- masonry design according to Eurocode6,
- concrete design according to Eurocode 2
- foundation design according to Eurocode 7
- seismic design according to Eurocode 8
- roof design according to Eurocode 5
The Design of the masonry buildings is
based on the assumption that the maximum part of the vertical and horizontal loads are
taken from the masonry.
The design of concrete floors in vertical loading is performed considering the beams as
space grillage. The live loads are placed on the spans to obtain the worse loading
conditions. The concrete slabs are solved using the Marcus method.
The horizontal seismic forces on each
floor are considered as equivalent static loads. The floors are
assumed to act as horizontal stiff diaphragms. For the distribution of the seismic forces
on the walls, the stiffness of each wall is computed using finite element
The wall stresses are computed by
finite element analysis of each wall on its plane. These
stresses are used for the strength checks according to Eurocode 6.
If some checks for the
masonry are not verified
they will appear with red font in the reports. In
that case you must change masonry dimensions or materials, or masonry mortar
topology of slabs, the surrounding beams and walls, the shape and elements needed for the
slab analysis are automatically recognised by the program expert system. The user has
complete overview of the topology and all the analytical computations in the reports. The
design of concrete slabs is based on the Marcus method.
In masonry building, in most cases, the plate arrangement is simple
and almost orthogonal. In that case the solution using the Marcus method produces
satisfactory results. This method is based on the solution of unit plate strips located at
mid spans, with equal deflections at the plate center. From this assumption the
plate load distribution in the two main directions is obtained. The advantage of the
plate torsional resistance is not taken into account. Each plate strip is solved as a
continuous beam. The solution is obtained through specific coefficients, which are
obtained from the solution of continuous beams of equal spans. These coefficients are
considered having such values as to obtain the maximum internal forces. The minimum
(maximum in absolute value) support bending moments are obtained using the most
unfavourable position of live loads in an equivalent continuous beam. The maximum (minimum
in absolute value) support moments are obtained using the most favourable position of the
live loads. From these support moments the maximum span moments are obtained using
span loading 1.35g+1.50 q.
The loads transferred on the beams and the walls are
obtained by loading with live loads both slabs on the left and right side of the beam or
wall. In the case of slabs with span ratio over 2, or load factor <0.10, the load is
transferred only in one direction. In this case the beams which doe not take load from the
slab are loaded with a minimum uniform load equal to wL/4, where w=1.35g+1.50q. (g,q dead
and live load of the plate, L the beam span).
The design for ultimate strength is done according to Eurocode 2
§4.3.1. The design for serviceability conditions is base on control of the slenderness
ratio (EC2 §18.104.22.168). In addition the minimum steel reinforcement requirements are
verified. The minimum cover for steel reinforcement is set to 20 mm which satisfies the
code requirements (EC2 §22.214.171.124) for dry or humid environment.
The concrete floor beam system is designed as a system of beam grid.
The structural analysis is done with finite elements. The finite elements are beams with 3
degrees of freedom per node, rotations around x-x and y-y axis and vertical displacement
along the z-z axis. The grid is supported on the walls and the columns. When the wall is
not parallel to the beam axis the rotations are zero. For the computation of the beam
stiffness the effective flange width is taken 0.70L/10 for each beam flange (left or
The solution is done for unit uniform loads on each span of
the grid. The most unfavourable load combinations are obtained with combination of the
results of the unit loads (1.35g and 1.50 q). The solution is performed using Gauss method
for symmetric banded matrices.
The dimensioning of beams is according to Eurocode 2. For the design
the support bending moments are taken at a distance 10 cm from the support (wall or
column) axis. The design shearing force values are taken at a distance d (beam height)
from the support face (EC2 §126.96.36.199). The effective flange width is taken 0.70L/10 for
each beam flange left or right. The minimum reinforcing steel coverage is set to 50 mm
that satisfies the code requirements (EC2 §188.8.131.52) for dry or humid environment. Only
straight reinforcing steel bars are used for main reinforcement, and the shear force is
taken only with vertical stirrups. The minimum requirements for steel reinforcement are
verified. The verification of crack width requirements and maximum deformations are done
according to (EC2 §4.4.2).
| Masonry Walls
The masonry walls are carrying most of the
vertical and all the horizontal loads.
The computation of the horizontal
seismic forces for each floor level is based on equivalent static loads. The floors are
assumed to act as horizontal stiff diaphragms. The vertical distribution of the seismic
loads is "reverse triangular". The horizontal seismic force acts at the mass
center of each floor. The center of rigidity of each floor is computed using the stiffnesses of the walls at each floor. The wall stiffness depends on the wall
dimensions and the dimensions and positions of the openings. The wall stiffness is computed with a
finite element analysis of each wall, for unit relative displacement between the top and
bottom wall ends. The eccentricity between the rigidity center and the center of mass of
each floor is taken into account, in the distribution of the horizontal seismic forces on
the walls. After the computation of the horizontal loads the evaluation of the internal
stresses of the walls is also done with a finite element analysis, for the various load
The slenderness ratio check is performed based on Eurocode 6 §184.108.40.206. The
effective height of the wall is taken hef=ñh h. The coefficient ñ is
computed for partial or complete restrain on the top and bottom of the wall and we
consider ñ3=ñ4=1 for vertical wall edges, as most unfavourable.
The shear verification is done according to Eurocode 6 §4.5.3.
the applied shear load (horizontal
force per unit length). It
is obtained from the results of finite element analysis (excluding stress concentrations
at beam supports).
The maximum compressive stresses obtained from finite element analysis at the
places of beam supports are verified according to §4.4.8 to be less than fk/fM.
The building foundation is assumed in the same ground level. All the footings are
connected in both directions with foundation beams. The minimum width of foundation is
computed according to Eurocode 7.
The Finite Element method
With the finite
element method a continuum with infinite number of degrees of freedom is approximated with
a discrete system of elements connected only at a finite number of nodal points. The
solution of the problem is reduced to a discrete number of equations, from which the
unknown values at the nodal points are obtained.
The method of finite elements has
founded in the end of 1950 by Argyris, Turner and Clough. After that an increasable number
of theoretical work and computer programs together with the rapid developments in computer
power made the finite element method a powerful tool of analysis in all the branches of
In the program we use plane stress
quadrilateral elements with four nodes. The finite mesh is obtained automatically keeping
an element ratio (width to height) less than 2. The solution algorithm and the accuracy of
the results have been checked with other well established programs, SAPIV, STRUDL.
Which Buildings can be designed with
program you can design buildings, for which the major part of the loads is taken from the
masonry. All the horizontal seismic forces are taken from the masonry. There may exist
some columns from reinforced concrete but they do not take any seismic loads. The
stiffness of the columns is negligible compared with the masonry wall stiffness.
The shape of the building must be simple and the shape of the slabs about
You enter only the bearing walls, not the non-bearing separation walls.
Codes that are applied
The dimensioning of the concrete elements (slabs, beams, columns, footings)
is based on Eurocode 2. The masonry dimensioning is based on Eurocode 6. The timber
roof design is based on Eurocode 5. The load evaluation and action combinations are based
on Eurocode 1.
The foundation design is according to Eurocode 7. The seismic forces are
computed according general acceptable methods in most seismic design codes and Eurocode 8.
designed with the method of Marcus. Non-orthogonal slab shapes must be avoided.
Beams are designed as space grid.
On the top and along each masonry wall, and on top of the openings, we assume
the existence of small concrete beams that are taking the small tension stresses.
The columns must have orthogonal cross section, with about equal dx and dy
dimensions. Long columns must be replaced with masonry elements. The columns are designed
in biaxial bending and the reinforcing steel is considered symmetric on each column side.
Footings are considered as centric footings. Some small moments are taken from connecting
you cannot do
You cannot have columns on top of slabs, beams, or walls. A column must continue with a
2) You cannot have a wall under two walls or a wall on top of two walls. A wall
must have a wall underneath.
3) You cannot have flat slabs.