydraulic supports in the working face of a thin coal seam, thereby improving the safety and production efficiency of mining operations.