Alejo, Janssen Paul T. 13 October 2015

CE/3 – 2012103567 CE132P/B3

Homework 1 – Determinate and Indeterminate Structures

I. Differences Between Determinate and Indeterminate Structures

Determinate Structures Indeterminate Structures

Equilibrium conditions are fully adequate to analyze the structure.

Conditions of equilibrium are not adequate to fully analyze the structure.

Bending moment or shear force at any section is independent of the material property of the structure.

Bending moment or shear force at any section depends upon the material property.

The bending moment or shear force at any section is independent of the cross-section or moment of inertia.

The bending moment or shear force at any section depends upon the cross-section or moment of inertia.

Temperature variations do not cause stresses. Temperature variations cause stresses.

No stresses are caused due to lack of fit. Stresses are caused due to lack of fit.

Extra conditions like compatibility of displacements are not required to analyze the structure.

Extra conditions like compatibility of displacements are required to analyze the structure along with the equilibrium equations.

II. Advantages of Indeterminate Beam

1. Smaller Stresses – in statically indeterminate structures, the maximum stress is greatly lower

compared with statically determinate structures.

2. Greater Stiffness – statically indeterminate structures have higher stiffness than determinate

structures. Stiffness means the capacity of a structure to bend hence, statically indeterminate

structures have lower deflection.

3. Redundancies – statically indeterminate structures have the capacity to redistribute loads in

case of sudden structural failures caused by accidents such as tornadoes, earthquakes, typhoons,

etc. This is due to its more number of members and/or support compared with statically

determinate structures.

III. Disadvantages of Indeterminate Beam

1. Stresses Due to Support Settlements – support settlements have negligible impact in

determinate structures however, when support settlements are subjected to indeterminate

structures, bending of the structure is inevitable and therefore bending moments are present in

the beam.

2. Stresses Due to Temperature Change and Fabrication Errors – temperature change and

fabrication errors does not significantly affect determinate structures but in terms of

indeterminate structures, its effects are more noticeable and must be accounted and designed

with care.

IV. Examples of Determinate and Indeterminate Structures

1. Determinate Structures

a. Simply Supported Beam

b. Cantilever

2. Indeterminate Beam

a. Continuous Beam

b. Propped Beam

c. Restrained Beam

V. References

1. BIBLIOGRAPHY Kassimali, A. (2011). Structural Analysis 4e. Stamford, CT: Cengage

Learning.

2. Mishra, G. (n.d.). Determinate and Indeterminate Structure. Retrieved from The Constructor:

http://theconstructor.org/structural-engg/analysis/determinate-and-indeterminate-

structures/3483/