Axial shortening during pachynema unrelated to nonhomologous synapsis

The orthogonal experimental design was conducted for linear friction welding of Ti-6Al-4V titanium alloy (TC4). The friction power and joint temperature were collected during the welding process. The influence of process parameters on the axial shortening was analyzed. The suitable process parameters were determined by investigating the joint appearance, the requirement of axial shortening and welding variables during welding. The results provide important reference for establishing process parameters of linear friction welding in practice.

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A comparative study on the differential axial shortening in high‐rise buildings

Structural Concrete ◽

10.1002/suco.202100053 ◽

2021 ◽

Author(s):

Rafael Ruiz ◽

Leonardo Todisco ◽

Alfredo Pazos ◽

Hugo Corres

Keyword(s):

Comparative Study ◽

High Rise ◽

Axial Shortening

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Infrastructure Sustainability

Rethinking Sustainable Development - Advances in Environmental Engineering and Green Technologies ◽

10.4018/978-1-61692-022-7.ch014 ◽

2011 ◽

pp. 202-211

Author(s):

Praveen Moragaspitiya ◽

David Thambiratnam ◽

Nimal Perera ◽

Tommy Chan

Keyword(s):

Numerical Procedure ◽

Time Dependent ◽

Test Procedures ◽

High Rise ◽

Secondary Systems ◽

Content Variable ◽

True Time ◽

And Performance ◽

Concrete Elements ◽

Axial Shortening

High density development has been seen as a contribution to sustainable development. However, a number of engineering issues play a crucial role in the sustainable construction of high rise buildings. Non linear deformation of concrete has an adverse impact on high-rise buildings with complex geometries, due to differential axial shortening. These adverse effects are caused by time dependent behaviour resulting in volume change known as ‘shrinkage’, ‘creep’ and ‘elastic’ deformation. These three phenomena govern the behaviour and performance of all concrete elements, during and after construction. Reinforcement content, variable concrete modulus, volume to surface area ratio of the elements, environmental conditions, and construction quality and sequence influence on the performance of concrete elements and differential axial shortening will occur in all structural systems. Its detrimental effects escalate with increasing height and non vertical load paths resulting from geometric complexity. The magnitude of these effects has a significant impact on building envelopes, building services, secondary systems, and lifetime serviceability and performance. Analytical and test procedures available to quantify the magnitude of these effects are limited to a very few parameters and are not adequately rigorous to capture the complexity of true time dependent material response. With this in mind, a research project has been undertaken to develop an accurate numerical procedure to quantify the differential axial shortening of structural elements. The procedure has been successfully applied to quantify the differential axial shortening of a high rise building, and the important capabilities available in the procedure have been discussed. A new practical concept, based on the variation of vibration characteristic of structure during and after construction and used to quantify the axial shortening and assess the performance of structure, is presented.

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Time-dependent deformations of concrete columns under different construction load histories

Advances in Structural Engineering ◽

10.1177/1369433219828133 ◽

2019 ◽

Vol 22 (8) ◽

pp. 1845-1854 ◽

Cited By ~ 1

Author(s):

Dujian Zou ◽

Chengcheng Du ◽

Tiejun Liu ◽

Jun Teng ◽

Hanbin Cheng

Keyword(s):

Prediction Models ◽

Plain Concrete ◽

Concrete Columns ◽

In Situ Monitoring ◽

Time Dependent ◽

Construction Stage ◽

Inappropriate Use ◽

High Rise ◽

Multi Stage ◽

Axial Shortening

The adverse effects caused by differential axial shortening in high-rise buildings have received increasing attention with growing building height. However, the axial shortening analysis still lacks accuracy compared to the in-situ monitoring results of practical high-rise buildings during construction stage. It is imperative to identify the error sources, and the applicability of the current shortening prediction models should be test verified. In this study, 14 plain concrete columns were cast, and the multi-stage load method was applied to approximately simulate the loading history of axial concrete members during construction stage. The time-dependent deformations of loaded concrete specimens were measured, and a comparative analysis was conducted between test results and numerical prediction values. It is found that the measured deformations of multi-stage loading cases are all underestimated compared with predicted results, and this underestimation may be mainly caused by the inappropriate use of elastic modulus. It further indicates that the axial shortening analysis of high-rise buildings tends to underestimate the actual shortening value when the traditional calculation method is used. This study provides a reference for explaining the mismatch between the analytical results and the actual shortening values.

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