Bending Moment Research Articles

SYNTHESIS OF RATIONAL CONSTRUCTIVE SOLUTION OF STEEL ROOF TRUSSES

The article examines the issue of the occurrence and influence of bending moments on the bearing capacity of a combined steel truss made of rectangular bent-welded profiles. A comparative analysis of technical and economic indicators in terms of material intensity, labor intensity, and cost of traditional-typical and lightweight combined steel trusses was carried out. The paper examines steel trusses of long-span buildings with a span of 30 m. The force graphs (bending moments and axial forces) for various calculation schemes of the combined steel truss are shown. An analysis of the forces in the combined truss for different ways of connecting the lattice to the chords was carried out. The plot of normal stresses along the middle line of the stiffening girder of the combined truss for various calculation schemes is presented. The load-bearing capacity of compressed rods with different connection methods was calculated. According to the research results, an engineering method of taking into account the influence of bending moments is proposed.

Investigation into soil ratcheting behind integral bridges using centrifuge modelling

Integral bridges in the UK are commonly designed according to PD 6694-1:2011, with guidance on backfill ratcheting based on experimental data that is limited by testing at a small-scale low-stress state, a lack of abutment foundation and soil below, and a limited range of soil–structure configurations. As integral bridge use increases, there is a need for further understanding of the strain ratcheting mechanism, which can lead to smarter designs that minimise material usage and lifetime maintenance. The suitability of modern centrifuge techniques to simulate ratcheting of soil behind an integral bridge abutment over a design life of thermal loading was investigated. A high-accuracy actuation system was developed and employed in centrifuge testing, with test data provided to demonstrate its capabilities. Surface settlements, deck axial forces and abutment bending moment distributions recorded for various soil–structure combinations were compared, highlighting the sensitivity of soil ratcheting. This work shows that centrifuge modelling can successfully simulate backfill strain ratcheting behind integral abutments over a range of soil–structure configurations. Furthermore, the results suggest that global rotations and base sliding are significant to the overall response, clarifying the importance of modelling at an appropriate stress state with a foundation and the soil below.

Mechanical performance of patient-specific prefabricated temporary shell versus laboratory-fabricated CAD/CAM provisional implant-supported single-tooth restorations: Alaboratory study.

To evaluate the mechanical performance of patient-specific prefabricated temporary shell versus laboratory-fabricated CAD/CAM provisional restorations on titanium temporary abutments, with and without thermo-mechanical ageing. Implants with a conical connection were divided into four groups (n = 24) and restored with temporary shell or laboratory-fabricated central or lateral incisor PMMA restorations that were relined or bonded on titanium temporary abutments. The diameter of the central and lateral incisor groups' implants was regular (ϕ 4.3 mm) or narrow (ϕ 3.5 mm), respectively. Half of each group's specimens were subjected to ageing, simultaneous thermocycling (5-55°C) and chewing simulation (120,000 cycles, 50 N, 1.7 Hz) resulting in eight groups in total (n = 12). The aged specimens were evaluated with optical microscopy, and survival and complication rates were determined according to modified USPHS criteria. The non-aged specimens and those that had survived ageing were loaded until failure, whereupon bending moments were calculated. Survival rates after ageing were 100% for all groups. Apart from wear facets (ϕ 2-3 mm) on the palatal restoration surface, no complications were observed. The mean fracture load and bending moments ranged between 597.6-847.1 N and 433.3-550.6 Ncm, respectively, with no significant differences between the eight groups (p = .25; p = .20). As patient-specific temporary shell central and lateral incisor provisional implant-supported restorations are mechanically stable enough to withstand clinical bite forces, even after thermo-mechanical ageing, they may serve as an alternative to laboratory-fabricated provisional restorations.

Branch Break Assessment: An Unexpected Accident with a Professional Arborist

AbstractBackgroundArborists are important in both the maintenance of urban trees and research on forest canopies. Tree climbing is hazardous work. This study investigated the causes of a branch-breaking accident involving a certified arborist.MethodsThe branch was 11 cm in diameter. The density and mechanics of the branch wood were studied; the measurable stresses and deformations until the material ruptured were analyzed. The position of the tree climber and the applied forces were calculated, including the shear stresses, the bending moment, and the support reaction suffered at the point of rupture.ResultsThe shear stress grew exponentially fromV= 25.78 MPa; a shifting of the angle of the lanyard by > 45° and moving one meter toward the tip of the branch caused a 64.67% increase in shear stress. The support distance of the arborist’s body on the one anchor point on the branch, combined with the angle of force on the same branch, caused the imminent rupture of the branch’s base. The study provides evidence that the arborists should avoid traveling over small horizontal branches using only one safety point with lanyards.

Pressure and thermal effects on Rayleigh fiber-optic strain measurment for soil-structure interaction

Optical strain sensing in civil engineering has been adopted for both field applications and advanced laboratory testing of structural health monitoring. Rayleigh backscatter devices (ROFDR) are presented for use with geotechnical centrifuge research since they offer distributed sensing capabilities, and through this study have been shown to have negligible interference from pressure effects, and can be made with low-cost disposable sensors. A comparison between a single channel and multi-channel fiber optic rotary joint (FORJ) is presented in the context of transmitting optical strain data across a rotating interface. The orthogonal pressure effects (eg. From soil) of a free-floating fiber under isotropic pressure was less than 0.32 με / kPa and that the pressure effect on a fiber bonded to a metal surface was below the detection limit of the instrument, 1 με, for an applied pressure of 60 kPa. The ROFDR system showed highly repeatable measurement of a constant temperature reading through the use of a water bath experiment. The system is stable to +/- 10 microstrain within 2-sigma for a >12 hr constant temperature test. An example case of a pipeline buried in a slope experiencing a landslide is presented where the optical strain sensing is used to capture strain pairs along the crownline and pipe invert to capture bending moment of the pipeline. Geotechnical centrifuge modelling in a 1 metre drum was carried out using a multi-channel FORJ coupled with an ROFDR system.

Influence of end restraint strength on the structural fire behavior and deterioration mechanism of RC frame beams

AbstractThe end restraint strength of the reinforced concrete (RC) beams under the fire conditions may greatly influence the inner force redistribution and the structural behavior of the beams, even the stability of the whole structure. The structural fire behavior of two full‐scale frame beams with different end restraint strength under load were studied based on experiment and simulation. The temperature field, reinforcement strain, beam deflection, end axial displacement, and rotation angle of the structure during the whole heating and cooling process were measured. The influence of end restraint strength on the structural behavior was analyzed. The results show that the vertical displacement, axial force, end bending moment, and angular displacement first increase rapidly, then decrease gradually and become stable in the whole process; the lateral displacement increases first and then stabilizes; the change of axial and rotational deformations appeared to be non‐proportional with the corresponding restraining forces, reflecting that the axial and the rotational restraint strength at the ends of the beams decreased with the rise of temperature. The restraining strength of beams that submitted to fire globally decreased faster, and leading to a severe fire response and an earlier failure of the structure. The analysis results and the conclusions will supply scientific basis for the fire‐resistance design and safety evaluation on complex structures.

Experimental Study on the Horizontal Bearing Characteristic of a Strip-Walled Underground Diaphragm Wall

Researching and developing a new type of diaphragm wall foundation can solve the probl em that the traditional diaphragm wall structure may not meet the high standards of safety and stability of underground structures in some specific engineering environments. This paper focuses on the horizontal bearing characteristic of a new form of foundation, a strip-walled underground diaphragm wall, through a series of model tests. In the tests, nine plexiglass models with different section sizes, wall spacings and wall heights, as well as loading strategies (horizontal loads along and against the wall in the model), were conducted. The influence of the above factors on the horizontal bearing performance of the foundation and the soil resistance distribution around the wall was studied. The results show that when the horizontal load applied along the wall is greater than 50 N, the growth rate of total displacement at the top of the wall gradually decreases; when a horizontal load is applied against the wall, with a uniform change in wall height, the optimal wall spacing is 11 cm. When the same displacement occurs, the bearing performance of the model under the former loading strategy is generally 10% higher than that under the later loading strategy. In addition, the depth where the maximum bending moment along the wall occurred gradually moves downward with the increase in horizontal load, and the increase in wall spacing and wall height has a positive effect on the horizontal bearing characteristic. With the application of load, the maximum bending moment of the wall will gradually decrease along the depth. The increase in wall spacing and wall height can improve the overall flexural stiffness and horizontal bearing performance of the foundation. Lastly, the group wall effect coefficient, β, is put forward, and a simplified formula for calculating the horizontal bearing capacity of a strip wall foundation is proposed. In the formula, β is negatively correlated with the buried depth of the wall and positively correlated with the distance between the walls, and its coefficient is greater than 1.

Bending Performance of a Prestressed Concrete Composite Girder Bridge with Steel Truss Webs

An experiment was conducted on a prestressed concrete (PC) composite girder bridge with steel truss webs to investigate its flexural performance. The mechanical characteristics and failure modes of a PC composite girder bridge with steel truss webs was clarified. Finite element (FE) analysis was carried out, and the influence of the girder height-to-span ratio and eccentric loading effect on the flexural performance of a composite beam bridge with a steel truss web was discussed. The method for calculating the cracking bending moment, the bending moment at the rebar yield stage, and the ultimate bending moment of a PC composite girder with steel truss webs was proposed. Key findings include that, in both the elastic and cracking elastic stages, the strain of the bottom and top conforms to the plane-section assumption. Throughout the loading process, there was no occurrence of joint failure or local buckling failure in the steel truss webs; the composite girder ultimately fails due to excessive deformation, indicating that the overall mechanical performance of the composite beam is good. The deflection and stress in the mid-span section decrease with an increasing height-to-span ratio, and there are significant impacts of eccentric loading on deflection and stress. Compared with the results of the FE analysis and test, the calculation methods of the cracking moment, reinforcement yield moment, and ultimate moment of PC composite girders with steel truss webs presented in this paper have a high accuracy.

The analytical model of crimping springback for large-diameter longitudinal welded pipe

The crimping technique is widely used in the manufacturing process of large-diameter longitudinal welded pipe. In the bending process, the springback is the critical problem affecting the shape, which is the key index of forming quality. So, crimping faces more challenges in accurate springback prediction for difficult-to-form metals such as pipeline steels and non-circular nature of the punch. This paper has established an analytical model of crimping springback for the longitudinal welded pipe. Firstly, the crimping process mathematical model which considered the impact of elastic modulus attenuation on springback calculation during plastic deformation is established, and the cross-section bending moment is calculated based on Hill’s bending theory. Secondly, a semi-analytical and semi-numerical method for calculating the crimping shape is presented. Finally, the comparison of the crimping shape of the real product shows that the calculation accuracy and efficiency of this method can meet the requirements of engineering applications. The relative error of the springback angle calculated by the analytical model is −5.84%, and the absolute error is 0.3°. This method can accurately predict the springback of longitudinal welded pipe after crimping and provide a reference for crimping process optimization.

Optimization of Staging Height of RCC Overhead Water Tank in High Seismic Zones Using P-Delta Analysis

Abstract: This study investigates the P-delta effect, which is a secondary effect or a geometric non-linear effect in the analysis of a circular overhead water tank with a capacity of 100 KL using STAAD software in high seismic zones, i.e., Zone IV & Zone V with a focus on optimization of staging height and to quantify the effect of P-Delta. Initially, a linear static analysis was performed without considering the P-Delta effect to determine the shear forces, bending moments and lateral displacements due to all possible loads including seismic and wind loads acting on RCC overhead water tanks. Subsequently, the P-Delta effect has been considered to assess the structural behaviour of the RCC overhead water tank with varying staging heights. To optimize the staging height, the maximum lateral displacement has been considered as the governing criteria. Based on the analysis, the optimum staging heights can be observed at 30 m. and 33 m. in Seismic Zone V and Zone IV respectively

Design and Implementation of Water PH Level and Turbidity Monitoring System

Abstract: Building collapses have become a distressing and recurring issue in Nigeria, necessitating urgent action to mitigate their occurrence. This paper introduces an innovative approach to address this challenge by developing an Automated Structural Health Monitoring System (ASHMS) utilizing a mobile app. Focusing on major cities like Lagos and Abuja, the proposed system employs strategically placed sensors to gather data from various structural elements of buildings. The collected information, encompassing seismic activity, vibrations, bending moments, shear forces, and other key parameters, is wirelessly transmitted to the cloud where it can then be accessed and visualized using mobile app. The system offers real-time insights into the structural integrity of buildings and provides early warnings, thereby contributing significantly to reducing the risk of building collapses. Key findings show that when incorporated into an automated Structural Health Monitoring (SHM) system, the user's mobile app offers essential structural insights, capturing values such as a 0.5-unit vibration level, 20 units of shear force, 50 units of bending moment, and an 89-degree vertical wall angle. The app's userfriendly interface improves the effectiveness of monitoring and overseeing structural health, in line with the overarching objective of promoting safety in construction practices

Automated Structural Health Monitoring System for Mitigating Building Collapse in Nigeria: A Mobile App Approach

Abstract: Building collapses have become a distressing and recurring issue in Nigeria, necessitating urgent action to mitigate their occurrence. This paper introduces an innovative approach to address this challenge by developing an Automated Structural Health Monitoring System (ASHMS) utilizing a mobile app. Focusing on major cities like Lagos and Abuja, the proposed system employs strategically placed sensors to gather data from various structural elements of buildings. The collected information, encompassing seismic activity, vibrations, bending moments, shear forces, and other key parameters, is wirelessly transmitted to the cloud where it can then be accessed and visualized using mobile app. The system offers real-time insights into the structural integrity of buildings and provides early warnings, thereby contributing significantly to reducing the risk of building collapses. Key findings show that when incorporated into an automated Structural Health Monitoring (SHM) system, the user's mobile app offers essential structural insights, capturing values such as a 0.5-unit vibration level, 20 units of shear force, 50 units of bending moment, and an 89-degree vertical wall angle. The app's userfriendly interface improves the effectiveness of monitoring and overseeing structural health, in line with the overarching objective of promoting safety in construction practices.

Design and Analysis of General Hospital Building Using STAAD Pro

Abstract: Structural design is the primary aspect of the civil engineering. The foremost basic in structural engineering is the design of simple basic components and members of a building viz., Beams, Columns and Footings. The principal objective of this project is to analyze and design a general hospital using Staad pro. The design involves manual load calculations, analysis and design of the whole structure using STAAD Pro. The design methods used in STAAD-Pro analysis are Limit State Design conforming to Indian Standard Code of Practice. Structure considered for analysis and design is 21m high hospital building located in the seismic zone III. In this project, we study the effect of various load combinations on the structure by analysing the bending moment diagrams in post processing mode. The project involves detailed drawings of column layout, column detailing and beam detailing

Numerical Investigation into the Stability of Offshore Wind Power Piles Subjected to Lateral Loads in Extreme Environments

Monopile foundations are extensively utilized in the rapidly expanding offshore wind power industry, and the stability of these foundations has become a crucial factor for ensuring the safety of offshore wind power projects. Such foundations are subjected to a myriad of complex environmental loads during their operational lifespan. Whilst current research predominantly concentrates on the effects of wind, wave, and current loads on monopile stability in extreme environments, it is imperative to consider the potential influence of unexpected submarine landslide loads. In this study, we provide a comprehensive overview of wind, wave, current, and submarine landslide loads on monopile foundations in extreme environments. Subsequently, we establish a finite element model for analyzing the stability of monopiles under complex lateral loads, and validate the accuracy of the model by comparing it with the previous numerical findings. A case study is performed with reference to the Xiangshui Wind Farm project to analyze the effects of varying submarine landslide densities, velocities, impact heights, and seabed sediment strengths on pile head horizontal displacement, pile rotation at the mudline, and maximum bending moment. The findings indicate that the increase in submarine landslide density, velocity, and impact height leads to an increase in horizontal displacement at the pile head, pile rotation at the mudline, and maximum bending moments, and a horizontal failure mode is observed in seabed sediments. Furthermore, under the same load conditions, a decrease in seabed sediment strength and internal friction angle triggers instability in monopiles, with a noteworthy transition from horizontal failure to deep-seated seabed sediment failure. Finally, we propose a criterion for monopile instability under diverse loading conditions.

Research on the Method of Prestressing Tendon Layout for Large-Span Prestressed Components Continuous Rigid Frame Bridge Based on “Zero Bending Moment Dead Load Theory”

Research on the Method of Prestressing Tendon Layout for Large-Span Prestressed Components Continuous Rigid Frame Bridge Based on “Zero Bending Moment Dead Load Theory”

Reliquefaction behavior of sand and response of pile group subjected to repeated shaking sequence using centrifuge model experiments

A series of centrifuge model experiments were performed in this study to investigate the sand reliquefaction behavior in free field and pile group models subjected to repeated shakings. Toyoura sand was used to prepare the model ground with 50 % relative density and experimented at 50g centrifugal acceleration. A 2 × 2 pile group model was used to examine the response of piles and its effect on sand reliquefaction during repeated shakings. A seismic sequence comprising foreshocks–mainshock–aftershocks–mainshock pattern was imparted to both free field and pile group models. In addition, an independent mainshock was imparted to a free field model and compared with the seismic sequence to examine the effect of foreshocks in triggering future liquefaction. Acceleration time response, excess pore pressure (EPP), ground subsidence, bending moment and lateral displacement of the pile group were measured. Significant de-amplification and unsymmetrical response with presence of shear-induced dilatancy spikes were observed in both free field and pile group models. Results from this study indicate that foreshocks and aftershocks are not sufficient to induce liquefaction. However, liquefaction and subsequent reliquefaction were recorded in both models during mainshocks. Pile group recorded smaller EPP response and subsidence compared to free field model. Higher magnitude of reliquefaction was induced even at moderate depths during the second mainshock at a quicker time. This was primarily associated with the increase in magnitude of anisotropy due to repeated generation and dissipation of pore water which results in decrease in resistance to further reliquefaction. Hardening induced around the vicinity of the pile group due to sand densification has resulted in smaller bending moment values during second mainshock compared to the first.

Numerical and artificial neural network analysis of tunnel liner design parameters – a comparative study

ABSTRACT This paper proposes the development of an analytical-based Artificial Neural Network (ANN) model for predicting the concrete segmental lining parameters and comparing it with the finite element method, Rocscience tool. To achieve this aim, the dataset was prepared for twelve different loading conditions using the analytical equations by Muir Wood and Curtis. Using this dataset, an ANN model was developed for predicting the segmental lining parameters, viz. displacement, bending moment, axial and shear force. Furthermore, the Rocscience tool was used to analyse the aforementioned design parameters, and the results of these two methods were compared and summarised. It is found that the developed ANN model shows reasonable results of liner design parameters with the Rocscience program. The efficiency of both techniques was evaluated using the statistical measures viz. Mean Absolute Error, Root Mean Square Error, and Coefficient of Efficiency. It is observed that the ANN model is best fitted for the prediction of liner shear and axial force, while it could not find the optimised solution for liner displacement and bending moment. The finding of this study showed that the developed ANN model can be applied to predict the tunnel liner design parameters instead of the alternative complicated and time-consuming techniques.

Limit state equation and failure pressure prediction model of pipeline with complex loading

Assessing failure pressure is critical in determining pipeline integrity. Current research primarily concerns the buckling performance of pressurized pipelines subjected to a bending load or axial compression force, with some also looking at the failure pressure of corroded pipelines. However, there is currently a lack of limit state models for pressurized pipelines with bending moments and axial forces. In this study, based on the unified yield criterion, we propose a limit state equation for steel pipes under various loads. The most common operating loads on buried pipelines are bending moment, internal pressure, and axial force. The proposed limit state equation for intact pipelines is based on a three-dimensional pipeline stress model with complex load coupling. Using failure data, we investigate the applicability of various yield criteria in assessing the failure pressure of pipelines with complex loads. We show that the evaluation model can be effectively used as a theoretical solution for assessing the failure pressure in such circumstances and for selecting appropriate yield criteria based on load condition differences.

Forming of monoaxially curved thin-walled T-section integral panels by double-sided laser peening

Thin-walled T-section integral panels are widely used in the aerospace industry for achieving lightweight and high performance, but their strict manufacturing requirements present challenges to current forming processes. This study proposes the double-sided laser peening (DSLP) process and develops corresponding models to achieve the forming of monoaxially curved T-section integral panels. An eigen-force model is derived to describe deformation behavior and reveal the underlying forming mechanism. The results indicate that bending deformation is driven by the moment originally induced by the in-plane eigen-force deviating from the neutral plane. Full-covered DSLP on the skin results in bending deformation towards the stiffeners, and vice versa. Additionally, DSLP on complementary regions induces identical bending deformations in opposite directions. The undesired bending distortion appeared in single-sided laser peening is eliminated by DSLP, as the action point of the eigen-force migrates to the neutral plane of the skin or stiffeners after DSLP, thereby preventing the generation of bending moments. Subsequently, drawing inspirations from topology optimization methods, a customized process planning model is developed for DSLP of monoaxially curved T-section panels. The globally convergent method of moving asymptotes is applied to solve the process planning model. The formed T-section panels, guided by the solution of the process planning model, exhibit good consistency with the objective shape. By unleashing the potential of double-sided laser peening in driving bending, this study provides a novel strategy for forming large-scale complex panels with stiffeners.

Model tests and numerical simulations of deformation repair effect for operating shield tunnels under horizontal lateral grouting

To address the large deformation problem of operating straight-joint assembled shield tunnels in soft soil, horizontal lateral grouting is often used. Using an independently designed and developed lateral grouting test device, a horizontal lateral grouting model test was conducted to study the tunnel force state and deformation repair law under the action of lateral grouting. The mechanical responses of tunnel under single-hole grouting (SHG) and two double-holes grouting (DHG) cases were comparatively analyzed, and the test results were further validated via numerical simulations. The results indicate that several key indicators of tunnel behavior, including additional pressure, bending moment, radial displacement, convergence deformation, and ellipticity, exhibit a positive correlation with the grouting volume and a negative correlation with the distance to the grouting point when implementing SHG. Expect for radial displacement, all of these metrics caused by DHG were greater than those caused by SHG. The horizontal radial displacement increases under same-side DHG but decreases under different-side DHG. Interestingly, same-side DHG is more favorable for reducing internal force and repairing tunnel deformation, and effectively improves tunnel differentiated deformation state along the longitudinal direction. However, different-side DHG can provide a better effect for transverse convergence deformation repair under the premise of minimizing tunnel overall displacement.