As for the application of UHPC in bridge engineering, Shao et al. (2020) proposed using short steel bars as a new type of connector for steel-ultrathin UHPC composite bridge decks, and studied the shear performance of the connector through static push-out test and fatigue push-out test. Li et al. (2020e, 2021d) proposed to apply UHPC to the bent cap and carried out model test and finite element simulation in combination with the actual project. The results illustrated that the new fully prefabricated prestressed UHPC bent cap had good deformation capacity and anti-crack behavior. Sturm et al. (2020) conducted four point bending tests on UHPFRC beams with steel tendons and CFRP tendons. The results showed that the beams with CFRP tendons had greater bearing capacity under large deformation, smaller main crack width before yielding, but lower cracking stiffness. Liu et al. (2020j) and Zhang et al. (2020h) studied the mechanical properties of steel-UHPC composite beams in the negative bending moment zone, and the results showed that UHPC could increase the cracking load in the negative bending moment zone, reduce the crack spacing, and inhibit the development of cracks.
In order to avoid complex three-dimension model, researchers put forward with several beam element models and simplified equations to explore the short term and long-term performance of composite girders. One type of new composite beam element is proposed with the coupled multi-axial constitutive relationship and the new stability criterion for materials (Das and Ayoub 2020). One-dimensional finite element model is established by using the higher-order beam theory (Uddin et al. 2020) and time-varying finite element model is formed by using general beam theory to study the effects of concrete creep, shear lag and distortion (Henriques et al. 2020). The theoretical model with 11 degrees of freedom is built, containing two-way slips, the lateral displacement, deflections, the torsion angle and the warping angle (Zhu et al. 2020d). Static analysis method of composite beam based on the collocation method is proposed without the spatial discretization (Lin 2020b). Based on Hamilton method, one type of improved analysis method on the basic frequency of the composite box beam with corrugated steel webs is developed (Feng et al. 2019). Considering bonding, friction, the tangent slip and normal cracks in the interface, refined state of the steel-concrete interface is described by the cohesive zone model (Lin et al. 2019). The sequential linear programming algorithm is used to optimize the finite element model of steel-concrete composite beams with partial interactions (Silva et al. 2020).
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The above research is mainly concentrated on I-shaped composite girders with shear studs. As for other types of composite girders, such as composite box girders with corrugated steel webs, truss composite beams and composite girders with concrete-filled steel tube, there is relatively little research. The elastic shear lag effects of corrugated steel web combined box girder with variable cross-section and the influence of bars is extremely studied (Zhou et al. 2020a). The flexural performance of the composite box girder with the concrete slab at top, trusses at bottom and corrugated webs is studied (Chen et al. 2020g). The torsion performance of composite girders with the concrete slab at top, the steel plate at bottom and corrugated webs (Zhang et al. 2020v). The composite beam with multiple longitudinal and longitudinal joints, containing channel shear connectors and I-shape steel, is studied (Arıkoğlu et al. 2020). The four-point flexure tests of the composite girder with friction-based shear connectors under cyclic loads are conducted to study the effective width, the failure mode and the crack propagation (Suwaed and Karavasilis 2020). The different asynchronous construction technology for composited girders with corrugated webs are explored and compared (He et al. 2020; Wang et al. 2020; Zhou et al. 2020j).
Li et al. (2020) proposed a fatigue performance evaluation method for steel bridges considering the train dynamic effect based on a vehicle-bridge analysis model composed of a 3D vehicle model, multi-scale bridge finite element model including the track system, and a wheel-rail interaction model. Ma et al. (2020) considered the effect of bridge foundation scour on the superstructure, carried out fatigue damage assessment on the welded joints of OSBs, and studied the reliability assessment of the structure according to the fatigue cumulative damage theory. Mashayekhi and Santini-Bell (2020) proposed a fatigue assessment protocol for these complex critical components of steel bridges, using the hotspot stress method and multi-scale finite element model. Yang et al. (2020b) investigated multiaxial fatigue property of key welding details in OSB crossbeam based on the structural stress method, and compared the evaluation results with the evaluation methods recommended by international codes and standards, such as the nominal stress method, hot spot stress method and notch stress method. On this basis, the effects of load modes and characteristic parameters on fatigue performance and failure modes of steel bridge deck are further studied. Zhu et al. (2020) monitored the wheel load stress response at the details with different cutout geometries of the steel bridge deck, and estimated the fatigue life of related structural details according to the AASHTO LRFD specifications. Ji and Chen (2020) verified the applicability of different extrapolation formulas suggested by IIW in hot spot stress analysis, and obtained relatively reliable fatigue performance evaluation results in combination with S-N curve provided by IIW. Yokozeki et al. (2021) made a comparative study on fatigue resistance of U rib, V rib and plate rib with diaphragm cross structural details respectively, and determined the reference points of hot spot stress extraction for cross details of different stiffeners. Liao et al. (2020) carried out high cycle constant amplitude fatigue test and numerical simulation of fatigue crack growth for typical steel bridge cruciform fillet-welded joints, and the results showed that relatively accurate fatigue life evaluation results could be obtained by replacing initial defects with semi-elliptical cracks. Zhang et al. (2020a, b) investigated into fatigue resistance evaluation of the rib-to-deck welded joints based on equivalent structural stress method and strain energy density theory (2020). The results showed that the equivalent structural stress method was suitable for fatigue resistance evaluation of multiple fatigue modes of the rib-to-deck welded joints. On the other hand, fracture mechanics is mainly used to solve the fatigue problems of structures with crack defects, and the study of fatigue crack growth law of steel bridge deck based on fracture mechanics is the most direct and effective means to evaluate the fatigue fragility details. Cui et al. (2021) proposed a multiscale fatigue damage evolution model to assess the fatigue life of steel bridge.
In the aspect of anti-fatigue design methods, Jiang et al. (2020) compared and analyzed the local stress characteristics and equivalent stress amplitude of the traditional U-rib to deck structure detail, the new upsetting treatment of U-rib to deck structure and the new double-side U-rib to deck welding structure. The results showed that the upsetting treatment of U-rib could improve the fatigue resistance of U-rib weld toe and double-side welding could significantly improve the fatigue performance of weld toe and root. Fang et al. (2020) discussed the FEM method which was applicable to notch stress of double-side U-rib to deck welding structure, analyzed the influence of roof thickness and weld size on fatigue resistance and optimized the details of the structure. Pu et al. (2020) designed a full-length segment model with two U-ribs and two V-ribs and carried out fatigue test and research with the steel deck of long-span railway bridge as the research object. Zhang et al. (2020a, b) made a systematic theoretical analysis and experimental studies on the fatigue performance of rib-to-deck and rib-to-diaphragm joints, and compared various long-life structural details with the fatigue performance of steel bridge deck structure. The results showed the dominated fatigue cracking pattern of rib-to-deck joints changed into deck weld toe cracking of innovative double-side welding details from weld root cracking of traditional single-side welding details after introducing innovative double-side rib-to-deck welding joint, and the cumulative fatigue damage of structural details was greatly reduced and the fatigue life was significantly improved.
In the aspect of monitoring and detection of fatigue damage in steel bridge, Chen et al. (2020) used ultrasonic testing method to realize the accurate identification of internal defects of U-rib full penetration fillet weld of steel bridge decks. Sun et al. (2020) proposed an ultrasonic double probe penetration testing method for longitudinal cracks at the rib-to-deck weld joint, and used prefabricated crack specimens to test and verify this detection method. Li et al. (2020) embedded piezoelectric ceramics in the steel-UHPC composite structure and applied excitation to generate ultrasonic wave, and to identify the local damage of the composite structure through ultrasonic signal. Duan et al. (2020) monitored the crack propagation process of steel bridge using acoustic emission sensor, and the results showed that this technology could capture dynamic fatigue crack information. Wang et al. (2020) extracted damaged dispersed signals in guided waves based on the singular value decomposition-based guided wave array signal processing approach. The actual analysis of steel bridge deck showed that the proposed method could successfully extract crack information from the measured signals with low signal-to-noise ratios. Solovyov et al. (2021) studied the blocking effect of steel bridge fatigue cracks on external heat transfer under natural environmental conditions, and the results showed that the passive infrared thermography could detect concealed fatigue cracks in steel bridge. 2ff7e9595c
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