MANUFACTURING & INSTALLATION GUIDELINES & GUIDE SPECIFICATIONS for STRUCTURAL PRECAST

Transcription

1 MANUFACTURING & INSTALLATION GUIDELINES & GUIDE SPECIFICATIONS for STRUCTURAL PRECAST CONTENTS: 2 Mnufcturing Tolernces 4 Instlltion Tolernces 5 Definitions

2 FABCON DESIGN GUIDELINES FOR PRECAST CONCRETE WALL PANELS Fbcon is committed to construction innovtion nd sfety. Through continuous improvement in qulity nd efficiency, Fbcon delivers high qulity products nd services of exceptionl vlue. This document provides guidelines for designing precst concrete wll pnels to Fbcon s mnufcturing nd instlltion tolernces. Bsed hevily on the qulity control mnul for precst nd prestressed concrete plnts published by the Precst/Prestressed Concrete Institute (PCI) MNL 116, these tolernces reflect Fbcon s unique mnufcturing processes nd ptented products. As designer, mnufcturer nd instller of precst products, Fbcon delivers complete wll pnel system. These tolernces represent our cceptble mnufcturing nd instlltion guidelines. They do not represent n exhustive criteri for rejection. These guidelines re intended s reference for licensed designers nd construction professionls. Nothing in these guidelines shll relieve the designer of record from responsibility for the structure s design nd proper interfce of the precst pnel system with the building structure. Fbcon is not responsible for deficiencies in building design. REMEDIES - Fbcon my elect one or more of the following solutions: - Bring the product into tolernce by industry-stndrd repir methods. - Provide clcultions tht demonstrte tht the product/instlltion meets cceptble structurl nd rchitecturl performnce criteri. - Demonstrte tht the completed systems meets cceptble structurl nd rchitecturl requirements or offer modifictions to meet design requirements. Due to the inherent nture of concrete, hydrtion, hndling, nd shipping of precst, some chipping nd or crcking my occur. Product my require routine finishing such s blending for texture nd color fter instlltion. Fbcon bses our scope of work on completed wll pnel system nd specificlly excludes project specifictions grnting the unilterl right to reject product tht is correctble utilizing stndrd industry repir methods or cn be demonstrted to meet structurl nd/or rchitecturl performnce criteri. FABCONPRECAST.COM 1 VersCore+Green WALL PANEL MANUFACTURING TOLERANCES FABCON = LENGTH...± ½" [± 13mm] b = WIDTH (overll)...± ¼" [± 6mm] b 1 = WEB WIDTH The totl web width defined by the sum of the ctul mesured vlues of b 1 shll not be less thn 85 percent of the sum of the nominl web widths b 1 nominl c = DEPTH (overll)...± ¼" [± 6mm] c 1 = TOP FLANGE DEPTH Top flnge re defined by the ctul mesured vlues of verge c 1 x b shll not verge less thn 85 percent of the nominl re clculted by c 1 nominl x b nominl... ¾" [ 18mm] c 2 = BOTTOM FLANGE DEPTH Bottom flnge re defined by the ctul mesured vlues of verge c 2 x b shll not be less thn 85 percent of the nominl re clculted by c 2 nominl x b nominl... ¾" [ 18mm] d = VARIATION from Specified Pln End Squreness of Skew...± ⅛" per 12" width, ± ½" mximum...[± 3mm per 300 mm width, ± 13mm mximum] e = VARIATION from Specified Elevtion End Squreness or Skew...± ⅛" per 12" [± 3mm per 300 mm] f = SWEEP...± ⅛" per 20", ±⅜" mximum...[± 3mm per 6m, ± 10 mm mximum] k 1 = LOCATION OF STRAND Perpendiculr to Plne of Pnel...± ¼" [± 6mm] MNL116 k 2 = LOCATION OF STRAND Prllel to Plne of Pnel...± ½" [± 13mm] l 1 = LOCATION of Embedment...± 1" [± 13mm] l 2 = TIPPING nd Flushness of Embedment FABCON...± ¼" [± 6mm] l 3 = CONCRETE Surfce Between Embedments to Receive Continuous Ledger, Reltive to Plne of Embedments... - ¼", + 0" [- 6mm, + 0mm] n 1 = LOCATION of Blockouts...± 1" [± 25mm] n 2 = SIZE of Blockout...± ½" [± 13mm] p = LOCATION of Inserts for Structurl Connections...± 1" [± 25mm]* *for further detils contct your Sles Engineer t 1 = SIZE of Architecturl Feture...± ¼" [± 6mm] t 2 = LOCATION of Architecturl Feture...± ¼" [± 6mm] x = WEIGHT...Actul mesured vlue shll not exceed 110 percent of the nominl published unit weight used in the design. i = BOW...Length/360 mximum i 1 = DIFFERENTIAL BOWING Between Adjcent Pnels of the Sme Design...± ½" [± 13mm] j = WARP...± 1 /16" per foot [± 1.5mm per 300mm] MNL116 Concrete is vrible mteril. Even fter finl finishing, there will be rnge of color nd texture in the surfce. Some vritions re to be expected. Tolernces shown should be considered s guidelines for n cceptble rnge nd not limits for rejection. If these tolernces re met, the unit should be ccepted. If these tolernces re exceeded, the unit my still be cceptble if it meets ny of the following criteri: 1. Exceeding the tolernce does not ffect the structurl integrity of the unit. 2. The unit cn be brought within tolernce by structurlly stisfctory mens. 3. The totl erected ssembly cn be modified to meet ll structurl requirements. 2 FABCONPRECAST.COM ± 1 ± ½" ± ⅛" ± ⅛

3 FABCON WALL PANEL MANUFACTURING GUIDELINES SUPPLEMENT to PCI VersCore+Green WALL PANEL FIELD INSTALLATION TOLERANCES FABCON b Building grid dtum d d b g f h q = LOCATION of opening...± ¼" [± 6mm] r = HEIGHT of opening...+ ¾", - ¼" s = WIDTH of opening...+ 1", - ½" s r q q i 1 PLAN Steel structure of Steel structure Footing 10-0 e e c SECTION Building elevtion dtum 10-0 h 10 NOMINAL JOINT WIDTH ELEVATION k 1 k 1 k 1 k 1 k 2 t 2 e t 1 b 1 l 1 l 2 b CROSS SECTION ELEVATION c 1 c c 2 c 1 c c 2 l 3 n 2 n 1 PROFILE r = Pln loction from building grid dtum... ± ½" 1 = Pln loction from centerline of steel support... ± ½" b c d = Top elevtion from nominl top elevtion; Exposed individul pnel... ± ½" Non-exposed individul pnel...± ¾" Exposed reltive to djcent pnel... ± ½" Non-exposed reltive to djcent pnel...± ¾" = Support elevtion from nominl elevtion: Mximum low... ½" Mximum high... ¼" = Mximum plumb vrition over height of structure or over 100 ft. whichever is less*... ± 1" *For precst buildings in excess of 100' tll tolernces nd d cn increse t rte of ⅛" (3mm) per story to mximum 2" (50mm). e = Plumb in ny 10 ft. of element height...± ¼" f = Mximum jog in lignment of mtching edges... ± ½" g = Joint width (governs over joint tper)...± ⅜" g 1 = Form Side...½" ± ⅜" g 2 = Top Fce Side... ¾" ± ⅜" g 3 = Top Fce Side... ⅞" ± ⅜" h = Joint tper over height...± ¾" ½ h 10 = Joint tper over 10 ft. height... ± ⅜" i j = Mximum jog in lignment of mtching fces: FABCON Exposed to view... ± ⅜" Not exposed to view... ± ¾" = Differentil bowing or cmber s erected between djcent members of the sme design... ± ½" MNL135 Formed side of pnel Top, tooled side of pnel Culking my look slightly wider due to rdiused, chmfered or tooled edges. Formed side of pnel Top, tooled side of pnel TYPICAL PANEL JOINT Culking my look slightly wider due to rdiused, chmfered or tooled edges. g 2 g 1 g 1 = NOMINAL, 1/8 to 7/8 inclusive of tolernces Chmfered edge from pllet Rounded edges from tooling = NOMINAL, 1/8 to 7/8 inclusive of tolernces Chmfered edges from pllet Rounded edges from tooling TYPICAL PANEL JOINT d n 1 p f The recommended erection tolernce vlues re those to which the member primry control surfces re to be set. It is the position dimensions of the primry erection control surfces which should be controlled during erection. The remining position dimensions of the member fetures nd secondry control surfces of the member will be the result of the combintion of the erection tolernces nd the pproprite product tolernces. Erection nd product tolernces for some fetures of precst concrete member my be dditive. FABCONPRECAST.COM 3 PLAN 4 FABCONPRECAST.COM

4 DEFINITIONS PLANT - PRECAST STRUCTURAL CONCRETE PANELS CAMBER The deflection tht occurs in prestressed concrete members due to the net bending resulting from the eccentricity of the prestress force. Length of bow Exposed fce Length of bow PART 1 - GENERAL CLEARANCE Interfce spce (distnce) between two elements. Clernce is normlly specified to llow for the effects of product nd erection tolernces nd for nticipted movement (e.g. deflection, therml movement). COVER The lest distnce between the surfce of the reinforcement nd the surfce pproximtes plne. CROSS SECTION CONVEX BOWING Mx. bowing CROSS SECTION CONCAVE BOWING Mx. bowing 1.1 SUMMARY A. Section includes: 1. Precst, prestressed, insulted structurl concrete pnels. FLATNESS The degree to which surfce pproximtes plne. HARPED (DEFLECTED) STRAND The pth of prestressing strnd in member my be ltered from the horizontl to increse lod crrying cpcity or to control member stresses, or both. This prctice is referred to s hrping, deflecting or depressing the strnd. SMOOTHNESS Due to Fbcon s unique mnufcturing process norml PCI smoothness tolernces do not pply. Consult your Fbcon engineer for finish specific tolernces. length of bow Exposed fce (convex) Exposed fce (concve) Mx. bowing Bowing (cross section) Bowing (elevtion) Length of bow (elevtion) B. Relted work specified elsewhere: Section Cst-in-plce concrete. Section Structurl steel frming. Section Metl fbrictions. Section Sheet metl flshing nd trim. Section Joint selnts: Perimeter joints with selnt nd bcking. Section Pinting nd coting: Preprtion of concrete surfces beyond specified level of concrete finish required prior to pinting. C. Work furnished nd instlled by others: SWEEP A vrition in horizontl lignment from stright line prllel to centerline of member (horizontl bowing). TOLERANCE Permissible vrition from specified requirements. BOWING An overll out-of-plne curvture of surfce whose edges remin prllel. WARPING The twisting of member resulting in n overll out-of-plne curvture of surfces, chrcterized by non-prllel edges. Precst concrete pnel Length of bow (cross section) PANEL BOWED in BOTH ELEVATION nd CROSS SECTION True plne 1. Receivers or Reglets for flshing. 2. Elevtor guides. 3. Steel required for br joist bering unless otherwise noted. 4. Deck ngle, if required. 5. All loose steel nd connections for bems where they ttch to precst unless otherwise noted. 6. Hollow core plnk, support steel, ll connection steel, culk nd connections between precst wll pnels nd hollow core plnk unless otherwise noted. Distnce to frthest djcent corner Distnce to nerest djcent corner 7. Any steel frmes t openings. Not required for structurl resons. If needed for esthetics, to be furnished nd instlled by others. 8. Culk between precst wll pnels nd djcent mterils. FABCONPRECAST.COM 5 6 FABCONPRECAST.COM

5 1.2 REFERENCES A. The publictions listed below form prt of this specifiction to the extent referenced. Applicble sections of these publictions re referenced within the text. B. AWS Americn Welding Society ASTM ASTM Interntionl PCI Precst/Prestressed Concrete Institute. ACI Americn Concrete Institute A. Submittl procedures: 1.3 SUBMITTALS Submit ll submittls electroniclly in PDF formt vi emil, unless other wise specified. B. Shop drwings: C. Product design criteri: 1. Plns, elevtions, nd detils indicting pnel loctions, design lods, construction (including welding requirements, finish, nd openings etc.), identify product provided by the mnufcturer. 2. Shop drwings shll be signed nd seled by professionl engineer licensed in the jurisdiction in which the project is locted. Design clcultions shll be performed by n engineer experienced in precst, prestressed concrete design. Design clcultions, signed by professionl engineer licensed in the jurisdiction in which the project is locted, shll be submitted upon request. Informtion shll include: 1. Ded, live, wind, nd seismic lods s identified in contrct documents nd s required by pplicble codes. 2. Temporry brcing lods if required D. Test reports: Test reports on concrete nd other mterils used in fbriction. Submittl is not required unless specificlly requested, reports to be mintined reports on file with the mnufcturer nd vilble upon request. A. Mnufcturer s qulifictions: 1.4 QUALITY ASSURANCE The mnufcturer s precst concrete production fcility shll be certified by PCI Plnt Certifiction Progrm. Mnufcturer shll hve produced product similr to wht is specified for minimum of two yers. B. Erector s qulifictions: C. Welders qulifictions: 1. Regulrly engged for minimum of five yers in the erection of precst structurl concrete similr to the requirements of this project. 2. Erection crews shll be certified by PCI Field Certifiction Progrm prior to strt of precst instlltion. 1. In ccordnce with AWS D1.1/1.1M nd D1.4/1.4M. 1.5 DELIVERY, STORAGE, AND HANDLING A. Trnsport, hndle, store, nd protect products in complince with mnufcturer s recommendtions. B. Support pnels during shipment on shock-bsorbing mteril. C. Store units with dequte brcing nd protect units to prevent contct with soil, to prevent stining, nd to prevent crcking, distortion, wrping or other physicl dmge. 1. Store units with dunnge cross full width of ech bering point unless otherwise indicted. 2. Plce dequte dunnge of even thickness between ech unit. 3. Plce stored units so identifiction mrks re clerly visible nd units cn be inspected. D. Hndle nd trnsport units in position consistent with their shpe nd design. E. Lift nd support units only t designted points shown on shop drwings nd/or per mnufcturer s recommendtions. FABCONPRECAST.COM 7 8 FABCONPRECAST.COM

6 PART 2 - PRODUCTS E. Steel reinforcing: 2.1 PRECAST CONCRETE WALL PANEL MANUFACTURER A. Fbcon: Svge, MN; Plesnton, KS; Grove City, OH; nd Mhnoy City, PA. 2.2 WALL PANELS A. Precst, prestressed insulted sndwich wll pnels nd/or VersCore+Green by Fbcon, s indicted on drwings. 2.3 DESIGN CRITERIA AND REGULATORY REQUIREMENTS A. Comply with the design recommendtions in PCI MNL 120. Comply with pplicble building codes. B. Clculted Fire-Test-Response chrcteristics: provide precst concrete units with fire-resistnce rting indicted s clculted ccording to PCI MNL 124 nd cceptble to uthorities hving jurisdiction. A. Portlnd Cement: ASTM C 150. B. Admixtures: 2.4 MATERIALS 1. Air-entrining dmixtures: ASTM C Wter reducing, retrding, ccelerting, high-rnge wter reducing dmixtures: ASTM C Fly sh s required by the mnufcturer. C. Aggregtes: ASTM C 33 or C 330. D. Wter: Potble nd free of foreign mterils in mounts hrmful to concrete, ggregte, or embedded steel. 1. Reinforcing brs: deformed billet steel: ASTM A 615, deformed ril steel ASTM A616, deformed xle steel ASTM A617, deformed low lloy steel ASTM A Wire: cold-drwn steel: ASTM A Wire fbric:. Welded steel: ASTM A 185. b. Welded deformed steel: ASTM A 497. F. Strnd: Uncoted, 7-wire, stress relieved or low relxtion steel strnd: ASTM A 416 (including supplement) Grde 250K or 270K. G. Anchors nd inserts: Structurl steel, ASTM A 36, mnufcturer s stndrd finish. H. Wythe connectors: Polypropylene. I. Rigid insultion: Expnded polystyrene bord insultion nd expnded polystyrene billets. J. Bering pds: High density plstic or hrdbord shims or combintion of both s recommended by precst concrete fbrictor. K. Snd-cement grout: 1. Portlnd Cement: ASTM C 150, Type I. 2. Clen, nturl snd: ASTM C 144 or ASTM C 404. L. Joint selnt: Sikflex 2c NS by Sik Corportion, (800) or (201) Color selection to be from mnufcturer s stndrd plette nd mtched to djcent precst concrete wll pnel color, unless selected/pproved by owner s representtive. 2.5 CONCRETE MIXES A. Mix design for the project, to provide concrete with the following properties: 1. Compressive strength: 7000 psi min. t 28 dys. 2. Relese strength: 3500 psi min. 3. Clcium chloride, chloride ions, nd/or other slts re not permitted. FABCONPRECAST.COM 9 10 FABCONPRECAST.COM

7 4. Entrined ir: 4 percent min. entrined ir concrete t exposed surfces. 9.5 percent +/- 1.5 percent on structurl portion of pnels. 2.6 GROUT MIXES A. Portlnd Cement nd snd with minimum wter required for plcement nd hydrtion. 2.7 FABRICATION A. Mnufcturing procedures shll be in generl complince with PCI MNL 116. E. Ptching: the structurl portion. Openings smller thn 12 inches re to be field cut by the trde requiring the opening fter the precst, prestressed products hve been erected. All openings shll be pproved by the rchitect/engineer nd the precst mnufcturer before drilling or cutting. 2. For insulted pnels, to minimize the risk of leks, full depth hed flshing is required t ll openings. Penetrting the hed flshing or filure to follow this detil my result in leks, which re not the responsibility of the mnufcturer. 1. Mintin structurl integrity. 2. Conform to pnel fbrictor s recommendtions nd directions. B. Mnufcturing tolernces shll generlly comply with PCI plnt certifiction for structurl products. C. Finishes: In generl, finishes will comply with Grde B per PCI MNL 116, 4th ddition, Appendix C D. Openings: 1. Stndrd underside: (Formed Finish).. Provide finish produced by csting ginst pproved forms using good industry prctice in clening forms, design of concrete mix, plcing nd curing. b. Smll surfce holes cused by ir bubbles, norml color vrition, norml form joints, minor chips nd splls shll be tolerted. No mjor or unsightly imperfections, honeycombs or other defects shll be permitted unless they re nonstructurl in nture nd re ptched per industry stndrds. 2. Stndrd top: (Exposed Unformed Surfce finish):. Extent of finishes s indicted on the drwings. b. Provide finish resulting from vibrtory screed nd dditionl hnd finishing. c. Norml color vrition, minor indenttions, minor chips nd splls shll be permitted. No mjor imperfections, honeycombs or defects shll be permitted unless they re nonstructurl in nture nd re ptched per industry stndrds. d. Colors: per design requirements 1. Openings my be plnt cst or swn (either in plnt or field). Plnt fbricte openings 12 inches round or squre nd lrger s indicted on the pproved shop drwings. Openings included t the time of mnufcture will hve minimum of 3 of solid concrete t the perimeter. In cses where the insultion extends to the opening, window/door frmes for insulted pnels must be of sufficient width to cover insultion nd llow nchorge into FABCONPRECAST.COM 11 F. Fsteners: Cst in structurl inserts, bolts, nd pltes s indicted on shop drwings. G. Insultion: Plce full length of pnel nd spce cross pnel width between reinforcing strnds. H. Identify pickup points of precst structurl concrete units nd orienttion in structure with permnent mrkings, complying with mrkings indicted on shop drwings. Imprint or permnently mrk csting dte on ech precst structurl concrete unit on surfce tht will not show in finished structure. I. Cure concrete ccording to requirements in PCI MNL 116 by moisture retention without het or by ccelerted het curing using low-pressure live stem or rdint het nd moisture. Cure units until compressive strength is high enough to ensure tht stripping does not hve n effect on performnce or ppernce of finl product. 2.8 SOURCE QUALITY CONTROL A. Qulity-control testing: In generl complince with testing provisions in PCI MNL 116, Mnul for Qulity Control for Plnts nd Production of Precst, Prestressed Concrete Products. Testing will be performed by mnufcturer s qulified personnel t the production fcility. PART 3 - EXECUTION 3.1 PREPARATION - Responsibilities of the Generl Contrctor (GC) nd/or Construction Mnger (CM) A. Provide suitble ccess to nd round building with proper dringe nd firm, level bering for huling nd erection equipment. Provide stble, compcted, nd drinble 40-foot wide ll-wether ggregte 12 FABCONPRECAST.COM

8 surfcing, cpble of ccommodting up to 90,000 pounds gross weight, to remin in plce throughout pnel erection. Coordinte with precst mnufcturer for loction. All equipment, including but not limited to crnes, trucks, forklifts nd mnlifts, must be cpble of moving under their own power in n unobstructed mnner so s not to cuse erection delys for the durtion of the erector s work on site. B. Provide true, level bering surfces on field plced bering wlls nd other field plced bering structures. Ensure tht ll foundtions re completed, properly cured nd redy to receive precst per the pproved erection sequence nd durtions. Mintin bering surfce in clen condition until precst is instlled. C. Excvting is recognized s one of the most hzrdous construction opertions. GC shll meet ll requirements set forth by OSHA in Subprt P, Excvtions, of 29 CFR , 29 CFR , nd 29 CFR This includes meeting the conditions prior to pnel being set s well s fter the pnel is set s this my cuse hzrds due to cve in ginst set pnel. D. Plce nd lign nchor bolts, pltes or dowels in column footings, grde bems nd other field plced bering structures. E. Estblish nd mintin control points nd benchmrks in n undisturbed condition for the use of the erector until finl completion nd cceptnce of the project. Control points shll consist of permnent pins inserted into the top of the footing by the Surveyor of Record t ll building corners t mximum of 75 intervls, long the footing foundtion nd t the tops nd bottoms of ll steps in the foundtion. Benchmrk finished floor elevtion mrkers re required to be permnently estblished within the building pd. F. Remove or de-energize ll power lines per OSHA guidelines, mrk underground utilities, secure permits, including those for irport ccess, e.g. FAA permit for crne clernce. drwings. Coordinte with the precst concrete pnel fbrictor to locte field cut openings to void unnecessry cutting of pnel reinforcement. Field cut openings shll be verified by the mnufcturer to mintin structurl integrity of the work. 3.3 ALIGNMENT A. Erect precst structurl concrete units level, plumb, squre, true, nd in lignment in generl complince with the erection tolernces of PCI MNL 135. Members shll be properly ligned nd leveled s required by the pproved shop drwings. B. Vritions between djcent slb members shll be resonbly leveled out by jcking, loding, or other industry stndrd method recommended by fbrictor. 3.4 FIELD QUALITY CONTROL A. Inspect ll instlled precst pnels for conformnce with pproved shop drwings nd industry stndrds. Field qulity control testing nd inspection shll be t the discretion nd expense of the GC or CM nd/or Owner s necessry to ssure complince with contrct requirements. B. Mnufcturer to cooperte with GC or CM nd/or Owner in ny discretionry testing nd inspection. 3.5 CLEANING AND PROTECTION 3.2 INSTALLATION A. Instlltion of precst, prestressed concrete shll be performed by the mnufcturer or mnufcturer s pproved erector under the PCI Certified Erector Progrm.. Members shll be lifted by mens of suitble lifting devices t points provided by the mnufcturer. A. Comply with mnufcturer s instructions nd recommendtions for clening precst concrete pnels when pnel erection is complete. B. Following instlltion, the GC nd/or CM shll be responsible for protecting the product from the elements to prevent dmge, discolortion nd/or moisture infiltrtion. b. Temporry shoring nd brcing, if necessry, s shown on the pproved shop drwings, shll comply with the mnufcturer s recommendtions. B. Sel joints between the precst pnels nd instll fire stopping mteril s shown, if required, on the pproved shop drwings in joints. Instll in complince with mnufcturer s instructions nd recommendtions. C. Field Welding: Perform field welding by qulified welders using equipment nd mterils in ccordnce with AWS D1.1/1.1M nd D1.4/1.4M. D. Round or squre openings less thn 12 inches in size shll be locted nd field drilled or cut by the trde requiring the opening fter the pnels hve been erected unless indicted otherwise on the pproved shop FABCONPRECAST.COM FABCONPRECAST.COM

9 THE REACH & RESOURCES OF FABCON THE FABCON ADVANTAGE A full engineering deprtment A wide selection of finishing options Outstnding therml performnce A controlled mnufcturing environment ensures consistency Multiple mnufcturing plnts provide speed nd cpcity Fbcon meets your need for green with considerble levels of post-consumer nd post-industril content. Precst mke-up my vry by loction. Ask your sles engineer for detils. SALES OFFICES MINNEAPOLIS, MN COLUMBUS, OH ALLENTOWN, PA KANSAS CITY, KS MANUFACTURING PLANTS CORPORATE & ALL PLANTS SAVAGE, MN GROVE CITY, OH MAHANOY CITY, PA PLEASANTON, KS QUENTIN AVE S SUITE 200 SAVAGE, MN FbconPrecst.com