NORTH CAMPUS EXPANSION HOUSTON METHODIST HOUSTON, TEXAS FAÇADE ACCESS DESIGN DEVELOPMENT NARRATIVE DECEMBER 18, 2014 Prepared For: Chris Cook, AIA, LEED, AP Principal WHR Architects, Inc. 1111 Louisiana 26 th Floor Houston, Texas 77002 Prepared By: John Fatseas, P.E. Consultant ALL DOCUMENTS FURNISHED BY LERCH BATES INC. (LERCH BATES) ARE INSTRUMENTS OF SERVICE AND SHALL REMAIN THE SOLE PROPERTY OF LERCH BATES. LERCH BATES SHALL RETAIN ALL COMMON LAW, STATUTORY, AND OTHER RESERVED RIGHTS, INCLUDING THE COPYRIGHT THERETO. THEY ARE TO BE USED ONLY FOR THIS PROJECT AND ARE NOT TO BE MODIFIED, DISTRIBUTED, OR USED FOR ANY OTHER PROJECT, IN WHOLE OR IN PART, EXCEPT WITH THE WRITTEN AUTHORIZATION OF LERCH BATES. LERCH BATES ACCEPTS NO LIABILITY FOR ANY UNAUTHORIZED USE OR MODIFICATION OF THESE DOCUMENTS. 8089 S. Lincoln Street Suite 105 Littleton, Colorado 80122 T 3037957956 F 3037977109 www.lerchbates.com
TABLE OF CONTENTS SECTION I DESIGN DEVELOPMENT REVIEW... 1 A. GENERAL... 1 B. DATA... 1 C. FAÇADE ACCESS CHALLENGES... 1 D. CRITERA... 1 E. DISCUSSION... 1 SECTION II EQUIPMENT DESIGN... 3 A. EXTERIOR ACCESS... 3 B. RECOMMENDATIONS... 4 APPENDIX A INFORMATION ON TYPICAL DAVIT SYSTEMS... 5 APPENDIX B INFORMATION ON TYPICAL MONORAIL SYSTEMS... 8 APPENDIX C INFORMATION ON TYPICAL HORIZONTAL LIFELINES... 11 APPENDIX D INFORMATION ON TYPICAL SELFPOWERED WORK PLATFORMS... 13 APPENDIX E INFORMATION ON TYPICAL INTERMITTENT STABILIZATION ANCHORS... 15 APPENDIX F DEFINITION OF TERMS... 17 8089 S. Lincoln Street Suite 105 Littleton, Colorado 80122 T 3037957956 F 3037977109 www.lerchbates.com
SECTION I DESIGN DEVELOPMENT REVIEW A. GENERAL B. DATA 1. The purpose of this report is to present the initial design development recommendations by Lerch Bates Inc. (LB) Façade Access Consulting Group for façade access of Houston Methodist North Campus Expansion project to be located in Houston, Texas. Our objective for the systems outlined in this report is to provide total access to the exterior façades of the building. 2. The recommendations within this report will provide a high level of building maintenance for a reasonable cost while simultaneously limiting the impact of the façade access equipment on the buildings aesthetics and tenant use. 3. All equipment will be in strict accordance with OSHA 1910.66 and ASME A120.1 regulations. 1. Location: Houston, Texas 2. Project Type: Health Care 3. Building Information: Number of roof levels = 3 Approximate max drop height = 320 Approximate major dimensions = 230 x 480 C. FAÇADE ACCESS CHALLENGES 1. Platform roofrigging required 2. Occupyable roof space 3. Community rooftop pool 4. Multiple setbacks and roof levels D. CRITERA 1. We suggest the façade access equipment system should be capable of performance meeting the following criteria: E. DISCUSSION Exterior Façade Maintenance Cycle Time (FMCT): 4x per year Façade Maintenance Work Platform Live Load Capacity: 750 lb (minimum) 1. The information used for this report was provided by the WHR Design Team in December 2014. 2. For the purpose of this report we assume the façade maintenance will be performed four (4) times per year. 3. This report presents the following schemes for exterior access: a. Portable Davit System: Window cleaning and unscheduled maintenance on the majority of the building will be achieved with a standard portable davit system. The Page 1
davits will suspend a selfpowered work platform that will be roofrigged and descend to ground level. Platform stabilization will be required due to platform descents being greater than 130. Stabilization will be achieved using intermittent stabilization anchors (ISA). b. Monorail System: Window cleaning and unscheduled maintenance on the North popout (by the flag pole) will be achieved using a monorail system. The monorail system will consist of two manually powered trolleys that suspend a selfpowered platform and two turntables that allow the platform to traverse through 90 degree corners in the monorail track. Platform stabilization will be required due to platform descents being greater than 130. Stabilization will be achieved using intermittent stabilization anchors (ISA). c. Fall Protection: Parapets lower than 42 require fall protection within 6 feet of the roof edge. This will be achieved using a handsfree horizontal lifeline that workers can attach their harnesses. 4. The façade access system's intended use is building maintenance which includes window cleaning, caulking, and general light maintenance or repairs to building surfaces. Page 2
SECTION II EQUIPMENT DESIGN A. EXTERIOR ACCESS The exterior of the condominium building will be accessed by a portable davit system and monorail system for window cleaning and unscheduled maintenance. Both systems will suspend a selfpowered work platform and will utilize intermittent stabilization anchors (ISA) for platform stabilization. Refer to Appendices for details. 1. Davit arms cannot be transported between roof levels or buildings. Therefore, each roof level shall be equipped with two (2) portable davit arms and two (2) portable davit sockets. 2. The davit pedestal locations will be coordinated with structure, but shall not be spaced greater than 30 apart. 3. A modular selfpowered work platform will have a maximum length of 30'0" with removable modular sections allowing a minimum length of 10'0". The owner has the option of either purchasing or renting the work platform. A single platform can be shared between each roof level. 4. Platform stabilization is required for drops greater than 130 and will be achieved using intermittent stabilization anchors spaced vertically 50 (or every 3 floors whichever is less) and horizontally the same distance as the davit pedestal spacing. 5. The handsfree horizontal lifeline (HLL) will consist of stanchions spaced no greater than 30 0 apart connected by a stainless steel wire rope cable. The HLL will be designed for 2 workers to be continuously attached as they work near the edge of the roof. 6. This system does not have the load capacity to be used for façade panel replacement. Additional equipment including a counterweighted or tiedback Aframe would be required. This piece of equipment would be provided by the contractor, brought to roof level by the elevator, and assembled at the roof edge. 7. Safety and Operation: a. All portable equipment shall be tethered to prevent falling over the side of the building. b. All portable equipment shall have the ability to be disassembled into pieces that weigh no more than 50 lbs for transportation. c. All workers must use fall protection when approaching an unprotected roof edge. 8. Estimated Costs: 9. Pros: a. Davit system, monorail system, fall protection approximately $250,000 b. Work Platform approximately $100,000 a. Complies with state and national codes and standards b. Provides complete access to the exterior building façade for window cleaning and unscheduled maintenance Page 3
10. Cons: c. Efficient FMCT d. Long equipment life and minimal maintenance required e. Flexibility; additional equipment can be added easily to meet work load requirements f. Façade access equipment suspended from the rooftop keeps public walkways relatively open during use of equipment a. Location of equipment requires considerable coordination b. Storage areas for davit arms and sockets must be provided c. Does not include glass replacement activities B. RECOMMENDATIONS In making our recommendation we took into account three key factors: Compliance to current codes and standards, efficiency and ease of use, and health and safety of the worker. In order to meet these requirements, we recommend a standard portable davit system monorail system. We recommend the selfpowered work platform be purchased and stored in a designated, covered storage area. For a moderate firstcost investment, the Owner can obtain a façade access system that is a permanent part of the building s physical plant that will cover the entire building. Over the life of the building, this equipment will provide access to the exterior building envelope for a range of building maintenance activities. Additional design work is required to insure that the systems recommended in our report are fully integrated into the building design and operate per their original design criteria. Page 4
APPENDIX A INFORMATION ON TYPICAL DAVIT SYSTEMS Page 5
Image 1: Typical davit system being roof rigged Image 2: Typical davit arms in stored position Page 6
Image 3: Typical davit pedestal Page 7
APPENDIX B INFORMATION ON TYPICAL MONORAIL SYSTEMS Page 8
Image 4: Typical monorail recessed in soffit Image 5: Typical monorail recessed in soffit Page 9
Image 5: Typical monorail turntable Page 10
APPENDIX C INFORMATION ON TYPICAL HORIZONTAL LIFELINES Page 11
Image 6: Typical horizontal lifeline Image 7: Typical horizontal lifeline Page 12
APPENDIX D INFORMATION ON TYPICAL SELFPOWERED WORK PLATFORMS Page 13
Image 8: Typical rental work platform Image 9: Typical modular selfpowered work platform Page 14
APPENDIX E INFORMATION ON TYPICAL INTERMITTENT STABILIZATION ANCHORS Page 15
Image 10: Typical ISA [left empty, right engaged] Image 11: Typical ISA detent pin Page 16
APPENDIX F DEFINITION OF TERMS Page 17
Accessories Activation Distance Allowable Stresses American National Standards Institute Anchorage Angulated roping ANSI Arrest Distance Arresting Force Ascending Authorized Person Body Harness Brake, Primary Brake, Secondary Building Face Roller Those components which, when added to scaffolding or shoring, enhance their utility or usefulness. The distance traveled by a fall arrester or the amount of line payed out by a selfretracting lanyard (SRL) from the point of onset of a fall to the point where the fall arrester or selfretracting lifeline begins to apply a braking or stopping force. The working stress limitations imposed by a nationally recognized standardspromulgating organization. An organization which develops standard safety specifications and procedures for a wide range of industrial equipment including ladders and scaffold. Many OSHA regulations are based on these standards. Also known as ANSI. The terminating component of a fall protection system or rescue system that is intended to support any forces applied to the system. A method where a powered suspended work platform s point of suspension is inboard from the point of attachment on the suspended work platform, thus causing the suspended work platform to bear against the face of the building during its vertical travel. See American National Standards Institute. The total vertical distance required to arrest a fall. The arrest distance includes the deceleration distance and activation distance. The force, generated by arresting a load, that is transmitted through the fall arrest system components to the anchorage. A powered suspended work platform moving upward or climbing. A person approved or assigned by the employer to perform a specific type of duty or to be at a specific location on the jobsite. See Harness, Full Body A brake designed to be automatically applied whenever power to the prime mover is interrupted or discontinued. A brake acting directly on the drum, traction sheave, or final drive shaft, intended to stop the descent of the suspended or supported equipment or platform in the event of an overspeed condition A guide roller designed to ride on the face of the building wall to prevent the suspended or supported equipment from abrading the face of the building. Page 18
Building Maintenance Cable Reeler Caster Wheel Certified Certification Competent Person Configuration Connector Control Davit Dead Load (suspended work platform) Deceleration Device Deceleration Distance Dropline Dynamic Load Electrical ground Exterior or interior operations such as window cleaning, caulking, metal polishing, reglazing, and general light maintenance or repairs on building surfaces. Storage drum onto which electric cable is reeled. A swiveling wheel attached to the base of a powered suspended work platform for manual movement of the platform. Accepted by design, evaluation, or inspection by a registered professional engineer. A written, signed, and dated statement confirming the performance of a code or standard requirement. A designated person, suitably trained, qualified by knowledge and practical experience, and provided with the necessary instructions to enable the required task to be carried out safely. A person who is capable of identifying hazardous or dangerous conditions in powered suspended work platform and/or fall arrest installations and of training employees to identify such conditions. All shapes in which a scaffold can be placed within its intended limits. A component or element used to couple parts of the system together. A mechanism used to regulate or guide the operation of the façade access equipment. A device for suspending a powered work platform. Unlike outriggers, a davit reacts its operating moment load into a single pedestal, socket, carriage attachment, or other connection. The weight of the scaffold structure including platform and accessories. See Shock Absorber. The vertical distance between the user s fall arrest attachment at the onset of fall arrest forces during a fall, and after the fall arrest attachment comes to a complete stop. A vertical line from a fixed anchorage, independent of the work platform and its rigging, to which a lanyard is affixed. Droplines are also variously called lifelines, safety lines, ratlines, scarelines, etc. Loading induced by masses undergoing changes in velocity and loads varying with time. In application, a simulated static load surcharge may be assumed to be equivalent to dynamic effects. A conducting connection between an electrical device and the earth or another conducting body that serves in place of the earth. Page 19
Elevation End Guardrail Energy (Shock) Absorber Equivalent Façade Factor of Safety Failure Fair Lead Roller Fall Arrest Fall Arrest Device Fall Protection Fall Restraint Fixed Mast Free Fall Free Fall Distance Grade An established elevation in relation to sea level or another point. A guardrail placed across the end of a scaffold platform or its extensions. A component whose primary function is to dissipate energy and limit deceleration forces which the system imposes on the body during fall arrest. Alternative designs, materials, or methods which the employer can demonstrate will provide an equal or greater degree of safety for employees than the methods, materials, or designs specified in the standard. The face of a building, especially the front. The ratio of ultimate load to the allowable load. The condition at which a component or assembly can no longer support the load (load refusal). A roller provided to allow a minor change in the direction of travel of a suspension rope. The action or event of stopping a free fall or the instant where the downward free fall has been stopped. Device acting directly on a secondary wire rope, which automatically stops and holds the platform. Any equipment, device, or system that prevents an accidental fall from elevation or that mitigates the effect of such a fall. The technique of securing an authorized person to an anchorage using a lanyard short enough to prevent the person s center of gravity from reaching the fall hazard. A vertical steel column of fixed length that at its base is connected to the building maintenance unit turntable and at its top is connected to the roof machine boom arm. A fixed mast provides vertical height to clear obstructions so the suspended work platform can be deployed. The act of falling before a fall protection system begins to apply forces to arrest the fall. The vertical distance traveled during a fall, measured from the onset of a fall from a walking working surface to the point at which the fall protection system begins to arrest the fall. The ground, floor, sidewalk, roof, or any other approximately level solid surface of sufficient area and having sufficient structural strength to be considered a safe place to work. Page 20
Ground Rigging Ground Rigged Davit Guardrail System Guide Roller Harness, Full Body Hoist Machine Hoist Rated Load Horizontal Lifeline Installation Interlock Lanyard Lifeline Limit Switch Live Load (Static) A method of suspending a selfpowered work platform from a safe horizontal surface to an acceptable point of suspension above the safe surface. A davit which can only be used to suspend a selfpowered work platform from a safe horizontal surface to a point above the safe surface, but not from a roof above. A passive system of horizontal rails and vertical posts that prevent a person from reaching a fall edge. A rotating cylindrical member operating separately or as part of a guide assembly to provide continuous engagement between the suspended or supported equipment and the building guides or guideways. A body support designed to contain the torso and distribute the fall arrest forces over at least the upper thighs, pelvis, chest, and shoulders. A device intended to raise and lower a suspended work platform. The hoist manufacturer s maximum allowable operating load. A component of a horizontal lifeline subsystem, consisting of a flexible line with connectors or other coupling means at both ends for securing it horizontally between two anchorages or anchorage connectors. The total affected parts of a building and the equipment associated with the intended operation. A device designed to ensure that operations or motions occur in proper sequence. A flexible line used to secure a wearer of a harness to a dropline, lifeline, or fixed anchorage. See: Dropline A switch that automatically cuts off current to an electric motor when an object moved by it has passed a given point. The total static weight of personnel, tools, parts, and supplies that the equipment is designed to support. Load Allowable Dynamic The load limit at which the item is to be used; determined by dividing the ultimate load by an appropriate factor of safety. An additional load imposed on a scaffold structure caused by movement of the scaffold, wind movement of loads on the platform, brake engagement during movement, etc. Page 21
Heavy duty Light duty Maximum intended Medium duty Shock (shoring) Special duty Total (suspended) Ultimate load Working load A term applying to a scaffold designed and constructed to carry a working load of 75 pounds (34 kg) per square foot such as is intended for stone masonry work with storage material on the platform. A term applying to a scaffold designed and constructed to carry a working load of 25 pounds (11.3 kg) per square foot such as is intended for workers only with no material storage other than weight of tools. The total load of all persons, equipment, tools, materials, transmitted loads, and other loads reasonably anticipated to be applied to a scaffold or scaffold component at any one time. A term applying to a scaffold designed and constructed to carry a working load of 50 pounds (22 kg) per square foot such as is intended for bricklayers with weight of material in addition to workers. The impact of material such as fresh concrete as it is released or dumped on formwork during placement. A term applying to a scaffold designed and constructed to carry specific types of objects such as palletized materials; the design of planks and other types of scaffold units, the scaffold, and accessories shall be based on the categories of load ratings provided. The sum of all loads supported by the wire rope. The load at which failure occurs. See Load, Allowable. Midrail Mobile Davit NoPower Descent Obstruction Detector Occupational Safety and Health Act A horizontal member approximately midway between the toprail and platform of a guardrail system. A davit designed to be used in association with a roof car. Manually operated system which allows controlled descent of a power operated platform. A device that will stop the powered suspended work platform in the direction of travel if an obstruction is encountered and will allow the unit to move only in a direction away from the obstruction. A United States Federal Law that regulates safe work practices affecting employees; also known as OSHA. Opening A gap or void 30 inches (760 mm) or more high and 18 inches (480 mm) wide in a wall or partition through which a worker can fall to a lower level. Operator A designated person, suitably trained for working at height, qualified by knowledge and practical experience, and provided with the necessary instructions to enable operations to be carried out on SAE Page 22
OSHA Overload Detection Device Parapet Pedestal Personal Fall Arrest System Platform Modular Powered PlatformMounted Hoist Platform Rated Load Platform Stabilization Plumb Portable Davit Power Operated Hoist Primary Brake Prime Mover Registered Professional Engineer (P.E.) See Occupational Safety and Health Act. Device which trips and acts automatically to stop the upward motion of a platform if the load in the suspension wire rope(s) reach(es) the tripping limit. The part of a wall that extends above roof level which may or may not be structural. Steel or concrete supports for wideflange beam tracks or davit sockets that are attached to a building s structure. An assembly of components and subsystems used to arrest a person in a free fall from a working height. An elevated work surface composed of one or more units. Any platform assembled from standard components to form various lengths or configurations. A suspended work platform used to provide maintenance personnel access to the interior or exterior vertical faces of a building for the purpose of building maintenance which is raised and/or lowered by powered hoist equipment. Hoist which is mounted on the platform. The combined weight of workers, tools, equipment, and other material which is permitted to be carried by the working platform at the installation, as stated on the load rating plate. Means of stabilizing the platform to the façade (continuous or intermittent) to prevent the platform from being blown away from the façade by wind. In a perpendicular or vertical direction. A davit with a reach in excess of no more than 8'6" that, per code, is allowed to move from socket position to socket position. A hoist which is powered by other than human energy. See Brake, Primary. Source of power for the hoist, e.g. electric, hydraulic, pneumatic motors and hydraulic jack. A person who has been duly registered and licensed by an authority within the United States to practice the profession of engineering. Page 23
Qualified Person Rated Load (RL) Rated Speed Rated Working Load Restraint System Roller Bumper Roof Rigged Davit Roofing work Rope Safe Surface Safety Factor Safety Harness One who by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience has successfully demonstrated the ability to solve or resolve problems related to the subject matter, work, or project. The maximum mass which the suspended platform has been designed to carry as designed by the manufacturer. The rated load comprises persons and equipment. Average speed measured during the upward and downward hoisting travel of the platform with its rated load for a travel length of 10 m or more and with the rated power supply applied. The combined static weight of workers, materials, and suspended or supported equipment. System attaching the suspended platform to the mullions or other fixtures on the building and which limits the lateral movement of the suspended platform due to the wind. See Building face roller. A davit used to raise the suspended working platform above the face of the building being serviced; this type of davit can also be used to raise a suspended working platform which has been ground rigged. The hoisting, storage, application, and removal of roofing materials and equipment including related insulation, sheet metal, and vapor barrier work but not including the construction of the roof deck. The equipment used to suspend a component of an equipment installation (i.e. wire rope). A horizontal surface intended to be occupied by personnel, which is so protected that it can be reasonably assured that said occupants will be protected against injury or from falling. The ration of the nominal strength to the nominal load. A system of straps worn by a worker to arrest a fall when used as a part of a fall arrest system. Scaffold, Suspended Permanent Powered Scaffold Hoist Powered suspended equipment dedicated for building maintenance of a specific structure. A poweroperated scaffold suspended by wire rope from an overhead supporting system so arranged and operated as to permit raising and lowering to desired working positions. A device intended to raise and lower a suspended scaffold. Page 24
Screen Secondary Brake Secondary Device Secondary Rope SelfPowered Platform Service Brake Shackle Sheave Shock Absorber Sling Snaphook Soffit Span Stability Factor Stage Stirrup Strain Relief Anchor A wire or plastic mesh barrier installed between scaffold guardrails and toeboards to keep tools and materials from falling off the scaffolding platform; required whenever there are people working or passing under scaffolds. See Brake, Secondary. Device intended to stop the descent of the platform under emergency conditions, e.g. breaking of a suspension wire rope or failure of a hoist. Steel wire rope not normally carrying the suspended load, but rigged in conjunction with a fallarrest device. A powered work platform where the hoists are located on the platform. Mechanical brake, automatically applied by stored energy (e.g. spring force) until released with an external sustained power supply (electrically, hydraulically, pneumatically, etc.) under the control of the operator or automatically. A Ushaped structural steel attachment device. A pulley wheel inside a hoist or block and tackle which is used to gain traction or change the direction of the rope. A component of a system that allows dissipation of energy by extending the deceleration distance. A length of fiber or wire rope spliced together at the ends to form a circle; used to wrap around loads for the purpose of hoisting. A selfclosing device with a keeper, latch, or other similar arrangement that will remain closed until manually opened; this includes self closing, singleaction, doubleaction, and doublelocking snaphooks. The underside of a subordinate part or member of a building such as a beam, stairway, arch, eave, etc. The horizontal distance between posts, columns, or upright support members. A ratio of the stabilizing moment to the overturning moment. See Platform. The device that connects the hoist mechanism to the suspended platform. A mechanical device for anchorage of cable to prevent undue strain on the electrical cable connectors. Page 25
Suspended Equipment Suspension Rope Swaged Fitting Swing Stage Tag Line Tail line Tieback Tiein Device Tiein Guide Toeboard Toprail Total Load (suspended) Total Suspended Load Traction Hoist Tripping Limit Underwriters Laboratories, Inc. Weatherproof Winding Drum Hoist Building maintenance equipment that is suspended and raised or lowered to its working position by means of ropes or combination cables attached to some anchorage above the equipment. Active steel wire rope carrying the suspended load. A metal sleeve that is coldformed onto wire rope. See Scaffold, Suspended, Swing. A second rope attached to a load being hoisted or lowered to keep it from swinging out of control and striking workers, scaffold members, or other objects. The nonsupporting end of a suspension wire rope. An attachment from a structural member to a supporting device. Portion of a suspended unit that positively engages the building tiein guides. Portion of a building that provides continuous, positive engagement between the building and a suspended unit during its vertical travel on the face of the building. A barrier secured along the sides and the ends of a platform unit to guard against the falling of materials, tools, and other loose objects. The uppermost horizontal rail of a guardrail system. See Load, Total (suspended). Static force imposed on the suspension point(s), consisting of the rated load of the platform, the selfweight of the platform, the ancillary equipment, the wire ropes, and the electric cable, if any. An assembly through which the wire rope is conveyed as a result of friction between the wire rope and the traction assembly, with no tail load. The device does not accumulate the suspension robe but is designed to climb the rope by the application of a friction force between the rope and the drum or sheave. Static load which causes the overload detection device to operate. An organization that tests the safety aspect of a wide variety of equipment used in industry and in the home in accordance with a set of engineering and design standards. Equipment so constructed or protected that exposure to the weather will not interfere with its operation. A type of hoisting machine that accumulates the suspension wire rope on the hoisting drum. Page 26
Wire Rope Winder Work Cage Working Load Working Load Limit (WLL) Work Platform Wrap Storage drum onto which wire rope is reeled. A selfpowered suspended work platform that is suspended from a single suspension point. See Load, Working. Maximum load which a piece of equipment is authorized to sustain as designed by the manufacturer. The WLL is specified by the manufacturer. Suspended or supported equipment intended to provide access to the face of a building and manned by workers engaged in building maintenance. One complete turn of the suspension wire rope around the surface of a hoist drum. Page 27