Calculation of the T-section Wall Segment for Eccentric Compression (Eccentricity towards the Web)

Objective: Check of the calculation of eccentrically compressed columns.

Task: Verify the correctness of the stability analysis under eccentric compression.

References: Reference manual on design of masonry and reinforced masonry structures (supplement to SNiP II-22-81), 1989, p. 18-19.

Compliance with the codes: SNiP II-22-81, SP 15.13330.2012.

Initial data file:
Example 1.SAV;
ComeIn 1.doc — report

Initial data:

N = 850 kN	Longitudinal force;
М = 102 kN∙m	Bending moment;
Н = 5 m	Storey height;
Stone/brick	Molded clay brick, grade 100;
Mortar	Regular cement with mineral plasticizers, grade 50;
R = 1,5 MPa	Design resistance of masonry;
Н_f = 0,22 m	Thickness of the precast reinforced concrete floor slab, embedded into wall masonry on the supports.

KAMIN initial data:

Importance factor γ_n = 1
Age of masonry - up to a year
Working life is 25 years
Stone/brick - Molded clay brick
Stone/brick grade - 100
Mortar - regular cement with mineral plasticizers
Mortar grade - 50

Structure:

Eccentricity of longitudinal force - 12 cm along the Y axis
Column height 4,78 m
Longitudinal force 850 kN
Factor for sustained load 1

Effective height in the XoY plane	Effective height in the XoZ plane
Bracing scheme Precast floor slabs Distance between transverse rigid structures 5 m Effective height factor 0,9	Bracing scheme Precast floor slabs Distance between transverse rigid structures 5 m Effective height factor 0,9

Effective height in the XoY plane

Effective height in the XoZ plane

Bracing scheme
Precast floor slabs
Distance between transverse rigid structures 5 m
Effective height factor 0,9

Comparison of solutions:

Check	stability in the eccentricity plane
Theory	850/1100 = 0,773
KAMIN	0,757
Deviation, %	2,07

Comments:

The eccentricity of the longitudinal force has to be specified in KAMIN instead of the value of the design moment. Its value is equal to \( e_{0} =\frac{M}{N}=\frac{102}{850}=0,12 \) m.
The column height in KAMIN is taken as the difference between the storey height and the floor slab thickness Н - Н_f = 5 – 0,22 = 4,78 m.
Distance between transverse rigid structures has to be specified in KAMIN. Since it is not determined in the problem, the value of 5 m is used.
Age of masonry and working life have to be specified in KAMIN. Since they are not determined in the problem, the following data are used: "up to a year" and 25 years respectively.
Deviation of the stability factor value in KAMIN from the result of the solution of the problem is caused by the fact that the requirements of Sec. 4.7 of SNiP II-22-81 (Sec. 7.7 of SP 15.13330.2012) for determining slenderness for the compressed part of the section for an alternating bending moment diagram are not taken into account when solving the problem.