News

February 2019

News and updates in BETONexpress 26.02.2019:

Arch design has been added

progetto archi c.a.

progetto archi


November 2018

    Improvements in the geotechnical design.

    Also many adjustments in the report and the computations according to the National annexes.


March 2018

Aggiornamenti alle nuove normative Italiane DM2018. Neve, vento.

Implementate anche molte migliorie nelle relazioni e nei calcoli secondo gli Annessi Nazionali.


November 2016

New features in BETONexpress 07.11.2016:

Set specific reinforcement

Sometimes, in concrete elements the reinforcements chosen by the program to satisfy the design in Ultimate Limit State (ULS), is not enough for the max crack or max deflection criteria of in Serviceability Limit State (SLS). To take this into account, a new option has been added.  

In all the design objects: plates, beams, columns, footings, retaining walls, you can now specify the desired reinforcement.

If you do not check the Set specific reinforcement, the program computes the reinforcement as usual.
If the box is checked, you can specify the reinforcement more than needed for maximum moment in ULS. This reinforcement is used for the additional checks in Serviceability Limit State (SLS), and reinforcement schedules.

Set specific reinforcement

Punching shear for plates and flat slabs

Option for circular columns

 Punching shear for pates and flat slabs

Soil bearing capacity in fundaments and retaining walls

If the box EC7 Annex D is checked, the soil bearing capacity is computed from Annex D of Eurocode 7. The computations are done simultaneously as you change the dimensions of the structure.

Soil bearing capacity in fundaments and retaining walls

Columns Crack width calculation 

If the box Calculation of crack width is checked, the crack width wk is calculated. The load in SLS is computed from the Loading ration (ULS/SLS).

Columns Crack width calculation


June 2015

New features in BETONexpress 05/2015:

·   Flat slab, Punching shear

·   Flat slab design

·   Foundation Bearing resistance

·   Fundaments of Steel columns

·   Water basins

·   Basement walls

·   Bearing walls

·  Walls with horizontal distributed load 

Flat slab, Punching shear

piastre piane

Slab section in Punching shear

The design of slab section in punching shear according to Eurocode 2 6.4. Verification of the shear capacity at the control perimeters around a rectangular column. If the design shear Ved exceeds the shear capacity Vrd,c, the program computes the necessary shear (links) reinforcement.

Sezione piastra a taglio-punzonamento

Input values.

  Shear force Ved on the column face.

  • Longitudinal reinforcement over the column, in x and y directions.
  • Specify with Yes or No if you want to use shear reinforcement or No. If Yes then the appropriate shear reinforcement will be comptuted if the shear force βVed>Vrd,c.
  • Column dimensions
  • Column position (internal, edge or corner.

 

Punching shear reinforcement.

If is cchecked No for shear reinforcement the punching shear is checked so βVed<=Vrd,c. If it is not satisfied a message to increase the slab thickness is shown. If the shear reinforcement is checked YES then peripheral reinforcement is computed around the columns.

The selected diameter for the reinforcement is used. If not enough a higher reinforcement diameter is selected.

For shear reinforcement the minimum number of perimeters is 3.

The radial spacing of links does not exceed 0.75d.

The tangential spacing of links does not exceed 1.5d  within the 2d distance of the column face.

The first shear perimeter is at distance <0.35d of the column face.

The last perimeter is at distance 1.5d inside the outer perimeter where shear reincorcement is no longer required. Eurocede 2 Eq. 6.54.  and Fig. 6.22

Flat slab design

Design of flat slab with inner span dimensions Lx Ly, and end span dimensions Lx’ and Ly’.

Specify Yes or No if you want to use shear reinforcement. If Yes then the appropriate shear reinforcement will be computed if the shear force βVed>Vrd,c.

Progetto Piastre piane

 

Analysis

The analysis for moment and shear forces is based on coefficients of continuous beams.

Method 1:

          inner spans

             Support moments: Ms= (0.083·γG·g+0.111·γq·q)·L2/8

             Span moments   : Mf= (0.063·γG·g+0.075·γq·q)·L2/8.

          End spans

             Support moments: Ms= (0.125·γG·g+0.125·γq·q)·L2/8

             Span moments   : Mf= (0.080·γG·g+0.096·γq·q)·L2/8

Method 2:

         inner spans

             Support moments: Ms= (0.083·γGxg+0.083·γq·q)·L2/8

             Span moments   : Mf= (0.063·γGxg+0.063vγq·q)·L2/8.

          End spans

             Support moments: Ms= (0.111·γG·g+0.111·γq·q)·L2/8

             Span moments   : Mf= (0.077·γG·g+0.077vγq·q)·L2/8

Method 3 Table 3.1 BS8110

          Inner spans

             Support moments: Ms= (0.063·γG·g+0.063·γq·q)·L2/8

             Span moments   : Mf= (0.063·γG·g+0.063·γq·q)·L2/8.

          End spans

             Support moments: Ms= (0.086·γG·g+0.086·γq·q)·L2/8

             Span moments   : Mf= (0.086·γG·g+0.086·γq·q)·L2/8

The support bending moments are reduced by (1-cx/Lx) 2 and (1-cy/Ly) 2 for x and y direction

The span  bending moments are reduced by (1-cx/Lx) and (1-cy/Ly) for x and y direction

Shear forces

  Corner columns Ved=0.25·(Lx’+cx)·(Ly+cy);

  Edge columns   Ved=0.50·(Lx’+cx)·Ly;

  Inner columns  Ved=1.25·Lx·Ly;

The bending moments of the flat slab panels, are apportioned in column and middle strip according to Eurocode 2 Annex I, as follows

Negative moments: column strip 70%, middle strip 30%

Positive moments: column strip 55%, middle strip 45%

The column strip in both x and y direction is equal to min(Lx,Ly)/2.

 

Punching shear reinforcement.

If is checked No for shear reinforcement the punching shear is checked so βVed<=Vrd,c. If it is not satisfied a message to increase the slab thickness is shown. If the shear reinforcement is checked YES then peripheral reinforcement is computed around the columns.

The selected diameter for the reinforcement is used. If not enough a higher reinforcement diameter is selected.

For shear reinforcement the minimum number of perimeters is 3.

The radial spacing of links does not exceed 0.75d.

The tangential spacing of links does not exceed 1.5d  within the 2d distance of the column face.

The first shear perimeter is at distance <0.35d of the column face.

The last perimeter is at distance 1.5d inside the outer perimeter where shear reinforcement is no longer required. Eurocode 2 Eq. 6.54.  and Fig. 6.22

 

Foundation Bearing resistance

The basis for the design of foundations is the bearing resistance of the soil.

Capacità portante delle Fondazioni

The design bearing resistance may be calculated using analytical or semi empirical methods. Annex D of Eurocode 7 EN1997:2004 describes a method of obtaining the design bearing strength of the soil.

Capacità portante delle Fondazioni

The methods of Annex D for drained and undrained conditions are implemented in the program.

The Design bearing strength of the soil is estimated for EQU, STR and GEO conditions.

The computation of design bearing strength is for drained and undrained soil conditions. For drain soil conditions the important soil property is the angle of shearing resistance φk [°] and the cohesion intercept c[kPA]. For drained soil conditions the important soil property is the undrained strength cu [kPa].

For the computation of design bearing strength other parameters are the dimensions and foundation depth of the footing, as well as the loading and the load eccentricities. 

 

In the foundation design of the program for the soil strength we use the soil bearing pressure quk (N/mm2). This is a corresponding soil strength to the soil allowable pressure. In the foundation design we use as Design bearing soil pressure qud=qukqu, where gqu is the partial factor for unconfined strength. (Eurocode 7, Annex A). So to be consistent the convert the design strength estimated from Annex D of Eurocode7 to the soil bearing pressure used in the program the design value have to  be multiplied by γqu.

Is γqu =1.40 for EQU and 1.00 and 1.4 for (STR-GEO).

Click ico in the design of fundaments or in the design of retaining walls, and you get into a calculation window for design bearing resistance.

There you have an estimate of the soil bearing resistance quk which you may use in the program, from the soil and fundament parameters.

If there you check to include the calculations in the report, then the design bearing resistance will be set to the minimum estimated and the calculations  will be included in the report of the footing design. (remember that if you alter the dimensions or loading you have to re-evaluate quk).

Fundaments of Steel columns

Plinti per pilastri d’acciaio

The concrete footing of steel structures has to be designed to resist soil pressure for maximum vertical load, and it must have enough weight to resist uplift (from wind or seismic forces).

You can design Pin and Fixed end Column foundations.

You can also specify if the foundation has an horizontal tie to take the horizontal outwards forces or not

 

Loading on the fundament:Carichi sulle fondazioni

The final actions after multiplication with safety factors (γG and γQ). Eurocode-19990-1-1, Tabl.A1.2

For download loading usual γG =1.35(unfavourable), γQ=1.50.

For uplift loading usual  γG =0.90(favourable), γQ=0.00.

The height over the foundation surface of the load application must be specified.

 

 

Steel Tie and Passive earth pressure

 

The high horizontal forces acting at the base are acting outwards as a result of bending in the columns due to vertical loading on the roof.


This is resisted in two ways:

  • Steel tie at column base A tie cast into the floor slab connected to the base of the columns. This should be considered more safe method to resist the horizontal forces at the base of the columns .

Tirante in acciaio

  • Passive earth pressure on the side of the foundation. In this case the earth filling and compacting on the side of the foundation must be performed carefully, so that the passive earth pressure is not reduced. The fundament transverse width By and the height Bh are used to compute the active area for passive earth pressure.

Spinta passiva del terreno

If you pressed the predimensioning button pulsante predimensionamento , the foundation dimensions (if not checked) are adjusted by the program so the fundament weight is enough to resist uplift forces. The width By and the height are also for adequate passive earth force to resist the horizontal base force outwards.

 

Water basins

calcolo serbatoi

The design is for rectangular water basins. The solution is for a 2-Dimensional cross section across the smallest dimension (width) of the basin.

The basic dimensions are the width of the basin B [m] (1),  the length of the basin L [m](2), and the depth of the basin H [m]( (3).

The basin assumed to sit on elastic ground and is analysed with finite element analysis. The basin walls are subdivided in 2 beam elements of length H/2. The basin floor is modelled with 16 beam elements with nodal points connected to the ground with elastic springs. The stiffness of the elastic springs is computed from the Winkler foundation modulus Ks [kN/m2/m] (4).

The loading conditions include all the load cases according to Eurocode0, (EQU, STR, and GEO) for

  • empty water basin (only earth pressure),
  • filled water basin without earth pressure
  • filled water basin with earth pressure.   

The reinforced concrete design includes also serviceability control, with limit crack width specified in (5).

Basement walls

Muri di ritegnoMuri di ritegnoMuri di ritegnoMuri di ritegno

Basement walls are walls which are built in basements. They are two kinds of these walls.

  • Walls with only the bottom restrained for lateral movement,
  • Walls with restrained the bottom and the top for lateral movement

 

In the first case the sliding of the wall is prevented due to the retraining of the base in movement. The active earth pressure is computed as usual using Coulomb(1776) or Rankine (1857) theory. Eurocode 7 9.5.1. 

In the second case (when the wall top is also prevented from lateral movement), the active earth pressure conditions are obtained for Ko in rest conditions according to Jaky(1948) , Eurocode 7 9.5.2.

 

Bearing walls

Muri portantiMuri portantiMuri portanti

Bearing walls in vertical or horizontal load on the top without any earth pressure.

The horizontal load on the top can be defined from Eurocode 1-1-1:2001 Table 6.12

According to national annexes, and the use of the building Usual values qk~ 0.50 to 1.00 (kN/m2)

The horizontal load on the top can be also defined according to Eurocode 1-1-7:2006, In case of Impact load

 

Walls with horizontal distributed load

Pareti con carico orizzontale distribuito

 

In case of wind loading the wind pressure is according to Eurocode1-1-4:2005

 

qw=0.001 Cpe·Cz(0)·0.625·vb2, (kN/m2)

 

Cpe:pressure coefficient for vertical wall,

According to Table7.1 EN1991-1-1,

  Cpe=+0.80 (pressure) at front wall surface)

  Cpe=-1.20 (suction ) at the back face of  the wall

  Cz(0) exposure coefficient, depending on the terrain. For various terrains  according to 1991-1-1 4.5 for ground level Cz(0) is between 1.20 and 2.00.

Vb is the basic wind velocity in m/sec. This is given in the National Annex of Eurocode 1-1-4, for various regions of a country. Common values of Vb between 25 and 40 m/s

So an estimate of the wind loading on a wall is about

qw~0.001x(0.80+1.20)x2.0x0.625x30.02~ 2.25 kN/m2

 

Foundaments of steel structures

 

Foundament of Pin column bases

 

Foundaments of fixed column bases

 

Anchoring of steel column base plate

 

 

 

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