Constant Load Research Articles

Experimental and numerical analysis of instrumented caissons in tropical soil

This paper presents an experimental and numerical study on the behavior of three (3) instrumented caissons in a tropical laterite soil in the Planalto Central, DF, Brazil. The concrete caissons have a shaft diameter of 0.6 m, a bell diameter of 1.2 m and 1.3 m and lengths of 8.9 to 14.4 m. Static load tests were conducted out to investigate the behavior of the caissons. The results of load vs displacement and their interactions with the tropical soil were measured and evaluated using the methodology of Camapum de Carvalho et al. (2008, 2010) and numerical modeling with back-calculation of static load tests in the Plaxis 3D software. The paper presents the analysis of the load transfer lines and the comparison with the proposed methods. The results pointed to a constant load transfer along the shaft, with a significant contribution from the skin friction, developed for a fraction of the displacement necessary for its mobilization. The accuracy of using the Camapum de Carvalho et al. methodology stands out (2008, 2010), identifying the region dominated by skin friction, tip and plasticization of the foundation, confirming the authors’ predictions for a tropical soil in the Distrito Federal/DF, Brazil. The numerical method using the Plaxis 3D software, proves that for the limit test load there was a significant contribution from skin friction, which must be consider in the analysis of the behaviour of caissons.

Investigation on effects of nano-reinforcement on the mechanical properties, fatigue, and microstructural analysis of dissimilar AA6061- Mg AZ31B weld joints

Weld joints have been subject to substantial improvement in mechanical durability and wear resistance in recent years. This research work challenge can be answered by incorporating nano-materials into the weld zone. Mechanical and metallurgical aspects of friction stir welded (FSW) butt joints made of AA6061 aluminum and Mg AZ31B alloys have been examined in this work, both with and without the use of naturally derived biochar nanoparticles. The biochar particle was extracted from rice husk. Throughout the whole weld joint manufacturing process, a tool with a rotational speed of 1400 rpm, a welding speed of 40 mm min−1, and a tapered pin profiled tool were employed. During the joint fabrication process, the constant axial load of 7 kN, plunge depth of 0.2 mm, and constant dwell time of 0.3 s were also maintained. In order to improve the mechanical attributes of the weld joints, different wt% of biochar such as 1%, 2%, and 3%, were applied at the interface region of the weld joints. The experimental results revealed that the percentage of reinforced nano-materials plays a significant effect in improving the weld joint qualities. The testing results of reinforced friction stir-welded joint qualities were compared to those of simple friction stir welded joints made without and with adding the nanoparticles. The best results were obtained when 2 wt% of biochar particles was added to the weld interface region. The presence of biochar nano-particles, in addition to their contribution to increased grain refinement in the weld nugget region, was also seen in the region. It was discovered that the event distribution of particles at the nugget zone significantly enhanced the mechanical and wear resistance qualities of the weld joints that were manufactured. The optical microscope was used to analyze the microstructures in the weld nugget region, and a scanning electron microscope (SEM) was utilized to examine the fracture analysis of the tensile samples. The presence of 2 wt% biochar particles in the weld nugget region resulted in a considerable increase in the mechanical characteristics of the weld connections. The ultimate tensile strength, hardness, and yield strength of the weld nugget results 197 MPa, 173 HV, 163 MPa. Overall, when compared to the qualities of the base material and plain weld joints. The mechanical properties and wear resistance of the weld joints have improved significantly. When biochar particles were used as reinforcement particles during the fabrication phase of the joint, a mechanism for pinning was observed in the weld microstructure.

Fatigue Life Assessment of Corroded AlSi10MgMn Specimens

This study investigates the influence of pre-corrosion damage on the fatigue behavior of AlSi10MgMn high-pressure die-cast specimens, using the statistical distribution of corrosion depths. The analysis is conducted on two different surface conditions: an unmachined rough surface (Ra=5.05μm) and a machined, polished surface (Ra=0.25μm). For the unmachined specimens, the corrosive damage manifests as homogeneously spread localized corrosion, whereas the polished specimens exhibit less uniform but deeper corrosion. The average corrosion depth of the polished specimens is found to be slightly higher (313 μm compared to 267 μm) with a broader depth distribution. Specimens are tested under a constant bending load amplitude in laboratory conditions at a stress ratio of R=0 until fracture. A fracture mechanics-based methodology is developed to assess the remaining fatigue life of corroded specimens, utilizing short and long crack fracture mechanical parameters derived from SENB specimens. This model incorporates a thickness reduction of the critical specimen cross-section based on the corrosion depth distribution and combines it with a small initial crack of the intrinsic defect size (aeff=14μm). Regardless of the surface condition, using the most frequent corrosion depth for thickness reduction provides a good estimate of the long-life fatigue strength, while using the 90th percentile depth allows for a conservative assessment.

In-situ synchrotron high energy X-ray diffraction study on the compressive creep behavior of an extruded Ti-45Al-8Nb-0.2C alloy

Wrought high Nb containing (high Nb-TiAl) alloys are potential materials for low pressure turbine blades in aero-engines. The performance and microstructure evolution under high temperature creep condition is of importance to the service stability of these materials. In this study, the internal strain and FWHM evolution of an extruded TNB-based high Nb-TiAl alloy during compressive creep are characterized by in-situ high energy X-ray diffraction (HEXRD) technique for the first time. The compressive creep test was conducted under a constant load of 300 MPa at 900 °C for 10 h in vacuum. The final creep strain is approximately 1.72 %. The microstructure and phase constitution after creep shows little difference from that before creep. Lattice strain analysis shows that γ phase is plastically deformed while the α2 phase deforms elastically due to the low creep strain. The lattice strain of α2 grains is dependent upon the deformation of surrounding γ grains. Creep induces dynamic recovery, exerting a softening effect. A high number of dislocations are visible in the γ lamellae while almost no dislocations exist within the α2 lamellae. α2 lamellae are partially decomposed and refined via the α2→γ transformation.

Effects of hydrogen on the fretting wear behavior of laser cladded FeCoCrNiMo0.2 high entropy alloy coating

This study investigates laser-cladded high entropy alloy (HEA) coatings on high-speed train axles to enhance wear resistance under specific fretting conditions. Axles in humid and acidic environments absorb hydrogen, leading to accumulation in grain boundaries, which weakens their structure and causes damage under alternating stress. Despite this, the impact of hydrogen damage on the fretting wear behavior of HEA coatings has not been explored. To address this, we performed fretting wear tests on a laser-cladded FeCoCrNiMo0.2 coating and a GCr15 steel ball friction system, evaluating their performance before and after hydrogen exposure. The results of the study indicate that under a constant load of Fn = 10N and a displacement amplitude of D = 50 μm, the friction coefficient, maximum wear depth, wear volume, and wear rate increased when the system was in the hydrogen charging state compared to the non-hydrogen charging state. Specifically, the friction coefficient increased from 0.60 to 0.93, the maximum wear depth increased from 2.82 μm to 3.63 μm, the wear volume increased from 14.106 × 104μm3 to 22.098 × 104μm3, and the wear rate increased from 28.213 × 10−6 mm/Nm to 36.600 × 10−6 mm/Nm. Under the hydrogen charging state, the friction coefficient, maximum wear depth, wear volume, and wear rate all increased. This is due to hydrogen damage, including the formation of pitting pits and cracks on the surface of the coating, stress concentration, and brittle failure caused by hydrogen infiltration into the material. The presence of hydrogen makes the surface of the coating more prone to detachment, resulting in finer wear debris, deeper grooves, and increased oxidation. These factors accelerate the wear of the coating. This finding will contribute to the development and improvement of advanced surface modification techniques for materials in the hydrogen environment.

Large-signal stability analysis of an islanded DC microgrid with constant power loads based on mixed potential function

Abstract In DC microgrids, power electronic converters are widely used to connect loads and renewable energy sources to generate different voltages. These loads operate as constant power loads (CPL) within a closed control loop. When voltage fluctuates, these loads display negative impedance characteristics, potentially leading to system instability. Therefore, the analysis of the impact of CPL on DC microgrids during large disturbances is crucial. This paper employs mixed potential theory to study the large disturbance stability of DC microgrids under CPL. Deriving the stability criterion for the system under significant perturbations reveals the impact of load types and control parameters on system stability and provides a detailed analysis of how specific system parameters affect stability. Consequently, the stability criterion can ensure the system’s stability under large disturbances without the need for repeated calculations and simulations. Simulation results verify the correctness of this stability criterion.

Mechanical and metallurgical assessment of a submerged arc welded surfaced rail

The surfaces of rails are often damaged during constant loading, so it is essential to repair the damaged areas in a railroad network to get the best performance. However, the traditional methods of improving rails are expensive, time-consuming, and require excessive effort. Therefore, some creative ideas would be helpful in this process, one of which may be on-site overlay arc welding instead of exchanging the whole part of the rail. In this paper, the performance of such a method is assessed experimentally, and its results are interpreted.For the investigation, a worn part of the 136RE rail, used in the freight railway network in the U.S., was chosen. After milling and flattening the surface of the rail, a submerged arc welding process was applied to rebuild this rail by utilizing a 1/8-in Lincore 40-S depositing wire. This study used four destructive tests: 1) XRD residual stress measurement, 2) SEM/OM analysis, 3) hardness test, and 4) tensile test. The results showed that the required mechanical strength could be achieved. However, the repaired area seems more vulnerable to the forces encountered on a railroad network due to the more brittle structure due to high temperatures in this region. Considering this flaw is critical because forces are primarily dynamic in railway networks, especially in heavy rails, which are higher due to the extensive use of freight trains.

Acute partial sleep deprivation attenuates blood pressure responses to cycling exercise.

Exaggerated blood pressure (BP) responses during exercise are independently associated with future development of hypertension. Partial sleep deprivation (PSD) can increase 24-h ambulatory BP, but the effects on exercise BP are unclear. We hypothesized that acute PSD would augment the BP response to constant load cycling exercise and a 20-min time trial. Twenty-two healthy adults (22 ± 3 yr old; 13 males; V̇o2peak, 43.6 ± 8.2 mL·kg-1·min-1) completed a randomized crossover trial in which they either slept normally (normal sleep-wake schedule for each participant) or sleep was partially deprived (early awakening, 40% of normal sleep duration). Each participant completed a 12-min warm-up consisting of two 6-min steps (step 1, 62 ± 25 W; step 2, 137 ± 60 W) followed by a 20-min time trial on a cycle ergometer. PSD did not alter power output during the 20-min time trial [(control vs. PSD) 170 ± 68 vs. 168 ± 68 W, P = 0.65]. Systolic BP did not differ during step 1 of the warm-up (141 ± 15 vs. 137 ± 12 mmHg, P = 0.39) but was lower following PSD during step 2 (165 ± 21 vs. 159 ± 22 mmHg, P = 0.004) and the 20-min time trial (171 ± 20 vs. 164 ± 23 mmHg, P < 0.001). These results were maintained when peak oxygen uptake (V̇o2peak) was included as a covariate. Systolic BP responses were modulated by sex (time × visit × sex interaction P = 0.03), with attenuated systolic BP during the warm-up and the 20-min time trial in males but not in females. In contrast to our hypothesis, acute PSD attenuates systolic BP responses during constant load and 20-min time trial cycling exercise; however, these observations appear to be primarily driven by changes in males.NEW & NOTEWORTHY A single night of partial sleep deprivation (PSD) can increase ambulatory blood pressure (BP) the following day. Despite this phenomenon, the present study found that acute PSD attenuates systolic BP responses to both constant load cycling and a 20-min cycling time trial in young healthy adults. Interestingly, the attenuated systolic BP responses following PSD appeared to be modulated by sex such that attenuations were observed in males but not in females.

Exploiting the determinant factors on the available flexibility area of ADNs at TSO‐DSO interface

AbstractActive distribution networks (ADNs) are consistently being developed as a result of increasing penetration of distributed energy resources (DERs) and energy transition from fossil‐fuel‐based to zero carbon era. This penetration poses technical challenges for the operation of both transmission and distribution networks. The determination of the active/reactive power capability of ADNs will provide useful information at the transmission and distribution systems interface. For instance, the transmission system operator (TSO) can benefit from reactive power and reserve services which are readily available by the DERs embedded within the downstream ADNs, which are managed by the distribution system operator (DSO). This article investigates the important factors affecting the active/reactive power flexibility area of ADNs such as the joint active and reactive power dispatch of DERs, dependency of the ADN's load to voltage, parallel distribution networks, and upstream network parameters. A two‐step optimization model is developed which can capture the P/Q flexibility area, by considering the above factors and grid technical constraints such as its detailed power flow model. The numerical results from the IEEE 69‐bus standard distribution feeder underscore the critical importance of considering various factors to characterize the ADN's P/Q flexibility area. Ignoring these factors can significantly impact the shape and size of Active Distribution Networks (ADN) P/Q flexibility maps. Specifically, the Constant Power load model exhibits the smallest flexibility area; connecting to a weak upstream network diminishes P/Q flexibility, and reactive power redispatch improves active power flexibility margins. Furthermore, the collaborative support of reactive power from a neighboring distribution feeder, connected in parallel with the studied ADN, expands the achievable P/Q flexibility. These observations highlight the significance of accurately characterizing transmission and distribution network parameters. Such precision is fundamental for ensuring a smooth energy transition and successful integration of hybrid renewable energy technologies into ADNs.

Hydrogen permeation behavior of X80 pipeline steel under alternating wet-dry environment in the South China Sea

The riser sections of offshore pipelines are subject to cathodic potentials, alternating wet-dry (AWD) cycles and stresses in the service environment. The hydrogen permeation of X80 offshore pipeline with different cathodic potentials, dry/wet ratios, and constant tensile stress in AWD environment were investigated by the self made experimental equipment, which includes the three modules, i.e., the constant stress loading, the two-component cell hydrogen permeation, and AWD environment. Results showed that hydrogen permeation current fluctuates with the AWD, which is different from that in the bulk solution. In one AWD cycle, the permeation increases in the wetting stage and decreases in the dry stage. The smaller the dry/wet ratio, the longer the hydrogen permeation current keeps high level which is caused by the dense corrosion product layer. The hydrogen permeation currents in the elastic stress are greater than those in the plastic deformation, and unstressed conditions is the smallest.

Enhancing disturbance rejection in boost converter for CPL: A controller design approach with partial pole placement and approximate model matching

In DC microgrids, the cascade operation of the DC-DC converters leads to a constant power load fed by the boost converter, resulting in unstable behavior in addition to the non-minimum phase dynamics. An enhanced load disturbance rejection control scheme based on partial pole placement and an approximate model matching technique is proposed. This approach is inspired by the well-known direct synthesis method to achieve optimal load disturbance rejection performance. The effectiveness of the proposed control scheme has been validated through hardware implementation, demonstrating its capability in setpoint tracking and load disturbance rejection under variations in load power and input voltage. The robust stability of the suggested scheme has been investigated through the Kharitonov theorem and Monte-Carlo simulation, considering different performance matrices. The suitability of the presented scheme has been established by analyzing the comparative performance of recently reported works. The proposed controller reduces peak overshoot and settling time by ∼50%, handles system uncertainties up to 75%, and outperforms FOPID controllers tuned with particle swarm optimization, queen bee genetic algorithm, and chaos game optimization methods.

On the Maximum Power of Passive Magnetic Energy Harvesters Feeding Constant Voltage Loads Under High Primary Currents

On the Maximum Power of Passive Magnetic Energy Harvesters Feeding Constant Voltage Loads Under High Primary Currents

Understanding the deformation creep and role of intermetallic compound-microstructure in Sn-Ag-Cu solders

Tin-based alloys are commonly used in lead-free solder joints in electronic interconnection applications, where creep can limit joint reliability. In this work, directionally solidified bulk solder alloys of different compositions (pure tin, SAC105 and SAC305) are mechanically tested under a constant load for each composition at room temperature to understand mechanical creep performance and quantify the role of different content of Ag3Sn and Cu6Sn5 intermetallic compounds (IMCs) in terms of secondary creep strain rate, microstructural evolution, and total amount of accumulated strain. In this work, microstructures are fabricated using directional solidification to promote a systematic variation in IMC sizes, shapes, and distributions within similar crystal orientations of the primary β-Sn matrix. Analysis of creep data indicates that secondary creep is dominated by obstacle-controlled dislocation motion. This is further confirmed by electron backscatter diffraction (EBSD) analysis, which reveals that the formation of subgrains and internal structure, correlating to the initial microstructure of the sample, i.e. changes in secondary dendrite arm spacing (λ2) and eutectic intermetallic spacing (λe). The experimental observations are supported further by crystal plasticity simulations that explicitly model the presence of IMCs within the Sn-based samples and show the dependence of the secondary creep rate upon the IMC content, and therefore be beneficial for the possible future composition design in solders.

Buckling Loads of Variable Stiffness Columns Loaded by Top Load and Linearly and Parabolically Distributed Loading

This work presents approximate, numerical and exact series solutions for the buckling of variable cross-section columns. The loading on the columns includes tip load, distributed load along the column, and several combinations of these. Solutions are presented for nine combinations of boundary conditions at the two ends of the column. The analysis includes constant cross-section columns with constant distributed load and linearly varying distributed loads. Variable cross-section cases include columns with linear variations of the stiffness, bi-linear variations variation of the stiffness, parabolic variations and bi-parabolic variations variation of the stiffness for columns with rectangular cross-section. The results are compared by the three methods. Many new benchmark results are given for all these cases.

ANALYTICAL CALCULATION OF A BEAM BASED ON AN ELASTIC WINKLER FOUNDATION WITH RANGE INHOMOGENITY

The aim of the study is the further development of analytical methods for calculating the bending of beams resting on a non-homogeneous continuous Winkler elastic foundation. This paper considers the case when the beam is under the influence of a uniformly distributed constant transverse load, and the inhomogeneity of the elastic foundation is given by a power function with an arbitrary non-negative power exponent . Fundamental functions and a partial solution of the corresponding differential equation of beam bending are found in an explicit closed form. These functions are dimensionless and are represented by absolutely and uniformly convergent power series. In turn, the formulas for the parameters of the stress-strain state of the beam – deflection, angle of rotation, bending moment and transverse force – are expressed through the indicated functions. The unknown constants of integration in these formulas are expressed in terms of the initial parameters, which are after the implementation of the specified boundary conditions. Thus, the calculation of the beam for bending is reduced to the procedure of numerical implementation of explicit analytical formulas for the parameters of the stress-strain state. An example demonstrates the practical application of the obtained solutions. A prismatic concrete beam based on a cubic variable elastic foundation is considered. This case corresponds to the power value . The results of the calculation by the author's method are presented in numerical and graphical formats for the case when the left end of the beam is hinged and the right end is clamped. The numerical values obtained by the author's method are accurate, since the applied calculation method is based on the exact solution of the corresponding differential equation. The availability of such solutions makes it possible to evaluate the accuracy of solutions obtained using various approximate methods by comparison. For the purpose of such a comparison, the paper presents the calculation results obtained by the finite element method (FEM). The absolute error of the FEM method when calculating this design was determined.

High protonic resistance of hydrocarbon-based cathodes in PEM fuel cells under low humidity conditions: Origin, implication, and mitigation

Hydrocarbon-based electrodes for proton-exchange membrane fuel cells face challenges in closing the performance gap with electrodes based on perfluorosulfonic acid ionomers, particularly under low humidity conditions. Alongside increased oxygen transport resistance and higher kinetic-induced overpotentials, the protonic resistance of these fluorine-free electrodes is the primary hurdle to improved performance. This study systematically investigates the origin and impact of the cathode protonic resistance on fuel cell performance, utilizing sulfonated phenylated polyphenylenes as hydrocarbon ionomers. Electrochemical characterization at low relative humidity (≤50 %) reveal a high protonic resistance arising from both lower conductivity of the hydrocarbon thin film compared to the bulk membrane and increased cathode tortuosity at a gas transport-optimized ionomer to carbon (I/C) ratio of 0.2. The poor protonic resistance at low relative humidities leads to a non-homogeneous current distribution across the thickness of the cathode electrode, resulting in lower catalyst utilization. To address this issue, reducing the thickness of the cathode CL while maintaining a constant Pt loading (i.e., increasing the Pt on carbon ratio) significantly reduces protonic resistance. This improvement compensates for the kinetic disadvantages of highly loaded carbon particles and results in a considerable performance increase by 40 % at 0.75 V under low relative humidities.

Topology design of variable speed drive systems for enhancing power quality in industrial grids

In the last two decades, a rapid increase in the utilization of non-linear loads within electrical grids has been observed. Consequently, elevated levels of harmonics are found in both voltage and current waves, and adverse effects on power quality are caused. In this context, the variable speed drive (VSD) systems are considered a significant non-linear contributor. To mitigate the harmonic content in VSD systems, various techniques are explored, such as electronic smoothing inductor incorporation in the DC-link, active filters utilization at the grid side, and passive filters integration. A technique centered on the reconfiguration of the DC-link in the VSD systems is proposed in this paper to improve the overall performance of the VSD systems. The configuration comprises two transistors and two diodes, along with smoothing inductors and a capacitor to enhance power quality in the VSD systems. The utilization of three-stage sine pulse width modulation (SPWM) control technology ensures accurate control of the switches, generating optimal control signals that enhance the power quality of the voltage and current waves at the grid side. The effectiveness of the proposed approach is tested via time-domain simulation in MATLAB/Simulink under both constant and variable loading conditions and is verified using a laboratory prototype. The obtained results demonstrate a notable improvement in power quality, showcasing reduced total harmonic distortion (THD) in AC voltage and current waveforms, as well as minimized ripple factor in the DC-link when compared to existing methods.

A Temperature-Robust Envelope Detector Receiving OOK-Modulated Signals for Low-Power Applications

This paper presents a passive Envelope Detector (ED) to be used for reception of OOK-modulated signals, such as in Wake-Up Receivers employed within Wireless Sensor Networks, widely used in the IoT. The main goal is implementing a temperature compensation mechanism in order to keep the passive ED input resistance roughly constant over temperature, making it a constant load for the preceding matching network and ultimately keeping the overall receiving chain sensitivity constant over temperature. The proposed ED was designed using STMicroelectronics 90 nm CMOS technology to receive 1 kbps OOK-modulated packets with a 433 MHz carrier frequency and a 0.6 V supply. The use of a block featuring a Proportional-to-Absolute Temperature (PTAT) current yields a 5 dB reduction in sensitivity temperature variation across the −40 °C to 120 °C range. Moreover, two different implementations were compared, one targeting minimal mismatch and the other one targeting minimal area. The minimal area version appears to be better in terms of estimated overall chain sensitivity at all temperatures despite a higher sensitivity spread.

LOADS ON SUBMERGED WALLS OF PROTECTIVE STRUCTURES

The intensification of military operations on the territory of Ukraine, which are accompanied by missile attacks and bombing of territories, requires the use of reliable protective structures. Modern codes require the provision of each new building with storage facilities that guarantee the safety of life and health of citizens, so the correct determination of all loads on the structural elements of protective structures is an urgent issue. Taking into acoount the fact that the previous codes were somewhat outdated and had limited access for a long time, a significant event was the adoption in 2023 of new codes for the design of protective structures of civil defence. The main requirements and recommendations of SBC B.2.2-5:20023 were taken into account when conducting research on determining the loads on buried walls of bomb shelters. Such structures, as we know, perceive a constant load from the lateral pressure of the soil, which during an explosion is supplemented by an episodic load from the action of an air wave. Modern specialized literature contains rather limited information on scientific research and development in the field of design of protective structures. An actual issue is also the study of the influence of determining factors on the intensity of the load on the walls of buried protective structures and the possibility of its adjustment in order to reduce it. Taking into account the nature of the distribution of loads on the underground walls of bomb shelters, a dependence was obtained to determine the resulting active pressure and quasi-static load caused by the action of an air wave. The pressures from the soil and the blast wave at different orientations of the contact wall and for different types of soil environment were studied. The loads in contact of a smooth and rough wall with sandy, sandy and loamy soils with different indicators of physical and mechanical characteristics were considered. The obtained results indicate a significant influence of the geometric parameters of the wall and the features of the contact soil on the resulting pressure, which can vary depending on the studied factors by 10-20%, which indicates the possibility of reducing the load on protective structures, operating with the considered indicators.

Systematization of the application of polymer composite materials in the design of bridge structures

Background. This study systematizes the principles of using polymer composite materials in bridge structure design, outlining the fundamental principles for calculating load-bearing structures of bridge spans featuring these materials. Aim. The goal is to enhance the strength and durability of bridge spans during construction and maintenance, while optimizing costs through the use of polymer composite materials. Materials and Methods. The research employs a modern approach to bridge structure design, utilizing mathematical statistics for experimental data analysis and numerical methods for calculating bridge structures using nonlinear deformation models of anisotropic materials. Results. Developed principles for designing bridge spans with polymer composite elements include methods for strengthening and reinforcing concrete bridge structures. These methods account for operational factors such as long-term constant and temporary loads, low and elevated temperatures, as well as methods for designing all-composite spans pedestrian and road bridges Conclusion. The principles of designing bridge spans with elements made of polymer composite materials have been introduced into the practice of transport construction in the Russian Federation. The technical and economic efficiency of using polymer composite materials in bridge structures of transport infrastructure has been confirmed.