Long-span Steel Research Articles

Construction Technology of Warm and Hot Mix Epoxy Asphalt Paving for Long-Span Steel Bridge

AbstractEpoxy asphalt concrete (EAC) is widely used in long-span steel bridge paving due to its good performance. It can be classified into two types of materials based on its construction temperat...

Structure-borne noise from long-span steel truss cable-stayed bridge under damping pad floating slab: Experimental and numerical analysis

This study investigates the structure-borne noise characteristics and a control measure of the long-span steel truss cable-stayed bridge (LSTCB) which are induced by running trains in urban rail transit. A frequency-domain theoretical model of a vehicle–track coupling interaction system, in which the vibration reduction track structure of damping pad floating slab (DPFS) are taken into account, is firstly established, from which the wheel–rail dynamic force, the force transmission rate, and the force transmitted to the bridge can be obtained. After that, a vibration model of the LSTCB and a noise model of the steel truss girder are established, which are based on the refined finite element method (FEM) and statistical energy analysis (SEA) method respectively, to predict the structure-borne noise of the LSTCB. Next, the near-field noise test of an LSTCB under DPFS at an urban rail transit line, are analyzed and used to validate the prediction model. Then, the structure-borne noise characteristics of the LSTCB and noise reduction effect of DPFS are studied. It is found that the wheel-rail transfer to the track slab and bridge are influenced by the track structure system; the attenuation rate of the near-field sound pressure level (SPL) is relatively slow in the range of 20–100 Hz, fast after 100 Hz, and faster than the far-field SPL; the vibration energies that input to the LSTCB are mainly distributed in the bridge deck, longitudinal web, and transverse web; the sound radiation capability of the bridge deck is stronger than that of other subsystems; compared with the common track structure (embedded sleeper), the track structure of DPFS can reduce the overall sound pressure level of the LSTCB by 10–13 dB(A).

Thermal Effect on Rheological Properties of Epoxy Asphalt Mixture and Stress Prediction for Bridge Deck Paving

AbstractEpoxy asphalt mixture has been widely used as an excellent paving material on long-span steel bridges; however, low-temperature cracking is a significant concern for paving on an orthotropi...

Lift monitoring and analysis of multi-storey corridors in buildings

Based on the steel corridor of the first-stage construction for Panzhihua City Government Service Centre, this paper introduces the integral lifting scheme of multi-storey long-span beam grillage steel corridor. To ensure the safety and stability in the lifting process of steel corridor construction and to prevent sudden overload from affecting the later normal use, the finite element simulation of steel corridor before lifting and real-time monitoring during the lifting process were carried out. The results of finite element simulation were compared with the stress and deflection data monitored in real time. It shows that the numerical data obtained from the finite element methods (FEM) are slightly larger than those from the actual monitoring. It follows that the results obtained from FEM for the lifting is safer, the data obtained from FEM and monitoring agree with each other, and, accordingly, the study shows that the monitoring approach is applicable. The integral lifting scheme and monitoring approach presented here can be used as an interesting reference for similar projects. • The integral lifting scheme of multi-storey beam grillage steel corridor is reasonable. • The method of monitoring stress and deflection data is simple and practical. • The remote monitoring system ensures the safety of the monitors. • Deflection monitoring device is a new inventive device. • The monitoring data are in good agreement with the finite element simulation data.

Automatic Identification of Bridge Vortex-Induced Vibration Using Random Decrement Method

Vortex-induced vibration (VIV) has been occasionally observed on a few long-span steel box-girder suspension bridges. The underlying mechanism of VIV is very complicated and reliable theoretical methods for prediction of VIV have not been established yet. Structural health monitoring (SHM) technology can provide a large amount of data for further understanding of VIV. Automatic identification of VIV events from massive, continuous long-term monitoring data is a non-trivial task. In this study, a method based on the random decrement technique (RDT) is proposed to identify the VIV response automatically from the massive acceleration response without manual intervention. The raw acceleration data is first processed by RDT and it is found that the RDT-processed data show different characteristics for the VIV response and conventional random response. A threshold based on the coefficient of variation (COV) of peak values of processed data is defined to distinguish between the two kinds of responses. Both random vibration and VIV for a three-DOF (degree-of-freedom) mass-spring-damper system are obtained by numerical simulation to verify the proposed method. The method is finally applied to the Xihoumen suspension bridge for identifying VIV response from three-month monitoring data. It is shown that the proposed method performs comparably with the method of novelty detection. A total of 60 VIV events have been successfully identified. Vortex-induced vibrations for the second to ninth vertical modes with modal frequency within 0.1~0.5 Hz occurs at wind velocity 5–18 m/s, with wind direction nearly perpendicular to bridge axis. Amplitude of VIV generally decreases with increase of wind turbulence intensity; however, noticeable VIV amplitude are still observed for turbulence intensity up to 13% in some cases.

Analysis of Viscoelastic Mechanical Response of Asphalt Mixture Pavement on Steel Deck under Imperfect Contact Conditions

Abstract For long-span steel bridges, the contact states between the pavement and the steel decks change significantly during the operation stage. Different interlayer contact states have different effects on the viscoelastic mechanical properties of the pavement. Here, the modified SMA10 mixture and the epoxy–asphalt mixture are compared in terms of the transverse tensile strain, the transverse tensile stress, and the deflection at the bottom of the asphalt layer under different contact conditions. The main curve clusters of the relaxation modulus were obtained using the creep test data, and the effects of four different contact conditions on the viscoelastic mechanical response of the asphalt mixture pavement of the Huangpu Suspension Bridge in China were analyzed accordingly. It was found that the delayed deformation capacity of the epoxy–asphalt mixture is better than that of the modified SMA10 mixture. The change of the interlayer contact condition has an impact on the viscoelastic mechanical response of the asphalt mixture pavement; for the modified SMA10 asphalt mixture pavement, the transverse tensile stress and the transverse tensile strain at the bottom of the pavement are more sensitive to the contact condition than the deflection. For the epoxy–asphalt mixture pavement, the deflection is more sensitive to the contact condition.

Vibration characteristics of damping pad floating slab on the long-span steel truss cable-stayed bridge in urban rail transit

With the development of urban rail transit, long-span steel truss cable-stayed bridges have become increasingly favored. Therefore, train-induced bridge-borne vibration and noise are occurring more often. The damping pad floating slab (DPFS) has been widely used as an effective vibration damping track structure; however, there is a lack of research on the vibration mechanism and effects of the DPFS for long-span steel truss cable-stayed bridges. This study focuses on the steel truss cable-stayed bridge in urban rail transit. First, the theoretical model of the train-track-bridge coupling interaction is established in the frequency-domain (the track structure is DPFS, and the interaction of multiple wheels is considered). Using this model, the wheel–rail dynamic force, force transmission rate of the track, and the force transmitted to the bridge are calculated. Then, the vibration prediction model of the long-span steel truss cable-stayed bridge is established using the plate-beam finite element (FE) method and statistical energy method. The force transmitted to the bridge is applied to the vibration prediction model to obtain the vibration transmission characteristics of the typical plate of the bridge. The prediction model is verified by comparing the obtained results with the field test of a long-span steel truss cable-stayed bridge, and the damping mechanism of DPFS track is discussed. Finally, the force transmitted to the bridge is calculated based on the embedded-sleeper (ES) track structure (the ES has no vibration damping facilities). The values of the overall vibration level are calculated from the prediction models using ES and DPFS, and the vibration reduction effect of DPFS is studied by comparison with the ES.

Study on the safety of the concrete pouring process for the main truss arch structure in a long-span concrete-filled steel tube arch bridge

To study the safety and stability of the main truss arch structure during the concrete pouring process in a long-span CFST arch bridge, a combination of theoretical analysis and numerical simulation was adopted. The world's longest span CFST arch bridge, the Pingnan Third Bridge (main span 575 m) in Guangxi Province, was taken as an example. Firstly, the basic theory of stability and the concrete pouring technology of the main truss arch structure were summarized. Secondly, a three-dimensional finite element model of the main truss arch structure was established for the concrete pouring stage. Finally, the linearity, stress, and stability of the main truss arch structure during concrete pouring were studied. The results show that both vertical and transverse deflections occurred in the main truss arch structure during concrete pouring from the arch foot to the arch vault; the upper and transverse deflections of the main truss arch structure showed parabolic changes, and the upper and transverse deflections of the midspan section were larger than those of other sections. When concrete was poured near the 1/6 section of the main truss arch structure, the upper and transverse deflections of the middle section of the main truss arch structure peaked; the maximum upper deflection reached 113 mm, and the maximum transverse deflection reached 60 mm. In the process of concrete pouring from the arch foot to the arch vault, the stress in the steel tubes and concrete was constantly changing. Although upper and transverse deflections of the main truss arch structure occurred during concrete pouring, the stress in the steel tube and concrete in the main truss arch structure did not exceed the tensile strength, and the linearity of the main truss arch could be adjusted by retaining the anchor cables, which were set in the erection stage of the main truss arch structure at the 1/6 section of the main truss arch structure. During the concrete pouring process of the various steel tubes of the main truss arch structure, the stability coefficients of the main truss arch structures decreased gradually. During concrete pouring in a single steel tube, the maximum reduction in the stability factor was 21.32%, which occurred in the 1# steel tube, and the minimum decrease in the stability factor was 8.89%, which occurred in the 8# steel tube. The stability coefficients were greater than 4 after this reduction and met the requirements of the design specifications. This study can provide a reference for the optimization design and construction monitoring of long-span CFST arch bridges.

Experimental Study on Force Bearing of Long Span Wide Steel Box Girder Cable-Stayed Bridge in Construction Stage

In the design and construction of long-span steel box girder cable-stayed bridges, shear lag is often an important factor affecting the stress of bridge structures. A certain waterway super large bridge is a wide-section steel box girder cable-stayed bridge, which adopts cantilever assembly construction to study the influence law of the current section and the current section working condition on the shear lag effect of the completed beam section tested. The results show that The stress is constantly changing as the construction phase changes. On the whole, the stresses at different positions of each section are increasing. From 11:00 to 15:00, the stresses at each measuring point of the beam increase, including the compressive stress at the top of the beam and the tensile stress at the bottom of the beam.

Verification of pushover analysis for a long-span steel truss structure

Pushover analysis has become an effective tool for seismic design of high-rise buildings under severe earthquakes. However, the applicability of traditional pushover analysis is often questioned for long-span structures due to their complex dynamic characteristics. In this paper, pushover analysis was adopted to determine the seismic behavior of a long-span steel truss structure under severe earthquakes. Load distributions were determined based on the fundamental modes for vertical and horizontal earthquakes respectively. Pushover curves were obtained by nonlinear static analysis. Target displacements were determined with capacity spectrum method. The maximum displacements and plastic hinge distributions determined by traditional pushover analysis agreed well with those by nonlinear time history analysis for both horizontal and vertical earthquake actions. It was then concluded that the seismic behavior of this kind of long-span steel truss structures can be evaluated by traditional pushover analysis accurately enough for practical design purpose.

Dynamic Parameter Identification of a Long-Span Arch Bridge Based on GNSS-RTK Combined with CEEMDAN-WP Analysis

Under the action of wind, traffic, and other influences, long-span bridges are prone to large deformation, resulting in instability and even destruction. To investigate the dynamic characteristics of a long-span concrete-filled steel tubular arch bridge, we chose a global navigation satellite systems-real-time kinematic (GNSS-RTK) to monitor its vibration responses under ambient excitation. A novel approach, the use of complete ensemble empirical mode decomposition with adaptive noise combined with wavelet packet (CEEMDAN-WP) is proposed in this study to increase the accuracy of the signal collected by GNSS-RTK. Fast Fourier transform (FFT) and random decrement technique (RDT) were adopted to calculate structural modal parameters. To verify the combined denoising and modal parameter identification methods proposed in this paper, we established the structural finite element model (FEM) for comparison. Through simulation and comparison, we were able to draw the following conclusions. (1) GNSS-RTK can be used to monitor the dynamic response of long-span bridges under ambient excitation; (2) the CEEMDAN-WP is an efficient method used for the noise reduction of GNSS-RTK signals; (3) after signal filtering and noise reduction, structural modal parameters are successfully derived through RDT and illustrated graphically; and (4) the first-order natural frequency identified by field measurement is slightly higher than the FEM in this work, which may have been caused by bridge damage or the inadequate accuracy of the finite element model.

Checking Calculation Analysis for Construction of Long-span Steel Box Girder Bridges

With the rapid development of China’s society and the implementation of the Belt and Road policy in recent years, many large-scale complex steel structure bridges are constructed, typically represented by the Hangzhou Bay Sea-Crossing Bridge and the Hong Kong-Zhuhai-Macao Bridge. In this paper, the checking calculation for the overall force of the steel box girder during construction is studied. The analysis shows that the steel box girder concerned has good stiffness and ductility.

Experimental and numerical study of connection effects in long-span cold-formed steel double channel portal frames

Cold-formed steel haunched portal frames are popular structures in industrial and residential sectors. They are commonly used in rural areas for sheds, garages, and shelters, and are now being constructed with spans of up to 30 m in Australia. As these large structures are relatively new to the market, there is limited data on their behavior and design recommendations, including connection stiffness and design. Numerical and experimental parametric studies were conducted on a haunched portal frame composed of back-to-back lipped channel sections bolted through the webs for the main frame members, and back-to-back L-brackets bolted though the webs at the connections. An advanced shell finite element model was created and validated with experimental results to confirm the suitability of the modeling technique. The validated finite element model was then used for parametric studies to determine the effects of various components of the frame, including column base connection stiffness and modifications to the knee brace-to-column connection design, on the frame capacity and behavior. An experimental program was conducted to quantify column base connection stiffness where the connection was comprised of L-brackets bolted through the column flanges at the base. Stiffness was quantified for bending about the column major and minor axes for various thickness L-brackets and for a U-bracket. Apex in-plane connection stiffness was quantified experimentally for several rafter channel thicknesses and depths. Discussions of the results of the parametric studies are presented in addition to the resulting design recommendations for constructing effective long-span cold-formed steel portal frames.

Dynamic stress analysis for fatigue damage prognosis of long-span bridges

For fatigue damage prognosis of a long-span steel bridge, the dynamic stress analysis of critical structural components of the bridge under the future dynamic vehicle loading is essential. This paper thus presents a framework of dynamic stress analysis for fatigue damage prognosis of long-span steel bridges under the future dynamic vehicle loading. The multi-scale finite element (FE) model of the bridge is first developed using shell/plate elements to simulate the critical structural components (local models) and using beam/truss elements to simulate the rest part of the bridge (global model). With the appropriate coupling of the global and local models, the multi-scale FE model can accurately capture simultaneously not only the global behavior in terms of displacement and acceleration but also the local behavior in terms of stress and strain. A vehicle traffic load model is then developed for forecasting the future vehicle loading based on the recorded weigh-in-motion (WIM) data and using the agent-based traffic flow microsimulation. The forecasted future vehicle loading is finally applied on the multi-scale model of a real long-span cable-stayed bridge for dynamic stress analysis and fatigue damage prognosis. The obtained results show that the proposed framework is effective and accurate for dynamic stress analysis and fatigue damage prognosis.

Multi-scale fatigue damage prognosis for long-span steel bridges under vehicle loading

Fatigue damage prognosis for long-span steel bridges is of the utmost importance in bridge maintenance and management. In this study, a multi-scale fatigue damage prognosis algorithm is developed to calculate the trans-scale fatigue damage accumulation of newly-built long-span steel bridges under vehicle loading. The necessity and procedure of establishing a multi-scale finite element (FE) model of a newly-built long-span bridge for fatigue damage prognosis are first introduced. The future vehicle loading on the bridge is forecasted using the recorded weigh-in-motion (WIM) data and the agent-based traffic flow micro-simulation method. Then, the multi-scale fatigue damage prognosis algorithm is developed based on the multi-scale FE model and using the future vehicle loading. Finally, the proposed algorithm is applied to a newly-built long-span cable-stayed bridge for the time period from 2010 to 2020. The results show that the macro-scale fatigue damage accumulation and micro-scale short crack evolution of the critical components of the bridge can be simultaneously predicted and visualized. The proposed algorithm can be used as a numerical tool for fatigue damage prognosis of steel bridges where (or near where) WIM station is installed.

Evaluation and optimization of bridge deck waterproof bonding system using multi-objective grey target decision method

Surfacing of steel decks is one of the crucial issues which engineers are facing during construction of long-span steel bridges. This study aims to optimise the overall performance of the bridge deck waterproof bonding system. The waterproof bonding system used in this study consisted of two layers, a waterproof layer and a bonding layer. The role of the bonding is to ensure that the deck pavement and the steel panel can form a monolithic structure. The waterproof layer mainly prevents moisture from penetrating into the bridge deck. A series of laboratory experiments were conducted to evaluate the bonding performance of the waterproof adhesive system. Different types of waterproof adhesive systems were considered in the experimental design. Five performance indicators such as tensile strength, direct shear strength, skew shear strength, fatigue life, and project cost, were incorporated for evaluation. Then, the multi-objective grey target decision approach was employed as an optimised method to recommend a suitable waterproof adhesive system. Results showed that the temperature and performance indicators had a significant influence on the ranking of varying waterproof bonding system types. Findings of this research could provide the technical support for the future design of bridge deck waterproof adhesive systems.

Experimental investigation of long-span cold-formed steel double channel portal frames

Cold-formed steel haunched portal frames are popular structures in industrial and housing applications. They are mostly used as sheds, garages, and shelters, and are common in rural areas. Cold-formed steel portal frames with spans of up to 30 m (100 ft) are now being constructed in Australia. As these large structures are fairly new to the market, there is limited data on their behavior and design recommendations. An experimental program was carried out on a series of portal frame systems composed of back-to-back lipped channels for the columns, rafters, and knee braces. The system consisted of three frames connected in parallel with purlins to simulate a free standing structure, with a span of 14 m (46 ft), column height of 5.3 m (17 ft), and apex height of 7 m (23 ft). Several configurations were tested including variations in the knee connection, sleeve stiffeners in the columns and rafters, and loading of either gravity only or combined horizontal and gravity loads. Deflections were recorded at various locations to measure global and local movements of the structural members. A total of eight frames with unbraced columns were tested and one frame with braced columns. Experimental results are presented herein including frame strengths and failure modes for the various frame configurations and loading conditions, as well as quantified moment-rotation relations for the column base connection. The contributions and effects of the different knee connections and sleeve stiffeners are presented. The overall frame behavior of these structures and suggested design considerations are discussed.

Coupling effects between wind and train transit induced fatigue damage in suspension bridges

Long-span steel suspension bridges develop significant vibrations under the effect of external time-variable loadings because their slenderness. This causes significant stresses variations that could induce fatigue problems in critical components of the bridge. The research outcome presented in this paper includes a fatigue analysis of a long suspension bridge with 3300 meters central suspended span under wind action and train transit. Special focus is made on the counterintuitive interaction effects between train and wind loads in terms of fatigue damage accumulation in the hanger ropes. In fact the coupling of the two actions is shown to have positive effects for some hangers in terms of damage accumulation. Fatigue damage is evaluated using a linear accumulation model (Palmgren-Miner rule), analyses are carried out in time domain by a three-dimensional non-linear finite element model of the bridge. Rational explanation regarding the above-mentioned counterintuitive behavior is given on the basis of the stress time histories obtained for pertinent hangers under the effects of wind and train as acting separately or simultaneously. The interaction between wind and train traffic loads can be critical for a some hanger ropes therefore interaction phenomena within loads should be considered in the design.

Monitored structural behavior of a long span cable-stayed bridge under environmental effects

An accurate numerical analysis of the behavior of long-span cable-stayed bridges under environmental effects is a challenge because of complex, uncertain and varying environmental meteorology. This study aims to investigate in-situ experimental structural behavior of long-span steel cable-stayed bridges under environmental effects such as air temperature and wind using the monitoring data. Nissibi cable-stayed bridge with total length of 610m constructed in the city of Adıyaman, Turkey, in 2015 is chosen for this purpose. Structural behaviors of the main structural elements including deck, towers (pylons) and cables of the selected long span cable-stayed bridge under environmental effects such as air temperature and wind are investigated by using daily monitoring data. The daily variations of cable forces, cable accelerations, pylon accelerations and deck accelerations with air temperature and wind speed are compared using the hottest summer (July 31, 2015) and the coldest winter (January 1, 2016) days data.

Study on vertical vibration control of long-span steel footbridge with tuned mass dampers under pedestrian excitation

This paper aims to study crowd-induced vibration control of long-span steel footbridges with different dynamic characteristics by combining methods of site measurement and numerical simulation. Four kinds of footbridge models with sensitive vertical natural frequencies of easily generating human-bridge resonance under pedestrian loading are designed based on an actual steel footbridge. The numerical models are firstly validated by comparative investigation between the site measurement and the simulation. Detailed study on dynamic responses of the four footbridges with and without controlling systems of tuned mass damper (TMD) and multiple tuned mass damper (MTMD) is then conducted under 13 cases of crowd random excitations, rhythmic running and jumping excitations. Results show that the numerical simulation agrees well with the site measurement data. TMD system is found to be highly efficient in reducing vibration responses only when the excitation frequency is basically consistent with the structural natural frequency, which obviously limits the application of TMD system in footbridges as wider excitation frequency bandwidth is caused by human activities. MTMD system are demonstrated to be with higher vibration absorption robustness appearing predominant and stable capacity of reducing structural vibrations under all the crowd random and rhythmic excitations for the four footbridges.