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In the engineering structures using circular steel tube (CST), the eccentric loading of CST members often occurs due to installation error and structural form. Existing research mainly focuses on the bearing resistance of circular steel pipes under the condition of eccentricity at one end. In practical application, both ends of CST members also may be eccentric. And with the increase in eccentricity, material yielding may occur prior to flexural buckling. So far, it's lack of reports about the mechanical behavior of CST members subjected to eccentric loading at both ends and the boundary between material yielding and flexural buckling. This paper presents experimental, numerical and theoretical studies on bearing resistance of thin-walled circular steel tube with slenderness ratio of 30, 40 and 50, subjected to eccentric loading at one end and both ends, respectively. The study reveals a significant discrepancy in the prediction of bearing resistance for circular tubes subjected to eccentric loading at both ends according to existing design codes. Considering the synthesis of bending moment and deflection caused by eccentric loading at both ends, the calculation method of the bearing resistance based on flexural buckling of CST is established, which enhances the prediction accuracy of test verification. In addition, a theoretical boundary between the two failure modes appearing in CST members under eccentric loading at one and both end(s) - flexural buckling and reaching the material yielding strength - was established as dominated by the slenderness ratio and loading eccentricity. [ABSTRACT FROM AUTHOR]

Bearings are regarded as a crucial element that impacts the overall performance of the seismic analysis of bridges. The assessment of seismic performance in bridges heavily depends on the nonlinear features of bridge bearings. Therefore, it is essential to simulate the nonlinear mechanical behavior of bridge bearings to attain the required accuracy of seismic analysis. This paper examines the friction features of pot bearings using the Bouc-Wen hysteretic model, based on which a nonlinear model of pot bearings is proposed. The proposed model can rapidly and effectively analyze the nonlinear mechanical behaviors of bridge bearings under horizontal earthquakes by adequately simplifying the mechanical properties of these bearings. The accuracy of the model for horizontal seismic effects analysis is validated using a numerical simulation method. The simulation compares the nonlinear model seismic effects of the bearing with a linear-elastic model that ignores the bearing frictional effects under horizontal seismic action. The results demonstrated that in the proposed nonlinear model, the ratio of the composite bending moment and yield bending moment of the pier bottom section (demand capacity ratio) is lower than that of the linear elastic model, leading to a more accurate analysis of horizontal seismic effects and thus preventing overestimation of seismic consequences. [ABSTRACT FROM AUTHOR]

The large underground structure in saturated stratum is vulnerable to float during an earthquake. This results in a plethora of problems, such as uneven settlement, large internal force and structure damage. In this study, the seismic behavior of a three-story, two-span subway station in complex saturated stratum was investigated through water-soil fully coupled 3D finite element method. In the analysis, the nonlinear soil behavior was described by a cyclic mobility model and the structure was calculated using a nonlinear constitutive model which can consider the influence of axial force on its bending moment. Joints elements were used to model the contact surface between soil and structure. The development of the soil displacement and internal force of the station structure at different times during a huge earthquake was examined. The bearing capacity of the station structure members was analyzed. The results indicated that the vertical displacement was spatially distributed. The larger additional seismic stresses appeared in the bottom slab and side wall. Failed elements were observed in both the walls and slabs, and the walls were more easily damaged than the slab. The results provide useful reference for the large underground structure seismic design in the construction of urban underground space. [ABSTRACT FROM AUTHOR]

As a new type of composite girders, composite girders with corrugated steel webs and concrete-filled steel tubular (CSW-CFST) truss chords are extensively utilized in bridge engineering. To examine the structural behavior of composite girders with CSW-CFST truss chords subjected to combined flexure and torsion, model tests and finite element analysis (FEA) are employed. Using these efficient tools, the strain distribution, deformation law, failure mode, and bearing capacity of these composite girders subjected to pure torsion and combined flexure and torsion are methodically obtained. The primary objectives are to probe the applicability of existing flexure-torsion relation curves and introduce the calculation method for the bearing capacity of composite girders with CSW-CFST truss chords subjected to combined flexure and torsion. The obtained results reveal that their failure mode is influenced by the initial torsional moment. Further, their bearing capacities due to the applied initial torsional and bending moments can be maximally enhanced by about 21.6% and 6.6%, respectively. The deviation between the predicted bearing capacity by the FEA and that obtained from the tests is less than 8.6%, demonstrating the high accuracy of the FEA model. The contribution of the torsional moment to the flexural bearing capacity is either ignored or underestimated by the existing flexure-torsion relation curves, with a minimum deviation of about 22.3%. By comparing the results acquired by the extended FEA and the calculation method proposed in this paper, it is proved that the proposed calculation method for the bearing capacity of composite girders with CSW-CFST truss chords subjected to combined flexure and torsion may reduce the deviation from 22.3% to 8.3%. [ABSTRACT FROM AUTHOR]

This paper discusses the negative bending behavior of a new type of web-embedded U-shaped steel-concrete composite beams (WUSCBs). Considering the effective width of the concrete slab, a negative bending moment test was performed on eight WUSCB specimens. The web-embedded shear connector in the WUSCB has been shown to have good shear connection performance and maintain the overall function of the WUSCB. The failure process of the specimen was categorized by the cracking, yielding, and buckling loads which correspond to 0.29 P u, 0.79 P u, and 0.90 P u, respectively. Negative bending failure was observed in the WUSCB, evidenced by the steel plate yielding and concrete slab cracking. The WUSCB was found to have good ductility and deformability under negative bending. A finite element model was established to verify with the experimental results. The calculation method for negative bending capacity is proposed; and the calculation results are in good agreement with the test results. [ABSTRACT FROM AUTHOR]

Offshore wind turbine is facing with extremely complicated climatic environment. The accurate prediction of wave movement caused by strong typhoons and its action on foundation of wind turbine are crucial. To disclose hydrodynamic characteristics of foundation structure of wind turbine under typhoon-wave-current coupling effect on the sea, a 10 MW super-large offshore wind turbine in Wailuo Wind Farm, Guangdong was chosen as a research object and a real-time meso-scale WRF-SWAN-FVCOM (W-S-F) coupling simulation platform was constructed by using Model Coupling Toolkit The spatial-temporal evolution of typhoon-wave-current in the offshore wind farm was simulated when a super typhoon "Rammasun" passed through. Next, the hydrodynamic load distribution characteristics of single pile foundation of wind turbine were analyzed by combining the meso-micro scale nested method. Extreme load model of foundation piles under different wave phases was proposed. Results demonstrated that the constructed W-S-F platform increased the simulation precision of typhoon path by 42.51% than single WRF model. The horizontal wave force of the foundation pile reached the negative and positive peaks at phases T0 and T4 under typhoon-wave-current coupling, and it presented symmetric distribution circumferentially around the 180° angle of wave attack. The phase T4 was the most adverse phase for the strength design of single pile foundation of offshore wind turbine. At the bottom of foundation, the maximum shear reached the 7.68 × 106 magnitude and the maximum bending moment reached the 5.2 × 108 magnitude. [ABSTRACT FROM AUTHOR]

This study examines experimentally the mechanical performance of composite steel and concrete beams with expansion joints in the concrete slab. Four composite beams with expansion joints in the concrete slab were tested, and various aspects of such beams including the effects of expansion joint locations (L / L 4 4 , 5 L / 5 L 12 12 , and L / L 2 2 , where L = span length), expansion joint sizes (through and half-through of the concrete depth), and loading conditions (positive bending moment and negative bending) etc., were investigated. Load versus vertical deflection responses at key sections, and the strain development and distribution on the steel beam were measured. To explore the behavior of shear connectors on or near the expansion joint sections, the normal strain on shear connectors was measured. The bending strain and axial strain of shear connectors on joint sections were also discussed in detail. The theoretical methods for predicting the rigidities and ultimate load-carrying capacities of the composite beams were examined, and it was found that the current AASHTO-LRFD criterion without considering expansion joints in a concrete slab can still provide conservative estimations of ultimate loads of such beams under a negative moment. For composite beams under a positive bending moment, however, they are not applicable, due to the different failure modes. The test results from this research provide new information for improving the design, construction, management, maintenance, and structural health assessment of such beams that can be used in bridges and buildings, etc. [ABSTRACT FROM AUTHOR]

In conventional seismic design, bridges usually are assumed to be fixed to a rigid support. This assumption, however, does not correspond to the reality of bridges with shallow footings since they can rock in strong earthquakes. It has been recognised that several factors significantly affect the response of bridges with rocking footings, including support flexibility, pier height and pounding. Most studies so far have mainly focused on a single factor. This research aims to narrow the knowledge gap by investigating the combined effect of pier height, support condition and earthquake characteristics on bridges with rocking ability. A series of shake table experiments on a single-frame bridge with different pier heights and support conditions under hard, medium and soft soil excitations were carried out. The influence of support flexibility was examined by comparing the response of rocking bridges on rigid support with that on soil support. The result shows that regardless of the flexibility of the support, in the case of no pounding, it is beneficial to take rocking footing into account because the maximum bending moment at the pier support can be reduced. However, when pounding was considered, the combined effect can generate an even larger maximum bending moment than that of the fixed-base bridge. [ABSTRACT FROM AUTHOR]

Motivated by a curiosity to explore the behavior of innovative arch structures enabled by the use of fiber-reinforced polymer (FRP) composites, this paper proposes a theoretical model built upon an enhanced formulation of the deflection method, broadening its scope to large-curvature problems. Traditionally, the deflection method approximates curvature as the second-order derivative of deflection, a simplification valid only for small curvatures. This limitation poses a challenge when applying the deflection method to problems involving large curvatures, a characteristic inherent in FRP-enabled arches where significant curvatures arise either initially or due to deformation. The enhanced formulation at the core of the proposed model addresses this challenge by incorporating a circular deflection function. This function posits that each deformed segment of the structural member can be represented by a circular arc, with its curvature and length related to the internal axial force and bending moment at the midpoint section of the segment. This feature facilitates the exact representation of curvature, offering the proposed model a unified approach capable of addressing both small- and large-curvature problems. The paper details the formulation and verification of the theoretical model, with an emphasis on its application to representative cases of FRP-enabled arches. [ABSTRACT FROM AUTHOR]

Joints are the most critical component of reticulated shell structures, and their hysteretic performance is crucial to the mechanical properties of the whole reticulated shell structure under seismic action. Therefore, the hysteretic behaviour of aluminium alloy flower-gusset composite joint for an out-of-plane bending moment was studied by experiments and numerical analysis. The results show that the hysteretic curves of flower-gusset composite joints and gusset joints contain four stages: an elastic stage, a bolt slip stage, a hole wall pressure-stiffness degradation stage and a failure stage. The hysteretic performance of the new flower-gusset composite joint is obviously better than that of the traditional plate joint. With the increase in the thickness of the cover plate, the bending stiffness of the flower-gusset composite joint increases significantly, while the rotational deformation decreases. Then, a restoring force model of the flower-gusset composite joint is proposed through theoretical analysis based on experiments and numerical analysis. [ABSTRACT FROM AUTHOR]

A new type of composite structure, the composite box girder with corrugated steel webs (CSWs) and trusses, is proposed recently. In order to investigate the structural behavior under positive and negative bending moments, flexural tests of the continuous girder were carried out, and the failure modes, deformation patterns, strain distribution, and development of the concrete cracks were investigated. Finite element analysis was conducted to investigate the effect of the range of concrete in the steel tube and the thickness of CSWs on the flexural behavior. The experimental and numerical results show that the test beam has a good ductility and integrity under flexural load. The contribution of CSWs to the flexural bearing capacity is very small and can be neglected. Besides, the plane section assumption is still valid when only top concrete slab and bottom steel tubes are concerned. The concrete filled in bottom steel tubes increases the stiffness and the bearing capacity of the girder. Equations to calculate the flexural bearing capacity under positive and negative bending moments were put forward and then verified with experimental results. [ABSTRACT FROM AUTHOR]

The study of reinforced concrete members subjected to combined loads always has been an important research topic in the field of engineering, but the torsional behavior of T-shaped reinforced concrete members subjected to combined loads has yet to be determined. This paper is focused on providing a detailed explanation of the torsional behavior of T-shaped reinforced concrete members subjected to combined compression-bending-shear-torsion. From the perspective of experimental tests and numerical analyses, in this paper, we discuss the effects of combined loads on the torsion bearing capacity, the development of cracks and the failure mode, strains of key points in the concrete and longitudinal reinforcement, and the relation of torsion and angular displacement. We conducted experiments and numerical analyses of four groups of reinforced concrete members by using the main variables of the axial pressure ratio and the bending moment. Also, the experimental and calculated results are compared based on the elastic-plastic damage constitutive model of concrete. Based on the test data and the existing formula, we also extended the formula used to calculate the torsion bearing capacity and provided diagrams of the interaction when combined loads were applied. In addition, the results of this study highlight the turning point from torsion failure to compression-bending-torsion failure. The test results demonstrated that torsion capability increases in the specified range of axial pressure ratio and decreases as bending increases. The test results also indicate the importance of considering the effects of compression-shear-bending on the torsion bearing capacity in the engineering design. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the moment carrying behavior of typical Tibetan timber beam-column joints under monotonic vertical static load and also evaluate the influence of length ratio of Gongmu to beam (LRGB) and dowels layout on the structural performance of the joint. Six full-scale specimens were fabricated with same construction but different Gongmu length and dowels position. The moment carrying performance of beam-column joints in terms of failure mode, moment resistance, and rotational stiffness of joints were obtained via monotonic loading tests. Test results indicated that all joints are characterized by compressive failure perpendicular to grain of Ludou. Additionally, it was found that greater LRGB leads to greater initial rotational stiffness and maximum moment of the joint by an increase of restraint length for beam end; however, offsetting dowels toward column resulted smaller stiffness and ultimate bending moment of joints, particularly, offsetting Beam-Gongmu dowels toward column changed the moment-rotation curve pattern of the beam-column joint, accompanied by a hardening stiffness at last phase. Furthermore, a simplified trilinear model was proposed to represent the moment-rotation relationship of the typical Tibetan timber beam-column joint. [ABSTRACT FROM AUTHOR]

This paper numerically investigates the validity of Rayleigh damping model considering explicit operator to assess the dynamic response of high rise buildings under seismic loads. Considering transverse and longitudinal seismic waves, the bending moment, shear force, axial force, and and inter story drift are evaluated for a Core wall and a frame system of 46 story each. It is found that considering the explicit scheme, the dynamic responses are amplified significantly especially for axial forces. The reported amplification can be attributed to the ignorance of stiffness proportional Rayleigh damping coefficient which is associated with the stability issue of the implemented explicit operator. The paper indicates that Rayleigh damping model does not provide the required/expected damping for the higher modes of higher frequencies hence, it is not appropriate to be used along with the explicit operator especially for buildings of wide range of frequencies. It is worth pointing out that for classical dynamic analysis which follows the implicit scheme, Rayleigh damping seems to well consider the higher modes of high frequencies with higher damping ratio in comparison to the initial mode shapes. Consequently, the literature explicit scheme should be revised to accurately consider a proper damping for the higher modes which is crucial to assess the total response of structures of long periods and wide range of frequencies such as high rise buildings among others. [ABSTRACT FROM AUTHOR]

With the development of society, portal frame has been increasingly used in industrial buildings because of light weight, high degree of industrialization, and high economic efficiency. Some existing portal frames need to be reinforced and improved due to the expansion of production and the functional change. As a safe, reliable, and convenient reinforcement method, the external prestressing reinforcement technology is often used to reinforce the portal frame. In this paper, a new type of assembled anchoring joint was designed to connect the steel strand to the steel beam of a portal frame without damaging the original structure. The static loading test was performed by adjusting length of the strut. And the changes of strain and mid-span deflection were investigated. The Midas Gen FEM simulation was used to investigate stress characteristics of the reinforced portal frame, including strain, bending moment, shear force, etc. The experimental results and simulation results were compared to verify effectiveness of the designed joint. The results indicated the new prestressed anchoring joints had the advantages of simple structure, effectiveness, and force transfer path of the joints was clear. Therefore, the new prestressed anchoring joint can be applied to the external prestressing reinforcement of the portal frame. [ABSTRACT FROM AUTHOR]

In this study, straight composite steel-concrete beams were tested to investigate their mechanical performance under combined negative bending and torsional moments. Two specimens were used in this study, and different ratios between the applied negative bending and torsional moments were induced. Load and deflection relationships, strain development on the steel main girder and shear connectors (stud), and the slip development on the steel-concrete interface were recorded in the test and reported in this paper. The results indicate that increase of torsional moment will result in the significant decrease of the load-carrying capacities (e.g. yield load and ultimate load) of the specimens. It was also found that the normal strains of stud shear connectors in such beams are very large and non-negligible compared to their shear strains. In addition, the maximum interface slip was found occurring at around the 1/4 span, and the support conditions and serious crack of the concrete were considered to be the main causes. The research results obtained in this study can provide references for the design and analysis of steel-concrete composite beams subjected to the combined negative bending and torsional moments. [ABSTRACT FROM AUTHOR]

The mechanical performance of concrete connection plays an important role in the response of precast concrete structures. Unlike conventional small concrete shear key which is mainly to help with alignment at installation, large concrete shear keys have been often designed in recent engineering practice to improve joint shear resistance. However, the mechanical properties of large concrete shear keys have not been properly studied. This paper utilizes experimental and numerical methods to investigate both direct shear and flexural bending properties of shear keys. Four types of shear keys comprised of trapezoidal shape, semi-spherical shape, dome shape and wave shape are investigated, which are found to strongly influence the mechanical properties of the keyed joint. Laboratory shear test found unlike conventional shear key, with increased tenon size failure moves to concrete mortise. A detailed numerical model is built to help understand stress developed at the key joint. Flexural bending tests are carried out to evaluate the flexural bending properties of these key joints. Through comparing with theoretical derivation for plain flat joint, similar bending moment resistances from the keyed joints are measured with that of plain flat joint, but larger rotation angles are recorded probably because more damages at the key joint. Among the four different joint patterns, shear key with smoothed pattern could effectively relief concrete damages. [ABSTRACT FROM AUTHOR]

Structural units are the basic components of self-locking foldable grid structures, and their spatial configurations have a vital influence on the structural performance of the overall grid. Research on the deployment process of structural units can help effectively control their stress level and achieve a rational self-locking capability for the units. Therefore, this article describes experimental and modeling studies on the deployment process of structural units and provides a reference for the establishment of numerical models and the design of structural units. The experimental results revealed that the self-locking capability of a structural unit is mainly determined by the bending moments of its members in the planes of the scissor-like elements. The method for adjusting the locations of the pivot endpoints at the radial bars is effective for improving the self-locking capacity, but the degree of adjustment must be strictly controlled to prevent large rotation at the inner lower hub joint. In addition, the feasibility of the modeling method was verified by comparing the experimental curves with the curves obtained by theoretical models. [ABSTRACT FROM AUTHOR]

Wind and wave loadings have a predominant role in the design of articulated offshore towers for its successful service and survival. Such towers are very sensitive to the dynamic effect of environmental loads. The compliant nature of these towers with environmental loads introduces geometric nonlinearity due to large displacements, which becomes an important consideration in the analysis of these towers. This article deals with the dynamic response of a bi-articulated offshore tower to wind, wave, and current forces. The exposed portion of the tower is subjected to the action of wind, while the submerged portion is acted upon by random wave and current forces. Wind load is modeled by Ochi and Shin spectrum, while the wave load is characterized by Pierson–Moskowitz spectrum. The nonlinear dynamic equations of motion are derived by Hamilton's principle. Response of the tower is determined by a time domain iterative (Wilson-θ) method. Power spectral density of important parameters such as surge, tilting motion, hinge shear, and bending moment are presented under high and low sea states. It is observed that response of tower due to current modifies the peak energy of power spectral density functions. [ABSTRACT FROM AUTHOR]

To investigate wind-induced torsional loads on rectangular tall buildings, five rigid scale models were tested in an atmospheric boundary layer wind tunnel. Each model was built with identical plan dimensions but different aspect ratios. Two terrain categories were experimentally simulated in the wind tunnel to evaluate each model under different wind directions. From synchronized wind pressure measurements, the values for the shear wind force, bending moment, and torsion moment at the base of each model were calculated. The results were normalized in terms of mean shear, bending, and torque coefficients. Variations of the coefficients obtained with respect to the aspect ratio of the models tested were analyzed. Based on the experimental results, a new parametric equation to estimate the torque coefficients at the base of rectangular tall buildings as a function of aspect ratio and wind direction was proposed. The base torque coefficients obtained with the proposed equation are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This article focuses on the lateral-torsional buckling resistance of girders with slender, class 4 cross-sections with a research aim to check the accuracy of the design resistance model of EN1993-1-1 and EN1993-1-5 on the coupled instability of lateral-torsional buckling and local plate buckling resistances. The current Eurocode-based design method considers in the effective cross-sectional resistance calculation that yield strength is reached in the extreme fibre of the cross-section, and the reduction factor (ρ p) related to local plate buckling is calculated based on this assumption. However, if lateral-torsional buckling occurs, maximum stress in the web can be significantly smaller at the ultimate limit state which is not considered in the effective cross-sectional resistance calculation. On the other side, EN1993-1-1 proposes to consider the effective bending moment resistance in the relative slenderness calculation of lateral-torsional buckling, which is in contradiction with the general definition of the relative slenderness ratio ( λ ¯ LT) , which should refer to the plastic resistance divided by the critical load of the structure. This article aims to check if the current Eurocode-based design rules need improvement and to check the effect of the above-mentioned specific issues on the calculated lateral-torsional buckling resistance. An extensive numerical research programme is executed to check and compare the lateral-torsional buckling resistance of class 3 (as reference) and class 4 cross-sections, and results are compared to Eurocode-based design models. [ABSTRACT FROM AUTHOR]

This article presents an experimental and numerical study on seismic performance of semi-tenon joints reinforced by steel angle in traditional timber buildings. Five specimens with two different reinforced connections and one unreinforced connection subjected to low-cyclic reversed loading on the bending moment are examined. The unreinforced connection consists of left and right beams inserted into the column that has been used in setting up the mortise before assembly. The first type of reinforced connection is formed by bottom steel angles bolted to the column and jointed to the beam by means of bolts. The second type of reinforced connection is made up of top and bottom steel angles bolted to the column and connected to the beam relying on vertical and transverse bolts. Moreover, two reinforcement techniques aimed at enhancing the seismic performance of semi-tenon joints are investigated, including the change of steel angle limb length and the variation of steel angle limb thickness. The test setup, joint connection, reinforced conditions, and material properties are introduced through detailed account of the experimental results and observations. The key behavioral patterns are identified from the experiments and the main response characteristics such as hysteresis, stiffness, flexural capacity, energy dissipation, and the failure mechanism. This article demonstrates that the steel angle can enhance the flexural capacity of the semi-tenon joints significantly. Besides, the use of greater limb thickness steel angle is shown to be an effective detail for adequately increasing the flexural capacity and rotation stiffness of the joints. Finite element simulations of experiments are also conducted, together with a detailed description of the modeling methods, so as to gain further insight into the influence of various factors on the behavior of joints. [ABSTRACT FROM AUTHOR]

This article presents a study on the impact of the screw location and the diaphragm effects on the buckling behavior of the simply supported C/Z-section purlins under wind uplift loadings. The diaphragm effects provided by the sheeting and the warping-torsional effect induced by load eccentricity are taken into account in the differential equations of the nonlinear twisting flexural-torsional model. The biaxial bending moments, bi-moments, as well as the flexural-torsional buckling load of the purlin can be numerically obtained with the proposed model. The global, local, and distortional buckling interaction behavior and the limit states capacities are formulated based on the modified Direct Strength Method. The effects of both the restraints provided by the sheeting and impact of the screw location on the mechanical performance of the purlins are evaluated with the proposed method. The relationship between the buckling load and rotational restraint stiffness is also provided. The proposed methodology will contribute to the assessment of buckling capacity of purlin-sheeting systems. [ABSTRACT FROM AUTHOR]

During the construction of suspension bridges, the stress state of the pylon (tower) is improved by pushing the pylon saddle by an appropriate distance at the proper time. An analytical algorithm for the assessment of the required timing and displacements for the pylon saddle pushing at particular construction stages is proposed and verified in this study. The timing calculation is based on the assessment of current hanger tensile forces at each construction stage and the pylon stress state, while the pushing distance/displacement is derived from the conditions of elevation difference closure and the conservation of unstrained length of the main cable segments. This algorithm was successfully applied during the construction of a particular suspension bridge in China with a main span of 730 m. The results obtained strongly indicate that the bending moment in the pylon bottom is contributed by both horizontal and vertical forces of the main cable. The horizontal constituent is dominant and its share gradually increases in the bridge construction process. In a suspension bridge with side spans of various lengths, the stresses in the pylon bottom on the side with a larger side span is more likely to exceed the limit. Therefore, the respective strength criterion controls the pylon saddle-pushing schedule. The proposed analytical algorithm is quite straightforward and is recommended for wider application. [ABSTRACT FROM AUTHOR]

This study aims to investigate the strength reduction effect of chord axial stresses on the static strength of cracked tubular T/Y-joints under out-of-plane or in-plane bending moment using finite element analyses. The cracked tubular T/Y-joints contain a semi-elliptical surface crack at the weld toe of the chord. The benchmark analysis compares the numerically computed load–deformation response of a cracked X-joint fabricated from high-strength steel reported in a recent experimental study. This investigation quantifies the strength reduction caused by the chord axial stresses using the chord stress function Qcf. The parametric study covers the effect caused by the variation in both the local crack geometries, that is, the crack area and the global joint dimensions on the computed chord stress function. Finally, we give recommendations to calculate the strength reduction of the investigated cracked joints due to the chord axial stresses. [ABSTRACT FROM AUTHOR]

The scale of fluctuation (θ) of the material and geometrical parameters is the basis of studying the spatial variability of reinforced concrete structures. In this article, a new estimation method for the scale of fluctuation based on Bayesian information criterion is proposed. And based on the analysis of experimental data recorded on the three 36-year-old beams of the Jianggong Bridge and 246 corroded steel bars, the scale of fluctuation (θ) of concrete compressive strength (fc) and steel pitting factor (R) are estimated. The theoretical bending moment of three test beams are calculated considering the influence of the spatial distributions of fc, R, and other relative variables. The reasonableness and superiority of the Bayesian information criterion model than the auto-correlation function method and the semivariogram function model are verified by comparing the theoretical results with the measured bending moment of the three beams mentioned above. [ABSTRACT FROM AUTHOR]

Based on realistic modeling of 44 bridges in national bridge inventory using its actual layout and dimensions, a theoretical framework is defined to calculate the tolerable differential settlement limits based on the over-bending moment or over-shear force generated by settlements and the moment or shear capacity of the bridge. First, the derived over-bending moment or over-shear force is validated through literature results. Second, the differential settlement limits of bridges are derived from the bridge strength capacities. Finally, based on the established differential settlement limits, the relationship of bridge differential settlement limits with its span length, number of spans, bridge skew, and the bridge type is discussed and compared with American Association of State Highway and Transportation Officials specification (2010). A statistics-based differential settlement limit criterion is also suggested for steel and pre-stressed concrete bridges and compared with the field survey results. From the research outcomes, it is concluded that extra caution is needed when implementing the 0.4% differential settlement limits of bridge foundations in American Association of State Highway and Transportation Officials. [ABSTRACT FROM AUTHOR]

Dynamic load allowance (DLA) is an important index used in design and evaluation of dynamic performance of highway bridges to moving vehicular loads. In many codes, DLAs of different responses in various sections are not distinguished. To facilitate a rational design and objective evaluation, the quantitative relationships of DLAs corresponding to different responses in various sections are systematically studied using both theoretical derivation and numerical simulation. According to results of theoretical derivation, for simply supported girder bridges, DLA of deflection is almost 20% higher than that of bending moment in the mid-span section. According to results of numerical simulation, for continuous girder bridges, DLA of negative (upward) deflection is 20% higher than that of positive deflection, and DLA of negative bending moment is 40% higher than that of positive bending moment in critical cases. These significant differences cannot be ignored. Finally, the contributions of high modes to different dynamic responses in various sections are investigated. Based on the recommended approach to considering these differences, the dynamic performance of bridge can be designed and evaluated in a simple yet rotational way. [ABSTRACT FROM AUTHOR]

One component-based mechanical model is presented in this paper to predict the flexural strength of through-diaphragm connections between concrete- filled RHS columns and H-beams. Three parts are contributed to the overall flexural strength of the connections: the failure of the through-diaphragm, the bending action of the column tube, and the tensile membrane action of the column tube. The component-based strength model is based upon defining a rigid plate deformation pattern for the connection under bending moment and then applying the virtual work principle. The proposed model is capable of predicting the ultimate flexural strength of the connections. The developed model is validated against a series of experiments with varied dimensions of column tubes and diaphragms. The results showed that the derived strength equation provided a reasonable prediction. [ABSTRACT FROM AUTHOR]