An Assessment of Flexural Improvement of Light Weight Concrete via Hybrid Fibres along with Sisal Fibres in Addition to Banana Fibres

Innate fibres, these days have become the topic of argument in the research field between different scientists to inculcate it in the formation of lightweight concrete mixture. This is due to a variety of rewards connected with natural fibres like recyclable, economical, availability in large quantity and its bio-degradability. Plenty of projects have been carried out in the production of natural fibre reinforced lightweight concrete. In this project, we would like to take the naturally existing fibre named sisal fibre and banana fibre as partial replacement material. The adding of natural fibre to the lightweight concrete will enhance the diverse strength parameters like flexural strength, compressive strength, and increase the ductile behaviour. In the current work, it is intended to explore the mechanical properties of lightweight concrete with substitution of sisal fibre and banana fibre for cement in different percentages. The compressive strength, flexural strength, deflection of the beam is calculated with the reflection of M30 concrete specimens. Totally 45 number of 500 x 100 x 100mm flexural member, 45 numbers of cubes and 45 numbers of cylinders are cast and tested. It is suggested that up to 1.5% substitution of sisal fibres and banana fibre with cement provide at M30 grade of concrete giveing the most beneficial increases of strength values. The assessment outcome indicated that the sisal fibres and banana fibre were efficient in improving the performance of lightweight concrete

Random Forest versus Support Vector Machine Models’ Applicability for Predicting Beam Shear Strength

The shear and bending are the actions that are experienced in the beam owing to the fact that the beam is a flexural member due to the load in the transverse direction to their longitudinal axis. The shear strength (Vs) computation of reinforced concrete (RC) beams has been a major topic in the field of structural engineering. There have been several methodologies introduced for the Vs prediction; however, the modeling accuracy is relatively low owing to the complex characteristic of the resistance mechanism involving dowel effect of longitudinal reinforcement, concrete in the compression zone, contribution of the stirrups if existed, and the aggregate interlock. Hence, the current research proposed a new soft computing model called random forest (RF) to predict Vs. Experimental datasets were collected from the open-source literature including the related geometric properties and concrete characteristics of beam specimens. Nine input combinations were constructed based on the statistical correlation to be supplied for the proposed predictive model. The prediction accuracy of the RF model was validated against the Support Vector Machine (SVM), and several other empirical formulations have been adopted in the literature. The proposed RF model revealed better prediction accuracy in addition the model structure emphasis in the incorporation of seven predictors by excluding (beam flange thickness and coefficient). In the quantitative term, the minimal root mean square error value was attained (RMSE = 89.68 kN).

Reliability Analysis of Flexural Deflection of Reinforced Concrete Members under Ultra-Low Temperature

Based on the Monte Carlo method, the functional function under the normal use limit state given by the specification introduces the concrete tensile strength of each temperature gradient under ultra-low temperature, and the coefficient of change of concrete elastic modulus. By changing the temperature of the member, the thickness of the protective layer, the bending moment effect ratio, the reinforcement size,the concrete grade and the length of the bending beam. Analyze the reliable index of the deflection control of the flexural member under ultra-low temperature to obtain: When the reinforced concrete flexural member is reduced from normal temperature 20°C to-160°C, the reliable deflection index of the component increases non-linearly, reaches the maximum value at-130°C, and then decreases slightly, the concrete strength grade and the thickness of the protective layer under each temperature gradients have the greatest influence on the deflection control of the bending beam under ultra-low temperature, followed by beam length, steel bar size, load effect ratio,which is different from normal temperature.

Calibrating a New Constitutive Tension Model to Extract a Simplified Nonlinear Sectional Analysis of Reinforced Concrete Beams

Nonlinear analysis of structural members is vital to understand the behavior and the response of reinforced concrete members. Even though most design procedures concentrate on the ultimate stage of response towards the end of the post-yielding zone as the decisive design criterion, the structural members usually function at the service load levels within the post-cracking zone. Therefore, cracking is a critical aspect of concrete behavior that affects the overall response of reinforced concrete beams. The initiation and the propagation of the cracks are affected directly by the tension and shear stresses in the beam. In flexural beams, the tensile stresses dominate the crack onset and its growth. Cracks in reinforced concrete flexural beams leave non-cracked regions in between the cracked sections. In order to apply a consistent analysis strategy, the smeared crack approach averages the behavior of these different cracked sections and uncracked in between regions to generate an accurate global response of the entire beam. This study presents a numerical constitutive tensile model that captures the complete tensile response of the reinforced concrete flexural member, in terms of averaged/smeared crack response. As a second step, this model was examined against a large pool of experimental data to validate its accuracy. Overall, the main objective of this study is to develop a representative constitutive tensile model for reinforced concrete flexural members and validate its accuracy against experimental results. The full nonlinear sectional response is analytically realized, based on the assumed trilinear moment–curvature response and the assumed trilinear moment–extreme fiber compressive strain response. This is considered as the secondary outcome of the present study.

Steel I-joists calculating method with the heel joint partial restraint

Steel joists in general, are widely used in modern building practice and I-joist systems in particular. That is why close attention to the structural concept development or joist construction is paid. That would significantly reduce the material consumption, including changing the flexural member strain-stress distribution. The classic pin joint for supporting steel joist involves a bolted connection in the lower third of the knife-edge height. The constructive solution considered in this article contains additional requirements for the heel joint: tight installation clearance filling between two adjacent joist knife-edges, bolt installation that satisfy the strength condition. These requirements ensure the tensile force transfer from a couple of forces emerging on the pier. We proposed a method for calculating steel I-joist, with the account of the obtained partial restraint effect. This method developed based on numerical calculations of three-dimensional finite element beams models using the binodal unilateral connection, however, with proper justification, the results transfer to the core design schemes. Modeling and calculations are performed in the SCAD Office computer complex. The steel I-joist floor beams studied in this paper have 15 m spans. The restraining effect is estimated based on a results comparison of finite element models numerical calculations of a single joist and two adjacent simultaneously working steel joists. Joist test models are made using shell finite elements with zero Gaussian curvature. As the study result of the operation compatibility of the joist structures heel joint and the analysis of the system strain-stress distribution, a moment redistribution from the span to the heel joint was revealed. With the increase in the span, the restrain effect was found fading. The partial restrain accounting method allows us to assign more economical sections during similar structures designing, due to the introduction of binodal unilateral connection in the heel joint of the joist numerical models. This technique can be used for verification calculations during the technical examination. This paper shows that the bolt junction sections selection for connecting steel joists on a pier can be performed according to the reactions obtained in unilateral connection. Using this calculation methodology in practice for actual construction design provides an opportunity to increase the joist systems’ efficiency and reliability that part of constructional buildings and structures complex.

A Novel Compliant Bistable Mechanism Incorporating a Fixed-Guided Flexural Member

This paper presents the design of a novel compliant bistable mechanism. Bistable mechanisms are commonly used in switches and other devices that operate in two distinct modes. This mechanism is a single monolithic structure with simple geometry and does not require external components or post-manufacture assembly. As such, the design is ideally suited for additive manufacturing at large, or micro, scales. The design features a fixed-guided flexural member with surrounding geometry. When a load is applied to the mechanism in a stable configuration, the flexural member exhibits an inflection point that enables bifurcated behavior. As a result, the mechanism snaps between two stable positions in an on-off operation mode. This paper describes the mechanism geometry and its operation. Preliminary design modeling equations are formulated. A finite element simulation is presented that verifies the design equations. Lastly, a prototype is presented to confirm the operation and facilitate force and displacement measurements.