b'COIN DES INGNIEURSSection Head: Engineers Corner Coin des ingnieurs de lICCAHead: CISC Engineers Corner Deck: Sway buckling of gusseted connec:ons Byline: Logan Callele, P.Eng. Words: 2548 Flambement latral des assemblages avec goussetIn this edi:on of the Engineers Corner, well be taking a look at the stability design considera:ons used ce C d e le cto evaluate and design gusse n dueel ina es ingnieu ec , nous passeronsn r d 7 foexample.rations relativesla stabilit Danstte ditio ted st obr ce end conn rs :ons, see Figures 1an evue r sonsid Steel projects design es pourdaaluer requirements ofs assemblages9) extrmitt verdi n o onales en acier avec gousset; utilis ed in Cana v to the et concevoir le S16:19 (CSA, 201 d , the curren des sio ag f the standard rvoir les d bures1 et 7 a:onal Bui exemples. se the Canadian column curve, es en acier conus au Canada eferencefigy the latest Npour deslding Code, uPour les projets de charpentEqua:on 1 conformhe compressive strength of steel elemen6. Steel connec:onla versionhave been below, to evaluate tment aux exigences de la normeS1ts:19 (CSA, 2019),designersactuelle de la norme cite par le LOGANCALLELE, ing.bracr end co Code natiocombining S16 nt, on utiliseand the t be i:onal W tance d method designingplus ecentnnec:ons by nal du btimerequirementsla cour radde resis hitmorees pices en compression Directeur de lingnierie for many decade ienne,qu ever, recent re ssous)andurtr valuer la rsistance a needmpresscanad s now. How ation1 ci-de search , po a suctural failure suggestla co to bring ion des lments en acier. CISC-ICCA awareness to an addi:onal stability mechanism that is not typically captured by the tradi:onal Les concepteurs dassemblages en acier conoivent des assemblages dextrmit de contreventement Whitmore checks. en combinant les exigences de la normeS16 et la mthode traditionnelle de Whitmore depuis plusieurs dcennies maintenant. Cependant, des recherches rcentes et une dfaillance structurelle suggrent quil serait ncessaire de diffuser de plus amples informations sur un mcanisme de stabilit supplmentaire The Tradi=onal ApproachWhitmore Method qui nest gnralement pas pris en compte par les contrles traditionnels de Whitmore.Because this method has been described in detail in many other loca:ons (see references) we will only Lapproche traditionnelleMthode de Whitmorebriey summarize the per:nent parts of the method here. The maximum stress in the gusset plate can Comme cette mthode a t dcrite en dtail dans de nombreux autres endroits (voir les rfrences), nous ne rsumerons be es:mated by assuming that the force in the bracing element is transferred uniformly on an area equal ici que brivement les parties pertinentes de la mthode. La contrainte maximale dans le gousset peut tre estime en to the thickness of the gusset plate mul:plied by the Whitmore eec:ve width, again see Figure 1. The supposant que la force dans llment de contreventement est transfre uniformment sur une surface galelpaisseur du designer applies the S16 column curve, Equa:on 1, to this sec:on of the gusset. It might be of interest gousset multiplie par la largeur effective de Whitmore, voir figure1. Pour tablir la rsistancela compression de la plaque for designers to note that the local buckling requirements of Table 1 in S16, which are required to be de raccordementgousset, le concepteur applique lquation 1courbe dinteraction de colonneS16cette section addressed before using Equa:on 1, do not apply to solid sec:ons: i.e. there is no local buckling of a solid du gousset. Il pourrait tre intressant pour les concepteurs de noter que les exigences locales relatives au flambement du sec:on. Thus, when applying the Whitmore method, the stability of the gusset plate can be assessed tableau 1 de la norme S16, qui doivent tre abordes avant dutiliser lquation 1, ne sappliquent pas aux sections pleines; using Equa:on 1 directly without referring to Table 1 in S16:19.c.d. quil ny a pas de flambement local dune section pleine. Ainsi, lors de lapplication de la mthode de Whitmore, la In using the S16 equa:ons, the designer of the gusset connec:on is implicitly modelling the gusset stabilit du gousset peut tre value directementlaide de lquation 1, sans se reporter au tableau 1 de la norme S16:19. stability behaviour, a two-dimensional complex stability problem sensi:ve to the boundary condi:ons of En utilisant les quations S16, le concepteur de lassemblagegoussets modlise implicitement le comportement de the connec:on, as a simpler one-dimensional stability problem. To successfully implement this stabilit de goussets, un problme de stabilit complexe bidimensionnel sensible aux conditions limites du raccordement, simplica:on the designer must assess both the eec:ve width, W w , and the eec:ve length kL, see comme un problme de stabilit unidimensionnel plus simple. Pour russirmettre en uvre cette simplification, le Figure 1. Most connec:on designers use the reference Eec(ve Length Factors for Gusset Plate Buckling concepteur doit valuerla fois la largeur effective, W w , et la longueur effective, kL (voir figure1). La plupart des concepteurs (Dowswell, 2006) for advice on assessing these parameters, and indeed the values noted in Figure 1 are dassemblages utilisent la rfrence Effective Length Factors for Gusset Plate Buckling (Dowswell, 2006) pour obtenir des adapted from this reference as well as Annex F of S16:19.conseils sur lvaluation de ces paramtres. En effet, les valeurs indiquesla figure1 sont adaptes de cette rfrence ainsi Of course, it should also be noted that there are other limit states that would determine the thickness of que de lannexe F de la norme S16:19. the gusset plate, such as yielding considera:on on the Whitmore eec:ve width, W w see Figure 1, Il convient galement de noter quil existe dautres tats limites qui pourraient dterminer lpaisseur du gousset, comme block shear failure, and of course the various brace connec:on fastener limits states (bolts and/or la prise en compte de la largeur effective de Whitmore, W w voir la figure1la rupture par cisaillement des blocs et, bien sr, welds). Informa:on on evalua:ng these other limit states can be found in CISC connec:on design les divers tats limites des pices de fixation de contreventement (boulons ou soudures). Vous trouverez de linformation sur educa:on, see steelstore.cisc-icca.ca. lvaluation de ces autres tats limites dans la formation CISC connections design of steel (voir steelstore.cisc-icca.ca).Equa:on 1: !=AF y 1="(13.3.1.1 of S16) quation 1 # 1+ 2n $ n # ( 13.3.1.1 de la norme S16)where n is typically taken at a value of 1.34, and the slenderness parameter, , is given by Equa:on 2: where n is typically taken at a value of 1.34, and the slenderness parameter, , is given by Equa:on 2: Page 1 of 13 O n reprsente gnralement une valeur de 1,34, et le paramtre dlancement, , est donn par lquation 2 :quation 2 eflambement dEuler, F= .F y ysection de plaque rectangulaire pleine ayantEqua:on 2:Et la contrainte dee e ,.F e pand width W wis: une paisseur, Equa:on 2: = F e FAnd the Euler buckling stress, F , for a solid rectangular plate sec:on of thickness, Tpour uneAnd the Euler buckling stress, F , for a solid rectangular plate sec:on of thickness, T pand width W wis: Equa:on 3:T p , et une largeur, W w , est de : F e= =2E 2E 2" "Equa:on 3:quation 3 F e kL 2= r kL=r 12/ 0 12/ 0We will use an example problem, Figure 6, to illustrate the above, but so far this is all rela:vely common Nhsitez pasposer vos questions sur divers aspects de la conception et de la construction des btiments We will use an example problem, Figure 6, to illustrate the above, but so far this is all rela:vely common knowledge in the steel industry. However, recently there has been discussions about how designers are etdes ponts en acier. Vous pouvez nous les faire parvenir par courrielladresse info@cisc-icca.ca.knowledge in the steel industry. However, recently there has been discussions about how designers are to handle a stability problem characterized by hinge mechanism sway buckling, see Figures 2 - 4 for to handle a stability problem characterized by hinge mechanism sway buckling, see Figures 2 - 4 for examples, and it is to this end that we turn our afen:on for the remainder of this ar:cle. Note: CISC 10|T2024AVANTAGEACIERexamples, and it is to this end that we turn our afen:on for the remainder of this ar:cle. Note: CISC oers no opinion at this :me on the failure of the structure noted in Figure 3 and is developing oers no opinion at this :me on the failure of the structure noted in Figure 3 and is developing educa:on material, such as this ar:cle, to inform designers about this problem so as to avoid similar educa:on material, such as this ar:cle, to inform designers about this problem so as to avoid similar situa:ons in the future. situa:ons in the future.Hinge Mechanism Sway Buckling Hinge Mechanism Sway Buckling An examina:on of Figures 2 - 4 shows the feature that dis:nguishes the Hinge Mechanism Sway Buckling An examina:on of Figures 2 - 4 shows the feature that dis:nguishes the Hinge Mechanism Sway Buckling (HMSB) from the tradi:onal Whitmore buckling/S16 checks, namely a hinge between the connec:on (HMSB) from the tradi:onal Whitmore buckling/S16 checks, namely a hinge between the connec:on paddle plate and the start of the HSS brace. It is this hinge, hinge numbers 2 and 3 in Figure 2, that is paddle plate and the start of the HSS brace. It is this hinge, hinge numbers 2 and 3 in Figure 2, that is not accounted for in the tradi:onal Whitmore buckling check, as that check focuses on the buckling of not accounted for in the tradi:onal Whitmore buckling check, as that check focuses on the buckling of the gusset plate alone, i.e. the Whitmore checks might be thought of accoun:ng for hinge numbers 1 the gusset plate alone, i.e. the Whitmore checks might be thought of accoun:ng for hinge numbers 1 and 4 in Figure 2. Research by Tremblay and Davaran (2020) suggests a dierent model, see Figure 5, and 4 in Figure 2. Research by Tremblay and Davaran (2020) suggests a dierent model, see Figure 5, that would account for two hinges at each brace end to address this situa:on1.that would account for two hinges at each brace end to address this situa:on1.Note that the typical brace design would model and assume that the brace would have a pin at each Note that the typical brace design would model and assume that the brace would have a pin at each end, thus a total of two hinges are assumed in the load path of a typical brace member. This assump:on end, thus a total of two hinges are assumed in the load path of a typical brace member. This assump:on is consistent with how the tradi:onal Whitmore method is applied. However, we will see that the is consistent with how the tradi:onal Whitmore method is applied. However, we will see that the addi:on of further poten:al hinges can also dras:cally decrease the compressive strength of the system addi:on of further poten:al hinges can also dras:cally decrease the compressive strength of the system (member and connec:on) as well. Designers, both connec:on designers and engineers of record, are (member and connec:on) as well. Designers, both connec:on designers and engineers of record, are urged to be aware that there are other situa:ons besides what is covered in this ar:cle where mul:ple urged to be aware that there are other situa:ons besides what is covered in this ar:cle where mul:ple hinges may form. Special care must be taken to adequately address these situa:ons and it is hoped that hinges may form. Special care must be taken to adequately address these situa:ons and it is hoped that a befer understanding of the schema:c model noted in Figure 5 will be of assistance in this regard. a befer understanding of the schema:c model noted in Figure 5 will be of assistance in this regard. The stepped column model shown in Figure 5 is a schema:c of the model proposed by Tremblay and The stepped column model shown in Figure 5 is a schema:c of the model proposed by Tremblay and Davaran (2020) for single lap plate connec:ons of HSS braces. In single lap plate connec:ons there is an Davaran (2020) for single lap plate connec:ons of HSS braces. In single lap plate connec:ons there is an eccentricity, which is very important, but beyond the scope of this ar:cle, see references, and the eccentricity, which is very important, but beyond the scope of this ar:cle, see references, and the connector bolts are in single shear. However, in this case we have a double lap plate HSS brace connector bolts are in single shear. However, in this case we have a double lap plate HSS brace connec:on with the bolts in double shear. Although the double lap plate eliminates the eccentricity, the connec:on with the bolts in double shear. Although the double lap plate eliminates the eccentricity, the same mechanism, hinge numbers 1 and 2 in Figure 2 for instance, applies at each end of the brace with same mechanism, hinge numbers 1 and 2 in Figure 2 for instance, applies at each end of the brace with either connec:on type. An examina:on of Figure 3 shows how the majority of out-of-plane movement is either connec:on type. An examina:on of Figure 3 shows how the majority of out-of-plane movement is Page 2 of 13 Page 2 of 13'