Failure Mechanisms and Parameters of Elastoplastic Deformations of Anchorage in a Damaged Concrete Base under Seismic Loading

The article addresses mechanisms of anchorage failure in a concrete base studied within the framework of physical experiments. The authors investigated the most frequently used types of anchors, such as the cast-in-place and post-installed ones. The anchorages were studied under static and dynamic loading, similar to the seismic type. During the experiments, the post-earthquake condition of a concrete base was simulated. Within the framework of the study, the authors modified the values of such parameters, such as the anchor embedment depth, anchor steel strength, base concrete class, and base crack width. As a result of the experimental studies, the authors identified all possible failure mechanisms for versatile types of anchorages, including steel and concrete cone failures, anchor slippage at the interface with the base concrete (two types of failure mechanisms were identified), as well as the failure involving the slippage of the adhesive composition at the interface with the concrete of the anchor embedment area. The data obtained by the authors encompasses total displacements in the elastic and plastic phases of deformation, values of the bearing capacity for each type of anchorage, values of the bearing capacity reduction, and displacements following multi-cyclic loading compared to static loading. As a result of the research, the authors identified two types of patterns that anchorages follow approaching the limit state: elastic-brittle and elastoplastic mechanisms. The findings of the experimental research allowed the authors to determine the plasticity coefficients for the studied types of anchors and different failure mechanisms. The research findings can be used to justify seismic load reduction factors to be further used in the seismic design of anchorages.

An Investigation of Bearing Capacity of High-Strength SRC Columns under Eccentric Axial Load

This paper investigates the eccentric compression performance of high-strength steel reinforced concrete (SRC) columns. In addition, the feasibility of the calculation codes used for the load-carrying capacity of these columns is verified by eccentric compression tests on 10 high-strength SRC columns with Q460 and Q690 steels and two normal SRC columns with Q235 steel. Moreover, the influence of the steel strength, relative eccentricity, steel ratio, and stirrup spacing on the bearing capacity and ductility of the specimens is analyzed. It was found that the bearing capacity and ductility of the specimens significantly increases when the steel strength increases from 276.5 MPa to 774.2 MPa; the bearing capacity of the Q690 SRC column is slightly higher than that of the Q460 SRC column. In addition, the ductility coefficient of the Q690 SRC columns is significantly higher than that of the Q460 SRC columns. It was also found that increasing the eccentricity and steel ratio can improve the ductility of the specimens and the smaller stirrup spacing can enlarge the contribution of Q690 steel under the ultimate bearing capacity. It is demonstrated that Eurocode 4-2004 and AISC360-16 codes significantly underestimate the test results. In contrast, JGJ138-2016 slightly underestimates the test results when the relative eccentricity is 0.2 but overestimates the test results when the relative eccentricity is 0.6. Furthermore, in order to maximize the contribution of Q690 steel under ultimate bearing capacity, the expanded parameter analysis is carried out using a finite element model. Following the analysis results, the suggestions for designing high-strength SRC columns under eccentric load are provided.

Finite Element Analysis on Behavior of Reinforced Hollow High Strength Concrete Filled Square Steel Tube Short Columns under Axial Compression

Hollow concrete-filled steel tubular (CFST) member is mainly adopted in power transmission and transformation structures, but when it is used in the superstructure with complex stress, the hollow CFST member has a low bearing capacity and is prone to brittle failure. To improve the mechanical performance of hollow CFST members, a new type of reinforced hollow high strength concrete-filled square steel tube (RHCFSST) was proposed, and its axial compression performance was researched. 18 finite element analysis (FEA) models of axially loaded RHCFSST stub columns were established through FEA software ABAQUS. The whole stress process of composite columns was studied, and parametric studies were carried out to analyze the mechanical performance of the member. Parameters of the steel strength, steel ratio, deformed bar and sandwich concrete strength were varied. Based on the simulation results, the stress process of members can be divided into four stages: elastic stage, elastoplastic stage, descending stage and gentle stage. With the increase of steel strength, steel ratio, the strength of sandwich concrete and the addition of deformed bars, the ultimate bearing capacity of members also increases. Additionally, the increment of those parameters will improve the ductility of the member, except for the sandwich concrete strength.

A Straightforward Procedure for Deriving the Biaxial Interaction Diagrams of RC Sections in Fire

Based on the lower bound static approach of the yield design (or limit analysis) theory, this contribution presents a straightforward computational procedure for establishing the biaxial interaction diagrams of RC sections in fire conditions, taking into account the experimentally-based relationships linking the degradation of material strength properties to the temperature increase. In the present approach, material characteristics are introduced in two steps: (i) a preliminary heat transfer analysis for evaluating the temperature distribution on the RC section and (ii) the introduction of reduced factors as functions of temperature into both the concrete and steel strength properties. For illustrative purpose, calculations will be conducted on a typical RC section subjected to different fire exposures. Finally, the theoretical predictions will be compared to those obtained from numerical simulations using a finite element software.

Wind Analysis of a Multi Storied Structure

Due to growing population and less availability of land, multistoried buildings are constructed which can serve many people in less area. Purpose of this project is to analysis and designs (G+13) multistory building using E-TABS. Aims are to give proper awareness regarding right design and details of the building. Planning is done using AutoCAD, Designs has involves Load calculations, manually and the Structure is analysis using E-TABS. Codes refer for these projects are NBC IS (456-2000). Concrete mix use is M30. The steel strength for all members is of grade Fe-415 & Fe500. For analyzing the structure, the loads are very important which are calculated using IS (875). The LIMIT STATE METHOD is the method which has been adopted. The manual design is a difficult process and consumes more time. The project purpose is to give the overall experience in the field of planning, design and to gain the knowledge in a practical way.

Analisis Kekuatan Kolom Beton Bertulang Berdasarkan Diagram Interaksi Kolom

The column interaction diagram is a boundary area graph showing the various combinations of axial loads and moments that the column can safely hold. The benefit of a column interaction diagram provides an overview of the strength of the column in question. This study aims to analyze rectangular and circular columns using column interaction diagrams and then compare the strength of the columns in withstanding a combination of axial loads and bending moments with the same area. In this study, square and circular columns have the same number of reinforcement, diameter of reinforcement, steel strength, concrete quality, and cross-sectional area. The column is reviewed based on five conditions, namely pure axial load conditions, pure bending moment, and three failure conditions. Based on the five conditions that occurred, a column interaction diagram was created by using Microsoft Excel. Results of the analysis show that in the same area, the square column is stronger in withstanding the bending moment (Mu) of the circular column by 0.015 - 0.61%, while the circular column is stronger in resisting the axial force (Pu) of the square column by 1,9 - 4.4%.

Simulation Analysis and Experimental Study on the Working State of Sinking Headframe in the Large Underground Shaft

Based on the newly developed sinking headframe for the deep and large shaft, the finite element model of the full-scale headframe was established by using SAP2000. Through the calculation, the theoretical stress of the headframe at sinking depths of 40 m, 143 m, 223 m, 518 m, 762 m, 1000 m, 1250 m, and 1503 m was obtained and then compared with the field measured stress. The results show that with the increase of shaft sinking depth, the theoretical stress of finite element simulation and the field measured stress of each member of the sheave wheel platform and the headframe increase linearly, and for the maximum member stress in the upper, middle, and lower layers of the headframe, the numerical simulation value is greater than the field measured value and less than the designed steel strength. In other words, under normal working conditions, headframe members are in the elastic stress stage and meet the design requirements, and instability failure of headframe members will not occur. The end-restraint mode of the supporting bars has a great influence on the force of the top member. The reasonable selection of the restraint mode in the simulation is the key to the accuracy of the calculation results. The simulation results well reflect the actual stress of the headframe and provide a reliable guarantee for the follow-up work of the project.

A Review on Wind Analysis of a Multi Storied Structure

Due to growing population and less availability of land, multistoried buildings are constructed which can serve many people in less area. Main aim of this project is to analyse and design a (G+16) multistory building using E-TABS. Aims to give proper awareness regarding right design and details of the building. Planning is done using AutoCAD. Design involves load calculations manually and the structure is analyzed using E-TABS. Codes refer for this project are NBC IS (456-2000). Concrete mix use is M30. The steel strength for all members are of grade Fe-415. For analyzing the structure, the loads are very important which are calculated using IS (875). The LIMIT STATE METHOD is the method which has been adopted. The manual design is a difficult process and consumes more time. The project purpose is to give the complete experience in the field of design and to gain the knowledge in a practical way.

Dual rolls equal channel extrusion as unconventional SPD process of the ultralow-carbon steel: finite element simulation, experimental investigations and microstructural analysis

The paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain refinement.