Name: eccentric load stresses in structural columns
Uploaded: 2024-05-23T13:00:08.000Z
Duration: 1 min 21 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Physics

PHYS.2

PHYS.2.D

design-of-columns-under-an-eccentric-load

Design of Columns under an Eccentric Load

Para um pilar carregado com uma carga axial excêntrica no plano de simetria, as tensões normais devido à carga excêntrica podem ser escritas como tensões devido a uma carga cêntrica e flexão equivalentes.
Ao projetar colunas com cargas excêntricas, a tensão máxima desenvolvida na coluna não deve exceder a tensão máxima permitida. Essa condição pode ser satisfeita usando duas abordagens distintas.
O método de tensão permitida pressupõe que a tensão permitida para o pilar carregado excentricamente é igual à tensão máxima para o pilar carregado centralmente. A tensão admissível para o pilar pode ser expressa em função da razão de esbelteza.
A tensão permitida para carregamento centrado é menor do que a devido ao momento de flexão. Isso resulta no método de estresse permitido sendo excessivamente conservador. 
Por outro lado, o método de interação considera a tensão permitida devido ao carregamento centrado e à flexão em consideração.
Ele fornece uma equação para a tensão máxima sob carga cêntrica quando não há momento de casal. Da mesma forma, ele define a tensão máxima da flexão pura quando não há carga.

projeto de colunas sob carga excêntrica

Projetar colunas para suportar cargas excêntricas é um aspecto crítico da engenharia estrutural, garantindo que as estruturas possam suportar cargas descentralizadas sem apresentar falhas. Este processo de projeto deve levar em conta as tensões normais adicionais introduzidas pelo carregamento excêntrico, que podem influenciar significativamente a distribuição de tensões e a estabilidade geral de uma coluna. Uma carga excêntrica aplicada a uma coluna induz tensões normais que podem ser concebidas como uma combinação de tensões devidas a uma carga centrada equivalente e tensões de flexão adicionais. Isto leva a uma distribuição não uniforme de tensões que deve ser cuidadosamente analisada para evitar falhas estruturais. Dois métodos principais são empregados no projeto de colunas sob cargas excêntricas: o método de tensão admissível e o método de interação.

O método da tensão admissível é uma abordagem simples onde a tensão admissível para uma coluna carregada excentricamente é igualada à tensão máxima admissível para uma coluna carregada centralmente. Este método simplifica o processo de projeto ao tratar a tensão admissível como uma função do índice de esbeltez da coluna, que é uma medida de sua propensão à flambagem sob carga. No entanto, este método assume que a tensão admissível para carregamento central abrange as tensões adicionais devido à flexão, levando a projetos conservadores que podem não utilizar todo o potencial do material. O conservadorismo inerente a esta abordagem garante a segurança, mas pode resultar em colunas maiores e mais caras do que o necessário.

O método de interação oferece uma abordagem mais sutil, considerando tanto as tensões admissíveis devido ao carregamento central quanto as tensões decorrentes dos momentos fletores. Este método fornece uma estrutura para calcular a tensão máxima que a coluna pode suportar sem um momento binário (carga centrada pura) e a tensão máxima devido à flexão pura (sem carga axial). Ao considerar estas condições simultaneamente, o método de interação permite uma estimativa mais precisa e menos conservadora das tensões admissíveis em colunas carregadas excentricamente.

Na prática, o método de interação é frequentemente preferido pela sua capacidade de equilibrar segurança com eficiência material. Ele requer uma análise detalhada da distribuição de tensões dentro da coluna, considerando tanto as cargas axiais quanto os momentos fletores.

Projeto de Colunas Sob Carga Excêntrica

Para um pilar carregado com uma carga axial excêntrica no plano de simetria, as tensões normais devido à carga excêntrica podem ser escritas como tensões devido a um ...

Education

JoVE Core

Mechanical Engineering

Engenharia Mecânica

Unit 1

Unidade 1

Columns

Colunas

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

eccentric load stresses in structural columns

Structural columns under eccentric load must be designed for both axial force and bending stress. An eccentric load is an off-center load, and it creates a non-uniform stress pattern across the column. Engineers must analyze this stress distribution carefully to reduce the risk of failure.

The stress in an eccentrically loaded column can be treated as the sum of two parts. One part comes from an equivalent centric load, which is a load applied through the center of the column. The other part comes from bending stresses caused by the load being off-center.

Two common design approaches are used for these columns. The allowable stress method sets the allowable stress for an eccentrically loaded column equal to the maximum stress allowed for a centrally loaded column. This method uses the column slenderness ratio, which describes how likely a column is to buckle.

The allowable stress method is simple, but it is also conservative. It assumes the centric-load allowable stress already covers the extra bending stress from eccentric loading. As a result, the column may be larger and more expensive than needed, even though the design is safe.

The interaction method gives a more detailed design check. It considers both the allowable stress from centric loading and the stress from bending moment at the same time. It compares the case of pure centric loading, with no couple moment, and the case of pure bending, with no axial load.

Because it includes both effects, the interaction method can estimate allowable stress more accurately. It is often preferred when engineers want a better balance between safety and material use. The method requires careful stress analysis of the column under both axial load and bending moment.

Eccentric Load Stresses in Structural Columns

eccentric-load-stresses-in-structural-columns

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euler&#39;s formula for pin-ended columns

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euler&#39;s formula to columns with other end conditions

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Euler Buckling for Different Column Supports

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euler&#39;s formula to columns: problem solving

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Spring-Loaded Column Buckling Analysis

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eccentric loading

Column Bending Under Off-Center Load

Eccentric loading shows how a column bends when a force is applied off-center. In structural engineering, this matters because the load no longer acts along the centroidal axis, so the column sees both direct compression and bending stress. The off-center force can be treated as two parts. One part is a centric load F that acts along the column’s axis. The other part is a couple moment created by the eccentricity, or distance, between the load and the centroidal axis. To study the column...

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Column Buckling and Load Design Basics

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design of columns under an eccentric load

Structural columns under eccentric load must be designed for both axial force and bending stress. An eccentric load is an off-center load, and it creates a non-uniform stress pattern across the column. Engineers must analyze this stress distribution carefully to reduce the risk of failure. The stress in an eccentrically loaded column can be treated as the sum of two parts. One part comes from an equivalent centric load, which is a load applied through the center of the column. The other part...

key terms and concepts

Learn how eccentric loads create combined axial and bending stresses in columns, and compare the allowable stress and interaction methods used in design.

Eccentric Load Stresses in Structural Columns | JoVE K12

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Eccentric Load Stresses in Structural Columns

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