EngSolutions RCB - Eng Solutions Inc

EngSolutions RCB
Analysis & Design of Reinforced Concrete
Buildings for Earthquake and Wind Forces
EngSolutions RCB is a structural engineering-software for 3D analysis and design of reinforced concrete
buildings. EngSolutions RCB consists of several modules integrated into an exceptionally easy to use
software package. Through EngSolutions RCB ’s graphical interface, it is possible to easily create, analyze
and design complex building structures for earthquake and wind forces, according to different building codes.
Creation of the structure, assignment of element properties, definition of supports and application of loads,
are all performed interactively. Hence, there is no need for an input file. Generation of loads is fully
automated releasing the engineer from lengthy manual calculations. Vertical floor loads can be automatically
converted to span loads on adjoining beams and walls. Wind forces and earthquake forces can be generated
automatically according to different international building codes.
Once a building structure is created, the engineer can make changes, such as change coordinates, add or
remove elements, add or remove stories, modify element properties, change support conditions, change
loading, etc., and see the influence of these changes on the analysis and design results. The final building
may be unsymmetrical and arbitrarily irregular in plan. Torsional behavior of the floors and interstory
compatibility of the floors are properly modeled. The solution satisfies complete three-dimensional force
equilibrium and displacement compatibility at the nodes.
Modeling of partial diaphragms, such as mezzanines and openings is possible. It is possible also to model
cases with multiple diaphragms at each level, allowing analyzing buildings consisting of several towers, rising
from a common base structure at the lower levels.
The program allows modeling the incremental construction of tall buildings, checking lateral story drifts,
computing redundancy factors, and designing structural elements according to various seismic codes.
The main technical features of EngSolutions RCB are the following:
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Operation under Windows 8/7/Vista/XP based personal computers
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Automatic generation of seismic forces, static equivalent, spectral, and time-history, according to
numerous international building codes, including: USA ASCE7-2010, ASCE 7-2005, UBC-97, UBC94, ASCE7-93/95, NERPH-97, NERPH-85, Mexico RCDF-2004, GUAD-97, CFE-93, Panama REP04, REP-93, Colombia NSR-10, and NSR-98, Venezuela COVENIN-82, Peru E030-2000, Ecuador
CEC-01 and CEC-93, Chile NCH433.Of93, Dominican Republic R001-2011 and DNRS/SEOPC-80,
Costa Rica CSCR-86, Guatemala AGIES-NSE-10.
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Automatic determination of vertical irregularity type 1a – Soft story
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Automatic determination of vertical irregularity type 1b – Extreme soft story
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Automatic determination of vertical irregularity type 2a – Mass irregularity
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Automatic determination of vertical irregularity type 5a – Weak story
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Automatic determination of vertical irregularity type 5b – Extreme weak story
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Automatic determination of horizontal irregularity type 1a - Torsional irregularity
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Automatic determination of horizontal irregularity type 1b – Extreme torsional irregularity
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Automatic calculation of coefficients for amplification of accidental eccentricity Ax
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Automatic determination of redundancy factors
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Complete library of earthquake records.
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Automatic generation of wind forces, according to various international codes, including: USA
ASCE7-2010, ASCE7-2005, ASCE7-95, ASCE 7- 88, UBC- 94, Mexico RCDF-87, CFE-93,
Dominican Republic DNRS/SEOPC-80.
Reduction of wind forces by the directionality factor and selection of appropriate load factor in the
generation of design load combinations
New equations of resonance and gust factors
Application of accidental eccentricity for modeling non-uniform pressures
Envelope of the solution for several wind load cases
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Accurate modeling of torsion effects: The engineer may specify different design eccentricities based
on inherent and accidental eccentricities, and may choose from different methods of modal
combination available, including SAV, SRSS, CQC, 1/2 SAV+SRSS, and 0.25 SAV + 0.75 SRSS.
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Automatic distribution of floor loads to span loads on adjoining beams and walls. Various floor
systems can be considered, including one-way and two-way slab systems as well as one-way and
two-way joist systems.
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Automated incremental analysis to model the construction sequence of high-rise buildings. Instead of
applying gravity loads in a single step, the analysis can model the sequential addition of floors to the
structure.
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Graphical display of lateral inter-story drifts that allows immediate check for compliance with building
codes.
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New finite element formulations for accurate modeling of buildings with shear walls.
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Automated design of shear-walls, which includes dimensioning of boundary zones for special
(ductile) seismic design.
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Boundary zones for shear walls can be design either according to the stress design method of the
ACI-318-99 or to the strain method of UBC-97 and ACI-318-08/05.
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Automatic generation of design load combinations for elements that support discontinuous vertical
elements and for cases that require the application of overstrength factor Ωo
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Automatic detailing of steel reinforcement for beams.
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Automatic generation of design load combinations according to different international building codes.
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Buildings can be modeled as supported on theoretical dimensionless nodal supports or on rigid
footings, including spread footings for columns, continuous footings for walls, combined footings and
mats.
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Automatic re-sizing of footings according to specified allowable soil pressure.
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Design of spread and continuous footings.
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Specification of member end-releases.
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Automatic generation of load combinations: according to several international codes.
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Structural elements can be separated into elements that are part of the lateral force resisting system
only, elements that are part of the gravity load resisting system and elements are part of both
structural systems.
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Inertia modification-factors for analysis based on cracked sections.
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Design and design check for structural steel members according to the Load and Resistance Factor
Design (LRFD) methods of AISC and RCDF.
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Creation of DXF files.
IDEALIZATION
The EngSolutions RCB building is idealized as an assemblage of column, beam, brace and wall elements,
interconnected by horizontal floor diaphragm slabs, rigid in their own plane. The basic building geometry is
defined with reference to a simple tri-dimensional grid system, formed by intersecting floor planes and
vertical column axes. The building can be at any location and angle with respect to the tri-dimensional grid
system. Column axes are defined through an architectural grid of either, longitudinal and transverse axes, in
the case of rectangular buildings, or radial and circumferential axes, in the case of cylindrical buildings.
Inclined columns and walls can be also modeled displacing their end nodes correspondingly.
Columns, beams and braces are modeled as prismatic elements, which may be subjected to axial and shear
forces and torsion and bending moments. Shear and bending can act in any two perpendicular planes.
Member releases can be specified near the ends of members. The effects of the finite dimensions of the
beams and columns on the stiffness of the structure are automatically included in the analysis.
A panel element is implemented to model general 3D shear wall configurations, such as C-shaped core
elevator walls, discontinuous shear walls, and walls with arbitrarily located openings. Several panel elements
may be used to define a planar or 3D wall.
The panel element is based on the quadrilateral assumed-stress hybrid shell element with rotational or
“drilling” degrees of freedom developed by the National Aeronautics and Space Administration, NASA (M.
Aminpour, NASA Contractor Report 4282, Direct Formulation of a 4-Node Hybrid Shell Element With
Rotational Degrees of Freedom, 1990). In-plane rotational stiffness is modeled implicitly in the formulation of
the element, therefore, any beams or columns that frame into the element in the plane of the wall will receive
full continuity without any special modeling. The panel element allows modeling both, structural walls and
nonbearing walls.
GEOMETRY
Figure 1a. Defining building geometry based on architectural axes. Floor level 2
The EngSolutions RCB software includes Wizards that allow creating complex building structures easily
with minimum user input. The geometry of building models in EngSolutions RCB is based on a grid system
defined by an architectural grid system of axes, which define the plan view of the model, and floor levels,
which define the elevation of the model. This three-dimensional grid is used to define the location of all
structural elements.
Figure 1b. Changing coordinates of nodes on a floor-by-floor basis. Floor level 6
Figure 1c. 3D-view (Faro del Saber Library, Structural Engineer A. Muns, Puerto Rico)
Most building models can be created from a rectangular grid system of longitudinal and transversal axes.
First, an orthogonal grid system is created, by specifying separation between axes. Then the coordinates of
the axis intersections are edited to accommodate the real geometry of the building.
The coordinates of nodes can be varied from floor to floor, allowing the creation of complex tridimensional
building systems with a limited number of axes as shown in Figure 1.
LOADS AND LOAD CASES
Loads in EngSolutions RCB are grouped into load cases. Load cases are independent loadings for which
the structure is analyzed internally, such as dead load (DL), live load (LL), wind load (WL), earthquake load
(EQ), snow load (SL), etc. There can be up to 15 independent load cases.
Loads for any load case can be generated manually through graphical mouse interaction. Manual loads can
be applied to nodes, members and walls.
Loads can also be created automatically. Vertical slab loads can be automatically converted to span loads on
adjoining beams and walls, based on the load properties assigned to each slab. These properties include the
type of floor system, slab thickness, reinforcement direction, superimposed dead load, and values of uniform
live load. The distribution of floor loads is based on tributary areas. Each slab panel is discretized into a grid
of ‘tiles’. The computed slab shears are transformed into equivalent uniformly distributed loads on the
supporting beams and walls. The above procedure is general and can handle irregular slab panels, as well
as slab panels not supported along all its 4 edges.
Wind and seismic loads can be created automatically according to various building codes.
LOAD COMBINATIONS
Load combinations are the loading conditions for which a building structure is designed. Load combinations
are assembled as combinations of the load cases considered. An example of a load combination is: 1.2DL +
1.6LL, where DL is the dead load and LL is the live load.
Once all Load cases to be considered have been generated EngSolutions RCB allows the user to
automatically generate a set of load combinations as required by the selected building codes. There can be
up to 150 load combinations.
ANALYSIS
EngSolutions RCB performs finite element analyses that provide solutions in terms of nodal displacements,
elements internal forces, and moments. The program computes the rigid segments of members to account
for their finite size and computes the buckling loads of columns. The user is allowed selecting 1) the order of
the analysis linear versus P-delta analysis and 2) the analysis type a conventional one-step total
gravity analysis versus an automated incremental step-wise gravity analysis.
EngSolutions RCB performs a Modes/Frequency Analysis that provides the solution for the free vibration
response of the building in terms of its three-dimensional mode shapes and natural frequencies. Mode
shapes, frequencies and modal participation factors are obtained using the Lançzos method with selective
orthogonalization.
EngSolutions RCB allows three types of seismic analyses: static equivalent analysis, spectral analysis, and
time-history analysis.
Figure 2. Time history analysis (Sky Loft Tower, Structural Engineer J. Robert & Associates, Puerto Rico)
Figure 5. Lateral story drift ratio (Sky Loft Tower)
ANALYSIS RESULTS
EngSolutions RCB provides interactive graphic display of analytical results including the static deformed
shape of the building, bending moment diagram, shear force diagram, axial force diagram, torsion moment
diagram, wall internal forces, wall stresses (resultants, mid-plane, front face, back face), support reactions,
shear ratio stress, story drifts, and mode shapes.
Analysis results can be presented for any load case or for any load combination. The displayed results
correspond to the load case or load combination currently active, which is always printed in the EngSolutions
RCB main graphic window. The user may quickly change the active load case or load combination by
clicking with the mouse its label.
EngSolutions RCB also includes a command for the graphical display of story drifts (lateral displacement of
one level relative to the level below), which allows immediate check of compliance with local building codes.
The user may specify a displacement amplification factor to magnify drifts, along with a limit story-drift ratio
(story-drift divided by story-height). The program shows column axes in different colors, depending on
whether or not the amplified relative story drift ratio exceeds the specified limit value.
DESIGNING STRUCTURAL ELEMENTS
Structural elements can be designed in accordance to the Strength Design Method of Building Code
Requirements for Structural Concrete (ACI 318-08/05/02/99) and other international building codes.
EngSolutions RCB computes the required steel reinforcement for any concrete section considering all
design load combinations.
Although EngSolutions RCB is a mainly software for concrete design it includes commands for design and
design check of steel members. The program includes design for various section shapes (W, M, S, T, C, L,
2L, P, etc) created manually or imported from the AISC library, which is included in EngSolutions RCB. The
Steel design command includes command buttons for automatically resizing columns, beams, and braces.
DESIGN RESULTS
The design process is graphically displayed in EngSolutions RCB. Elements are drawn as they are
designed in different colors, depending on the required amount of steel. Elements with insufficient cross
section are marked in red. This way, the designer can clearly see which elements need to be resized. In
addition, EngSolutions RCB computes for all the designed elements, the volume of concrete and weight of
steel required, which allows making cost analyses for various structural solutions.
After the design process is finished, the user can display detailed design results for any element just by
selecting it with the mouse, after activating the Design Results command.
For further information please contact:
EngSolutions, Inc.
At: Ricardo E. Barbosa, Ph.D.
5220 S University Dr., Suite 106C.
Ft. Lauderdale, FL 33328
Tel: (954) 370-6603
Fax: (954) 370-0150
Email: [email protected]
www.engsolutionsRCB.com