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In this paper, a leaky-wave antenna based on substrate integrated waveguide is introduced with continuous beam scanning from backward-to-forward through broadside. A new two-part unit cell has been used to achieve the continuous beam without drop of gain in the broadside. This suppresses the open stop-band, the broadside radiation gain would be without a drop, and the side lobe level is kept low. The wide operating bandwidth is obtained, which covers from 11.7 to 19.6 GHz. It is observed that S11 is below − 10 dB from 11.5 to 20 GHz, and the average S21 is − 8.5 dB from 11.5 to 20 GHz. Scanning of this antenna is continuous and covers all angles between − 61° to + 34°. The gain in the direction of the broadside beam is equal to 14.2 dB and without a drop. The gain changes are low in the operating frequency and the average gain is 14.1 dB in this antenna, also the average side lobe level is − 12 dB. The average radiation efficiency of this proposed antenna is 73%.

This study investigates the seismic performance of potential plastic hinge regions in small and medium-sized bridges using Engineered Cementitious Composite (ECC) concrete. A 4×40m continuous beam bridge is used as an example, with time-history analysis conducted using the OpenSees finite element software, and the type of concrete material in the cross-section of the bridge pier’s plastic hinge region is varied to analyze the structural natural vibration characteristics and seismic responses of the bridge structure under earthquake action. The time-history analysis of seismic motion shows that after replacing the bridge pier’s plastic hinge region with ECC, the stiffness of the bridge pier significantly decreases, and the natural vibration period of the bridge increases. Under the action of longitudinal earthquakes, the energy dissipation capacity and seismic performance of the bridge pier increase with the increase in ECC content in the plastic hinge region at the bottom of the bridge pier. Furthermore, under earthquake action, the concrete at the edge of the cross-section using ordinary concrete throughout cracks under tension, while the tensile stress in the cross-sections using different proportions of ECC concrete remains the same and does not crack under tension, remaining elastic under compression, which also reflects the good seismic performance of ECC concrete.

Although continuous beams may be found in a range of projects such as garages, bridges, and multi-story structures, studies have been still restricted to a limited field. Flexural cracks are a common issue in continuous beams; therefore, this article outlines an investigation study used to assess the performance of two-span reinforced concrete beams repaired by attaching (CFRP) sheets. The program included seven beam specimens with a length of 2800mm and rectangular cross sections of 150*250mm. All beams were strengthened externally on the tension zones via CFRP-sheet considering changing the ratio of sheet length to beam span which is 0.5, 0.7, and 0.9 except one was chosen as a reference beam. Repaired beams were preloaded with damage ratios of 45% and 65% with respect to the reference beam. The findings showed that using style 0.7L for both positive and negative regions achieve an appropriate restored percentage of ultimate capacity of about 101.7% and 98.2%. In addition, eliminating the sheet length in the positive moment regions gives higher stiffness. it is also found that when the CFRP sheet length in the tension part is increased, the tensile rupture of the sheet was the dominant failure mode.

In this paper, A high-order response surface method is proposed for finite element model updating of continuous beam bridges. Firstly, based on visual inspection and environmental vibration testing, the peak picking (PP) method and random subspace identification (SSI) method are used to identify the dynamic characteristic parameters of the structure. Then, the finite element model of the continuous beam bridge is updated based on the third-order response surface method. It can be concluded that the results of the updated finite element model are in good agreement with the test results, and the maximum error between the calculated and measured frequency is less than 3%, with MAC values greater than 85%. Moreover, the updated finite element model can reflect the current situation of real bridges and serve as the basis for bridge health monitoring, damage detection, and safety assessment.

In this paper, four feasible closing schemes are proposed, three of which are optimization schemes, and the deformation and internal force of the main beam are taken as the control elements, and the closing conditions, cumulative vertical displacement, lower and lower edge stress on the cross-section and horizontal displacement of the support are compared and analysed under different closure sequence schemes. It is found that the displacement and stress differences are large in different closure sequence schemes, different structural system conversion timings, and it is necessary to carry out optimization studies and comprehensively compare and select reasonable schemes. The construction control of the closure stage is studied, and the results of bridge construction control are compared, which shows that the optimization technology and construction control technology of the closure sequence can be used in this paper, which can solve the key problems in the construction control of the closure of long-link continuous beam bridges, and can provide reference and basis for the construction control of the same type of bridge.

A novel substrate integrated waveguide (SIW) adopting a leaky-wave antenna (LWA) for continuous beam scanning for tri bands is presented. For continuous beam scanning (CBS), optimization of different parameters associated with the unit cell has been carried out. Apart from this, optimal impedance matching is also obtained with the help of the characteristic impedance of the waveguide. The proposed SIW LWA scans from −58° to + 59° along with 14.50 dBi gain when the frequency changes from 10 GHz to 18.22 GHz and provides a scanning rate of 14.23. The beauty of the suggested antenna is its smaller size and high gain, along with a wider scanning range (117°) capability. This antenna’s final prototype has been fabricated, and the measurement results are matched with the simulation results.

Traditional glulam beam connection mode has a weak ability to transfer bending moment, leading to insufficient joint stiffness and mostly in the form of simply supported beams. To make full use of material strength, a novel prestressed glulam continuous beam was proposed. On this basis, this paper put forward a new method to further improve the mechanical performance of the beams by controlling prestress. According to the estimated ultimate loads of the beams, six different control range values were formulated, and 12 continuous beams were tested for flexural performance. The effects of prestressing control on the failure modes, ultimate load capacity, and load versus deformation relationships of the glulam continuous beams were analyzed. The test results indicated that the flexural performance of the beams with prestressed control was significantly improved compared to the uncontrolled beams, the ultimate load was enhanced by 13.60%–45.11%, and the average steel wire stress at failure was increased from 70% of the designed tensile strength to 94%. Combined with the finite element analysis (FEA), the reasonable control range of the prestressed control continuous beams was18%–30% of the estimated ultimate load. The research in this paper can provide references for the theoretical analysis and engineering application of similar structures.

The objective of this research is to comprehensively investigate the vibration response of multi-span beams with unequal spans under moving loads and propose an efficient approach for obtaining the maximum acceleration with fewer calculations. To decrease the volume of computations, apart from employing analytical solution of the bridge motion equation, an efficient approach for determining the crucial trains is adopted. To do so, the governing equation is obtained and solved analytically using Duhamel integral method. To examine the solution, the results are compared with those of the Newmark Beta method and finite element method. Then, the vertical accelerations of the beam caused by equidistant loads are calculated, and their maximum values are determined. The results show that for finding the maximum acceleration, it is enough to calculate the responses for the first two modes at resonant speeds. After that, the beam responses under ten high-speed trains are computed, and the challenging conditions are determined. Finally, the accelerations due to trains and equidistant loads are compared, and a good correlation is observed between the results of two loadings. Therefore, it is possible to distinguish the challenging trains and their critical conditions using the former results and without calculating the vibrations caused by trains. This method enables the designers to concentrate on the most critical loading cases and can be applied in designing or upgrading railway bridges.

Prestressed concrete (PC) continuous beam bridges are widely used in transportation infrastructure. However, their construction involves substantial material consumption, raising sustainability concerns amid increasing environmental pressures. This study aims to address the urgent need for resource-efficient bridge design by developing a comprehensive optimization framework that minimizes material usage while ensuring structural safety, durability, and compliance with engineering standards. The proposed methodology integrates a Genetic Algorithm (GA) with a Backpropagation (BP) neural network to optimize both the cross-sectional geometry and the overall alignment of PC continuous beam bridges. The GA is utilized to identify optimal cross-sectional parameters within regulatory constraints, while the BP neural network, trained on extensive design data, refines the bridge bottom height profile to enhance structural performance. The integrated GA-BP framework is validated through a case study of a continuous beam bridge, demonstrating a 94% improvement in design efficiency, a 14% reduction in concrete consumption, and a 34% reduction in prestressed steel usage during the preliminary design stage. These results highlight the framework’s significant potential in advancing sustainable and intelligent bridge design, offering a novel approach to combining artificial intelligence with structural optimization for practical engineering applications.

Despite the widespread use of RC continuous beams, the performance of these beams, when repaired via Fiber Reinforced Polymer (FRP) composite material, has received less attention. Furthermore, several features of the flexural aspect of repaired RC continuous beams still demand experimental and analytical evaluation. However, many anchoring methods have been developed to delay premature failure in the RC beams, which are strengthened with FRP composite materials. The plan of this experimental study consists of eight continuous beams cast with dimensions (150*250*2800) mm considering the length of the clear span is 1300mm. Except for one, all specimens were attached via Carbon FRP sheets about 70% of the span length in negative and positive moment zones beyond a predetermined damage level. Moreover, this study suggested modifying the end-anchor technique and adding CFRP layers with (45, 65, and 95) % as damage ratios. According to the results, the optimal percentage of restored ultimate capacity was 108.8% with peeling-off concrete cover failure mode, which was obtained from using an end-anchor and two layers of the sheet. Also, increasing the damage ratio leads to a decline in toughness and ductility values. In addition, it is possible to repair the structure with a 95% damage ratio rather than remove it.