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

Per una colonna caricata con un carico assiale eccentrico nel piano di simmetria, le sollecitazioni normali dovute al carico eccentrico possono essere scritte come sollecitazioni dovute a un carico centrico e a una flessione equivalenti.
Durante la progettazione di colonne con carichi eccentrici, la sollecitazione massima sviluppata nella colonna non deve superare la sollecitazione massima ammissibile. Questa condizione può essere soddisfatta utilizzando due approcci distinti.
Il metodo della sollecitazione ammissibile presuppone che la sollecitazione ammissibile per la colonna caricata eccentricamente sia uguale alla sollecitazione massima per la colonna caricata centralmente. La sollecitazione ammissibile per la colonna può essere espressa in funzione del rapporto di snellezza.
La sollecitazione ammissibile per il carico centrico è inferiore a quella dovuta al momento flettente. Ciò fa sì che il metodo delle sollecitazioni consentite sia eccessivamente conservativo. 
D'altra parte, il metodo di interazione considera la sollecitazione ammissibile dovuta al carico centrico e alla flessione.
Fornisce un'equazione per la massima sollecitazione sotto carico centrico quando non c'è un momento di coppia. Allo stesso modo, definisce la sollecitazione massima dalla flessione pura quando non c'è carico.

 progettazione di pilastri soggetti a carico eccentrico

La progettazione di colonne in grado di resistere a carichi eccentrici è un aspetto critico dell'ingegneria strutturale, poiché garantisce che le strutture possano supportare carichi decentrati senza cedimenti. Questo processo di progettazione deve tenere conto delle sollecitazioni normali aggiuntive introdotte dal carico eccentrico, che possono influenzare in modo significativo la distribuzione delle sollecitazioni e la stabilità complessiva di una colonna. Un carico eccentrico applicato ad una colonna induce sollecitazioni normali che possono essere concettualizzate come una combinazione di sollecitazioni dovute ad un carico centrico equivalente e sollecitazioni di flessione aggiuntive. Ciò porta ad una distribuzione non uniforme delle tensioni che deve essere attentamente analizzata per prevenire cedimenti strutturali. Nella progettazione di colonne soggette a carichi eccentrici vengono utilizzati due metodi principali: il metodo delle tensioni ammissibili e il metodo dell'interazione.

Il metodo delle sollecitazioni ammissibili è un approccio semplice in cui la sollecitazione ammissibile per una colonna caricata eccentricamente è equiparata alla sollecitazione massima ammissibile per una colonna caricata centralmente. Questo metodo semplifica il processo di progettazione trattando la sollecitazione ammissibile come una funzione del rapporto di snellezza della colonna, che è una misura della sua propensione a deformarsi sotto carico. Tuttavia, questo metodo presuppone che la sollecitazione ammissibile per il carico centrico comprenda le sollecitazioni aggiuntive dovute alla flessione, portando a progetti conservativi che potrebbero non sfruttare tutto il potenziale del materiale. Il conservatorismo insito in questo approccio garantisce la sicurezza ma può dar luogo a colonne più grandi e costose del necessario.

Il metodo di interazione offre un approccio più sfumato considerando sia le sollecitazioni ammissibili dovute al carico centrico sia le sollecitazioni derivanti dai momenti flettenti. Questo metodo fornisce un quadro per il calcolo della sollecitazione massima che la colonna può sopportare senza un momento di coppia (carico centrico puro) e la sollecitazione massima dovuta alla flessione pura (senza carico assiale). Tenendo conto di queste condizioni simultaneamente, il metodo d’interazione consente una stima più accurata e meno conservativa delle tensioni ammissibili nelle colonne caricate eccentricamente.

In pratica, il metodo dell’interazione è spesso preferito per la sua capacità di bilanciare la sicurezza con l’efficienza dei materiali. Richiede un'analisi dettagliata della distribuzione delle tensioni all'interno della colonna, considerando sia i carichi assiali che i momenti flettenti.

 Progettazione di pilastri soggetti a carico eccentrico

Per una colonna caricata con un carico assiale eccentrico nel piano di simmetria, le sollecitazioni normali dovute al carico eccentrico possono essere scritte come sollecitazioni dovute a un carico ...

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JoVE Core

Mechanical Engineering

Ingegneria Meccanica

Unit 1

Unità 1

Columns

Colonne

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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 to columns with other end conditions

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eccentric loading

Column Bending Under Off-Center Load

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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.

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Eccentric Load Stresses in Structural Columns

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