L9: Elevator Systems

Question 1

What happened to top floors when elevators were introduced?

Answer 1

Went from least valuable space to most valuable

Question 2

How much of a building’s initial cost is the elevators?

Answer 2

10%

Question 3

How much of a building’s energy use is elevators?

Answer 3

10%

Question 4

Where are elevators commonly located and why?

Answer 4

In the core;
Least valuable space
Utilitarian space that all tenants can access
Core reinforced shear wall which provides bracing

Question 5

What is the alternative to elevators being located in the core?

Answer 5

Along East/West sides;

Blocks harsh sun (glare/heat gain) but not suitable for multi-tenanted buildings

Question 6

How do sky lobbies work?

Answer 6

Express elevators takes occupants to sky lobbies covering a range of floors where another set of elevators continues to exact destination

Question 7

What are the two main purposes of sky lobbies?

Answer 7

Reducing wait time

Increasing leasable area (otherwise lower floors would just be elevator shafts)

Question 8

What is the elevator equipment?

Answer 8

Machine room (machine, controller, hoist ropes)
Moving components (car, counterweight, hoist ropes_
Stationary components (guide rails (car and counterweight), hydraulic car buffer, elevator shaft)

Question 9

How heavy is the counterweight in an elevator system?

Answer 9

The weight of the car plus half the maximum load

Question 10

What are hoist ropes and how are they used in elevator systems?

Answer 10

High tension steel cables with resin core

Used in sets of 4-8 per car to provide traction

Question 11

What is a hydraulic car buffer?

Answer 11

Located at bottom of elevator shaft and slows car if breaks fail

Question 12

What are the types of roping and sheave arrangement that can be used with a penthouse machine room?

Answer 12

1: 1 roping single wrap
1: 1 roping double wrap
2: 1 roping double wrap

Question 13

What is 1:1 roping single wrap?

Answer 13

Rope connected to car and counterweight goes over traction and secondary sheaves

Question 14

What is 1:1 roping double wrap?

Answer 14

Rope connected to car and counterweight goes over traction and secondary sheaves twice

Question 15

What is 2:1 roping double wrap?

Answer 15

Rope comes from machine room, attaches to car and countweight with a pulley, and wraps around traction and secondary sheaves twice; lower power/cost but slower

Question 16

What is the roping and sheave arrangement used with a basement machine room?

Answer 16

1:1 roping

Question 17

What is 1:1 roping?

Answer 17

Rope connected to car, goes over idler sheave above, goes down to traction sheave in basement, goes back up to another idler sheave above, connects to counterweight; requires longer ropes

Question 18

What are hydraulic elevators?

Answer 18

Hydraulic oil and pump drives pistons which lifts car; less expensive but very sloe and only for up to 6 storeys

Question 19

What are the 4 types of elevator operations control?

Answer 19

Single automatic push button
Selective collective operation
Computerised system control
Destination control system

Question 20

How do single automatic push-button elevators work?

Answer 20

Handles one call at a time; single button indicates if elevator is in use

Question 21

How do selective collective operation elevators work?

Answer 21

Most standard; system stores calls until answered and elevator completes up/down runs stopping where necessary (most appropriate car sent )

Question 22

How can wait times be improved with selective collective operation elevators?

Answer 22

Operating modes which send elevators to lobby at up peak times and to top floor at down peak times

Question 23

How do computerised system control elevators work?

Answer 23

Using specialised software and algorithms designed to minimise waiting and trip time by considering factors like car load and distance and assigning priority status to expired calls (uses AI)

Question 24

How do destination control system elevators work?

Answer 24

Floor is entered in control panels which indicate which elevator to take; avoids large random groups by grouping destinations efficiently

Question 25

What is the three main criteria for elevator system selection?

Answer 25

Interval and average wait time
Handling capacity
Travel time

Question 26

What is the internal and average wait time?

Answer 26

Interval: average time between departure of cars from lobby

Average wait time: interval x 60%

Question 27

What is the handling capacity?

Answer 27

The maximum number of passengers handled in given time (5m) determined by car sizes and interval

Question 28

What is travel time and what is the target/limit?

Answer 28

Lobby wait time + travel time to median floor stop

Target - less than one minute
Limit: two minutes