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MECHANICAL SERVICES
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Technology in ArchitectureLecture 9 Vertical TransportationElevators Design ConsiderationsElevator Selection ParametersExample Problem
Vertical Transportation
ClassificationElevatorsPassengerFreightSpecial service
Escalators
TypesElevatorstractiongearless medium-high speed passengergeared low speed passengerhydraulicplungerhole-lessroped
Performance CriteriaIdeal Performance:minimum waiting timecomfortable accelerationrapid transportationsmooth/rapid slowingaccurate levelingrapid loading/unloadingquick/quiet door operationgood visual travel direction/floor indicatorseasily operated controlscomfortable lightingreliable emergency equipmentsmooth/safe operation of mechanical equipment
Codes and StandardsANSI/ASME Code A17.1
NFPA 101 Life Safety CodeNFPA 70 ElectricalANSI A117.1 Barrier Free
Elevator Design Considerations
Passenger Elevator ComponentsTraction Elevatorcarcableselevator machinecontrolscounterweighthoistwayrailspenthousepit
S: p. 1395, F.31.1
Traction Elevator ComponentsMachine room8-6 minimum clear
Bottom of Beam (OH)17-6 206
Travelnumber of floors
Pit (P)10-1 11-5S: p. 1439, F.31.29
Passenger Elevator ComponentsHydrauliccarplunger/piston/jackelevator machinecontrolshoistwayrailspenthouse/headwaypit
S: p. 1400, F.31.5
Hydraulic Elevator ComponentsMachine room7-9 minimum clear
Bottom of Beam (OH)12-0 123
Pit (P)/Plunger4-0Travel +2-6S: p. 1402, F.31.6
Design ConsiderationsDoorssingle slide (24-36)center opening (42-60)two-speed, side opening (42)two-speed, center opening (60)S: p. 1406, F.31.12
Elevator Selection Parameters
DefinitionsInterval (I) or lobby dispatch timeaverage time between departure of cars from lobby
Waiting timeaverage time spent by a passenger between arriving in the lobby and leaving the lobby in a carequals (0.6 x I)S: p. 1421, T.31.4
DefinitionsCar passenger capacity (p)passengers per car
S: p. 1422, T.31.5
DefinitionsHandling Capacity (HC)maximum number of passengers handled in a 5 minute periodwhen expressed as a percentage of the building population it is called percent handling capacity (PHC)
HC= 300(p) IS: p. 1422, T.31.6
DefinitionsAverage trip time (AVTRP)average time from passengers from arriving in lobby to leaving car at upper floor
Note: car size floor to floor heightS: p. 1424, F.31.20
DefinitionsRound-trip time (RT)average time required for a car to make a round trip
S: p. 1425, F.31.21
ParametersBuilding populationtypical area per personbased on net area and building type
S: p. 1423, T.31.7
ParametersOffice building efficiencynet usable area as a percentage of gross area
S: p. 1423, T.31.8
ParametersElevator equipment recommendationsbuilding typecar capacityrisespeed
S: p. 1432, T.31.9
Sizing EquationsHandling capacity (HC): HC=300p/I
Interval (I): I=RT/N
5-min. handling capacity (h): h=300p/RT
Number of cars (N): N=HC/h
Elevator Design Example
Example ProblemDesign an elevator system for a 10 story, single purpose tenant, office building that provides an good level of service.
Construction level is normal
Floor height: 12-0 floor to floor
Floor area: 15,000 net square feet (nsf) each
1. Determine Percent Handling Capacity (PHC)Office building Investment
range 11.5-13 %say 12%PHC=0.12S: p. 1422, T.31.6
2. Determine Interval (I)Office building Good service
I=25-29 secS: p. 1421, T.31.4
3. Determine Building PopulationOffice building Single tenantNormal construction
range 90-110 sf/personsay 100 sf/person
Pop= 9 floors@15,000 nsf 100sf/personPop=1350 peopleS: p. 1423, T.31.7
4. Determine Handling Capacity (HC)PHC=0.12 HC=0.12 x 1350 people
HC= 162 people
5. Determine Rise & Select Car9 floors (above lobby)12-0 floor-floor
Rise=9 x 12-0Rise=108
Select Car:2500# car@400 fpmS: p. 1432, T.31.9
6. Determine Average Trip Time (AVTRP)12-0 floor-floor2500# car400 fpm9 floors
AVTRP= 64 secS: p. 1425, F.31.21
7. Determine Round Trip Time (RT)12-0 floor-floor2500# car9 floors 400 fpm
RT= 112 secS: p. 1428, F.31.23
8. Verify Single Car Capacity (p)2500# car
p= 13 peopleS: p. 1422, T.31.5
9. Determine 5-minute Handling Capacity (h)h=300p/RT
h= 300 x 13/112
h= 34.8 people
10. Determine number of cars (N)N=HC/h
N= 162/34.8
N= 4.7 cars say 5 cars
11. Confirm Interval (I)I=RT/N
I= 112/5
I= 22.4 sec
Required I 25-29 sec
Design exceeds performance requirements
12. Repeat Until Performance CompliesTry 4 cars (2500 lbs., 400 fpm)
11. (Re)Confirm Interval (I)I=RT/N
I= 112/4
I= 28 sec
Required I 25-29 sec
Design meets performance requirements
12. Repeat Until Performance CompliesPerformance is in compliance
Use 4 cars (2500 lbs., 400 fpm)
Elevator Lobby Requirements
Lobby ParametersProximity to other carssingle zonemultizoneProximity to emergency exits/egress stairsAdjacent to main lobby
S: p. 1438, F.31.27
Lobby SizingSize based on peak interval15 or 20 minute peak time5 sf/person
From previous example using 15 minute peak
h=34.8 people/5-min. 104.4 people/15 min.
Area= 104.4 people x 5 sf/person = 522 sf