Wood and armer method wood and armer proposed one of the most popular design methods that explicitly incorporate twisting moments in slab design. The original source is the paper the reinforcement of slabs in accordance with a predetermined field of moments, rh wood, concrete, february 1968, and a followon letter from gst armer, concrete, april 1968. H the reinforcement of slabs in accordance with a predetermined field of moments, concrete, february 1968, august 1968 correcpondence, 6976. It contains important information that may be more current than what is in the manuals. Wood the reinforcement of slabs in accordance with a predetermined field of moments, concrete, fevrier 1968, aout 1968 correspondance. The nodal method in this case is giving excessively conservative reinforcement under the core walls.
The wood and armer equations are well established as a means of accounting for torsional moments in bridge slabs. In this article, a potential source of misinterpretation of the original. Application qf these equations will lead, in many cases, to an improved assessment for bridges previously analysed using the wood armer equations and found to require a load restriction. Twisting moments in twoway slabs design methods for torsion in slabs using finite element analysis. Tn328 design for twisting moments in adaptfloor pro wood armer method tn338 temperature effects in multistory buildings.
The design moments are commonly referred to as woodarmer wood. The wood armer method is a way of optimising reinforcement design in a reinforced concrete slab. Method of calculating plate and shell reinforcement area. Manual for design and detailing of reinforced concrete to the.
Technical note a brief dialog on woodarmer and twising. This method was developed by considering the normal moment yield criterion johansens yield criterion aiming to prevent yielding in all directions. Wood armer method allows moment triads from plates mx, my, mxy to be transformed into simple bending moments in two directions wood armer moments for reinforcement design of plate elements. Woodarmer moments these are moments to be resisted by each layer of reinforcement calculated according to the published equations, which allow designers to make allowance for plate bending and twisting moments when designing the reinforcement within a reinforced concrete panel. Wood armer moments for reinforcement design of plate elements. The conception of determining equivalent moment is authored by wood and armer. I am trying to verify this by hand using aci318 design code. Oct 04, 20 extraction of slab design wood armor moments for rebar calculation. Yield line analysis and the woodarmer equations both use as. By using woodarmer moments in midas civil, accurate reinforcementquantities can be calculated.
The woodarmer equations also optimise the total area of reinforcement. Introduction whichever method is used to determine the moment distribution in a slab or plate, the next problem confronted is normally that of how to ensure that the strength of the plate is adequate to resist the calculated moments. The following are methods of determining reinforcement of plates and shells. Steel section optimisation as per eurocode 3 composite section capacity check as per eurocode 4. Pdf twisting moments in twoway slabs design methods for. The woodarmer equations also optimise the total area of reinforcement required in the slab in all four layer s, and p ro vide t he r equ ired be nd ing r esist anc es in t he re info rce ment. Manual for design and detailing of reinforced concrete to.
About wood armer method of incorporating twisting moments denial structural 18 oct 18. Orthogonal or skew reinforcement may be considered. The application is referred to as woodarmer procedure. Effect of skew angle on distribution of bending moments in. For uls, both bending only using wood armer, and bending and inplane effects using clarknielsen can be considered.
The wood armer equations also optimise the total area of reinforcement required in the slab in all four layer s, and p ro vide t he r equ ired be nd ing r esist anc es in t he re info rce ment. Introduction the woodarmer equations were derived for the design of reinforced con. On applying the necessary loads and boundary conditions, the wood armer moments could be checked graphically as well as in form of table. Design of reinforced concrete slabs 105 2 shears vx and vv 3 wood armer moments mxt, mxb, mvt and m 4 inplane loads nx and iv method 1. The lack of a provision for twisting moments in the wood and armer method design of slabs does not necessarily make the code wood and armer5 proposed. Woodarmer moments can be calculated forany direction of reinforcement in the top and bottom facesof slabs. Slab design by wood armer method free download as pdf file. This problem may be viewed as one of knowing how to. Wood armer method allows moment triads from plates mx, my, mxy to be. Manual for design and detailing of reinforced concrete to the september 20 code of practice for structural use of concrete 20 2.
Explicit extraction of twisting moments is neither necessary, nor practiced. But if an estimate of isting moments is made then it can be included in the design following woodarmer equations. Pro v8i, the latest version, allows civil engineering individuals to analyze structural designs in terms of factors like force. Wood armer moment of bottom rebars for positive moments. Effect of mxy on design of a slab spreadsheet microsoft. The wood armer equations 1,2 were devel oped to sati sfy th e normal m oment yi eld cri terion, whi ch re qui res th at th e m omen t m n norma l to the n axis see equati on 1 m ust b e. The woodarmer method is a structural analysis method based on finite element analysis used to design the reinforcement for concrete slabs.
The above table shows that spreadsheet wa moments can be more than summary wood armer moments 23 16 march 2011. I have gone through the derivation of this method in journals and we are stuck with respect. Question 2 if the recognition and inclusion of twisting moments mxy is not done explicitly for serviceability check of a floor slab, then where is it used. Wood armer moment calculation is one of the most popular design methods that explicitly incorporate twisting moments in slab design. May 19, 20 regarding wood armer, e, so looks like ill just have to make a spreadsheet to convert the staad plate output table into wood armer moments i need for concrete design. About wood armer method of incorporating twisting moments about wood armer method of incorporating twisting moments nimish07 structural op 17 oct 22.
The wood armer equations also optimise the total area of reinforcement. Safe key features and terminology flexural, shear, and torsion design of beams punching shear checks and punching reinforcement design dynamic analysis of floor systems and foundations by exporting response spectrum analysis results from etabs to safe design for twisting moments. This new torsion design option allows the designer to use the woodarmer approach to handle twisting moments in slabs. Details concerning the method can be found, for instance, in r.
Tn343 aci 318 code interpretations of spantodeflection ratios. For an irregular hypothetical slab as shown below, the wood armer moment result in the direction of reinforcement i. As a general mesh is now possible and strips can be arbitrarily placed, only the woodarmer method is available for obtaining the design moments. As a result, the design moments used for the determination of reinforcement are somewhat larger than the actual bending moments generated in the slab the design uses the program adapt floor pro release 20092010 featuring the hong kong code. Load case 1 position woodarmer moments knmm reinforcement mm. By using wood armer moments in midas civil, accurate reinforcementquantities can be calculated. According to cca 2 the orthogonal mesh is cumbersome in input data but the output moments result mx, my and mxy can be used directly in the woodarmer equations as in hambly 3 to calculate the steel required in any direction therefore, it is preferable to have orthogonal grillage unless the transverse steel is in the skew direction. The reinforcement of slabs in accordance with a predetermined field of moments, concrete, v. This method provides simple equations to design a concrete slab based on the output from a finite element analysis software. About wood armer method of incorporating twisting moments. The reinforcement of slabs in accordance with a pre determined field of moments, concrete, v. Introduction the wood armer equations were derived for the design of reinforced con. You can plot absolute twist, as shown in the figure, plotting results in chapter 30.
Sep 03, 2011 design of reinforced concrete slabs 105 2 shears vx and vv 3 woodarmer moments mxt, mxb, mvt and m 4 inplane loads nx and iv method 1 bs8110. Remarks on methods of calculating plate and shell reinforcement. A brief dialog on wood armer and twising moments in floor slab design1 bijan o aalami2 preliminary draft september 23, 2012 one method for floor slab design combines the twisting moment mxy with the direct moments mxx, or myy to arrive at the strength condition moment, and use this moment to determine the required reinforcement. To provide this torsion design options, a new cross section analysis quantity, absolute twist, is calculated.
Appendix c, foundation capacities tables, provides design capacities for foundation uplift and withdrawal, based on the foundation type chosen wood, concrete masonry or cast. In the design of reinforced concrete slabs the woodarmer equations. One method for floor slab design combines the twisting moment mxy with the direct moments mxx, or. The woodarmer method is a structural analysis method based on finite element analysis used.
Application qf these equations will lead, in many cases, to an improved assessment for bridges previously analysed using the woodarmer equations and found to require a load restriction. The assessment of reinforced concrete slabs istructe. Woodarmer moments and reinforcement for each load case. Wood armer moments these are moments to be resisted by each layer of reinforcement calculated according to the published equations, which allow designers to make allowance for plate bending and twisting moments when designing the reinforcement within a reinforced concrete panel. Wood armer is useful because it allows moment triads from grillages mx, my, mxy to be transformed into simple bending moments in two directions for reinforcement design. Mat displacements and woodarmer ram staad opentower. Comparison of wood armer calculations using the summary versus the spreadsheet the values stand for the design values after considering the twisting moment. All these methods are based on the use of moments per unit length, m. I know that wood armer method is the bestused method for handling twisting moments in slab.
Myy to arrive at the strength condition moment, and. Appendix b, foundation design load tables, provides design requirements for anchorage of the manufactured home to the foundation and recommended footing sizes. Design of reinforced concrete slabs 105 2 shears vx and vv 3 woodarmer moments mxt, mxb, mvt and m 4 inplane loads nx and iv method 1 bs8110. Pro is one of the most widelyused software for developing and analyzing the designs of various structures, such as petrochemical plants, tunnels, bridges etc. Tn352 cracking moment and determination of ieff in adaptbuilder. Regarding woodarmer, e, so looks like ill just have to make a spreadsheet to convert the staad plate output table into woodarmer moments i need for concrete design. Method of calculating plate and shell reinforcement wood. This new torsion design option allows the designer to use the wood armer approach to handle twisting moments in slabs. P152advances structural mechanicsdavid johnson design moments. Wood, the reinforcement of slabs in accordance with a predetermined field of. Enter the rotational angle with respect to gcs xaxis. Yield line analysis and the woodarmer equations both use as a yield criterion the stepped or normal moment yield criterion. These new design moments allow the mxy moment to be considered when designing the section. Strand7 reinforced concrete design capabilities post.
For sls, both bendingonly using principal moments, and bending and inplane effects using principal stresses can be considered, if supported by a chosen design code. Wood armer moment of top rebars for negative moments. Extraction of slab design wood armor moments for rebar calculation. The misinterpretation is shown not to have significant implications for design, but may be of consequence where the wood and armer equations have been used for. Since plate theory indicates that the m12 moment is 0 for uniformly loaded circular plates the moment should be the same as the principal m1 moment. This is important because the twisting moment mxy can be significant. Wood, the reinforcement of slabs in accordance with a predetermined field of moments. In the general case, the design moments used for the determination of reinforcement are somewhat larger than the actual bending moments generated in the slab when the woodarmer approximation of the program is invoked.
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