Subchapter 6. Elevator Safety Orders
Article 18. Design Data, Formulas, Tests on Approved Devices, and Electrical Regulations

§3101. Electric Elevator Car Frame and Platform Stresses and Deflections.

(a) General Requirements.

(1) Steel, where used in the construction of car frames and platforms, shall conform to the following requirements:

(A) Steel shall be rolled, formed, forged, or cast, conforming to the requirements of the following specifications of the American Society for Testing and Materials:

1. Rolled and Formed Steel, ASTM A36 or ASTM A283 Grade D

2. Forged Steel, ASTM 235 Class C.

3. Cast Steel, ANSI G50.1 ASTM A27 Grade 60/30.

(B) Steel used for rivets, bolts, and rods shall conform to the following specifications of the American Society for Testing and Materials.

1. Rivets, ASTM A502.

2. Bolts and Rods, ASTM A307.

Exception: Steels of greater strength than those specified may be used provided they have an elongation of not less than 22 percent in a length of 2 inches, and provided that the stresses and deflections conform to the requirements of Design Sections 3101(a)(4) and (a)(5).

(2) Wood used for platform stringers and for platform floors and subfloors shall conform to the requirements of ANSI 04.3 -(ASTM D245-687).

(3) Paint used for protection against fire shall be of an approved type having a flame spread rating of not over 50, applied in accordance with the instructions of the manufacturer. Such ratings shall be based on the test procedures specified in ANSI A2.5.

(4) The stresses in car frame members and their connections, based on the static loads imposed upon them, shall not exceed the following:

(A) For steels meeting the requirements of Sections 3101(a)(1)(A) and 3101(a)(1)(B), the stresses listed in Table 3101 A4.

(B) For steels of greater strength, the stresses listed in Table 3101 A4 may be increased proportionately based on the ratio of the ultimate strengths.

(C) For metals other than steel, the factor of safety shall be not less than is required for steel.

TABLE 3101 A4 Maximum Allowable Stresses in Car Frame and Platform Members

and Connections, for Steels Specified in Sections 3101(a)(1)(A) and

3101(a)(1)(B)

 
_______________________________________________________________________________
                                                   Max stress                  
Member .......................... Type of stress . psi ......... Area basis    
_______________________________________________________________________________
Car Crosshead ................... Bending ........ 12,500 ...... Gross Section 
Car Frame Plank Normal .......... Bending ........ 12,500 ...... Gross Section 
 Loading                                                                       
Car Frame Plank Buffer .......... Bending ........ 25,000 ...... Gross Section 
 Reaction                                                                      
Car Frame Uprights (Stiles) ..... Bending plus ... 15,000 ...... Gross Section 
                                  Tension ........ 18,000 ...... Net Section   
Hoisting Rope ................... Bending plus                                 
 Hitch Shapes ................... Tension ........ 8,000 ....... Net Section   
Platform Framing ................ Bending ........ 12,500 ...... Gross Section 
Platform Stringers .............. Bending ........ 15,000 ...... Gross Section 
Threaded Brace Rods and ......... Tension ........ 8,000 ....... Net Section   
 other Tension Members                                                         
 Except Bolts                                                                  
Bolts ........................... Tension ........ 7,000 ....... Net Section   
Bolts in Clearance Holes ........ Shear .......... 7,000 ....... Actual Area in
                                                                 Shear Plane   
Bolts in Clearance Holes ........ Bearing ........ 16,000 ...... Gross Section 
Rivets or Tight Body-fit Bolts .. Shear .......... 10,000 ...... Actual Area in
                                                                 Shear Plane   
Rivets or Tight Body-fit Bolts .. Bearing ........ 18,000 ...... Gross Section 
Any Framing Member, Normal ...... Compression .... 14,000 ...... Gross Section 
 Loading ......................................... 59L/R                       
_______________________________________________________________________________
 
 

(5) The deflections of car frame and platform members, based on the static loads imposed upon them, shall be not more than the following, irrespective of the type of steel or other metal used:

(A) For crosshead, 1/960th of the span.

(B) For plank, 1/960th of the span.

(C) For stiles or uprights, as determined by Section 3101(e)(3).

(D) For platform frame members, 1/960th of the span.

(6) The stresses and deflections in side-post-type car frame and platform members shall be based on the data and formulas listed in this section.

(7) For cars with corner-post or underslung-type car frames, the formulas and specified methods of calculation do not generally apply and shall be modified to suit the specific conditions and requirements in each case.

(b) Car Frame Crosshead. The stresses in the car frame crosshead shall be based on the total load supported by the crosshead with the car and its rated load at rest at the top terminal landing.

(1) Where a hoisting rope sheave is mounted on the car frame, the construction shall conform to the following:

(A) Where multiple sheaves mounted on separate sheave shafts are used, provision shall be made to take the compressive forces, developed by tension in the hoist ropes between the sheaves, on a strut or struts between the sheave shaft supports, or by providing additional compressive strength in the car frame or car frame members supporting the sheave shafts.

(B) Where the sheave shaft extends through the web of a car frame member, the reduction in area of the member shall not reduce the strength of the member below that required. Where necessary, reinforcing plates shall be welded or riveted to the member to provide the required strength. The bearing pressure shall in no case be more than that permitted in Table 3101 A4 for bolts in clearance holes.

(C) Where the sheave is attached to the car crosshead by means of a single threaded rod or specially designed member or members in tension, the following requirements shall be conformed to:

1. The single rod, member or members, in tension shall have a factor of safety 50 percent higher than the factor of safety required for the suspension wire ropes, but in no case less than 15.

2. The means for fastening the single threaded rod, member or members, in tension to the car frame shall conform to Section 3033(m).

(c) Car Frame Plank (Normal). The stresses in the car frame plank shall be based on a uniformly distributed load equal to not less than the sum of 5/8 of the rated load, 5/8 of the platform weight, and the concentrated loads due to the tensions in the compensating ropes and traveling cables.

(d) Car Frame Plank (Buffer Engagement). In calculating the stress resulting from oil-buffer engagement, 1/2 the sum of the weight of the car and its rated load shall be considered as being concentrated at each end of the plank with the buffer force applied at the middle. The buffer force shall be considered to be that required to produce gravity retardation with rated load in the car.

The following formula shall be used to determine the stress resulting from buffer engagement:

Stress = (D[C + W]) /2Z
Where more than one oil buffer is used, the formula shall be modified to suit the location of the buffers.

Note: Symbols used in the above and subsequent formulas are defined in Section 3101(g).

(e) Car Frame Stiles (Uprights). The total stress in each car frame upright due to tension and bending, and the slenderness ratio of each upright and its moment of inertia, shall be determined in accordance with the following formulas:

(1) Stress Due to Bending and Tension.

Total Stress = (KL/4HZ _u) + (G/2A)

Where KL/4HZ _u is the bending stress in each upright in the plane of the frame due to the live load W on the platform for the class of loading A, B, or C for which the elevator is to be used, and G/2A is the tensile stress in each upright.

K is determined by the following formulas (See Figure 3101 E):

(A) For class A freight loading or passenger loading, K = WE/8

(B) For class B freight loading, K = W([E/2] - 48) or K = WE/8, whichever is greater

(C) For class C freight loading, K = WE/4

Note: Symbols used in the above formulas are defined in Section 3101(h).

Turning Moment Based on Class of Loading
FIGURE 3101E

(2) Slenderness Ratio. The slenderness ratio L/R for uprights subject to compressions other than those resulting from safety and buffer action shall not exceed 120.

Exception: Where the upper side-brace connections on passenger elevator car frame uprights are located at a point less than 2/3 of L from the bottom (top fastening in car frame plank), a slenderness ratio of L/R not exceeding 160 shall be permissible.

Note: Symbols used in the above formulas are defined in Section 3101(h).

(3) Moment of Inertia. The moment of inertia of each upright shall be not less than determined by the following formula:

I = KL ³ /18EH

Note: Symbols used in the above formula are defined in Section 3101(h).

(f) Freight Elevator Platforms.

(1) The calculations for the stresses in the platform members of freight elevators shall be based on the following concentrated loads assumed to occupy the position which will produce the maximum stress:

(A) Class A Loading: 1/4 of the rated load.

(B) Class B Loading: 75 percent of the rated load divided into two equal loads 5 feet apart.

(C) Class C1 and C2 Loading with a Full Load Rating of 20,000 pounds or less: 80 percent of the rated load or of the loaded truck, whichever is greater, divided into equal loads 2 feet 6 inches apart.

(D) Class C1 and C2 Loading with a Full Load Rating in excess of 20,000 pounds: 80 percent of 20,000 pounds or of the loaded truck weight whichever is the greater, divided into two equal parts 2 feet 6 inches apart.

(E) Class C3 Loading: Determine on the basis of the actual loading conditions but not less than that required for Class A loading.

(2) Freight elevators shall be designed for one of the following classes of loading:

(A) Class A -General Freight Loading. Where the load is distributed, the weight of any single piece of freight or of any single hand truck and its load is not more than 1/4 of the rated load of the elevator, and the load is handled on and off the car platform manually or by means of hand trucks.

For this class of loading, the rated load shall be based on not less than 50 pounds per square foot of inside net platform area.

(B) Class B -Motor Vehicle Loading. Where the elevator is used solely to carry automobile trucks or passenger automobiles up to the rated capacity of the elevator.

For this class of loading, the rated load shall be based on not less than 30 pounds per square foot of inside net platform area.

(C) Class C -These loadings apply where the weight of the concentrated load, including an industrial power or hand truck, if used, is more than 1/4 of the rated load and where the load to be carried does not exceed the rated load.

There are three types of Class C loading as follows:

Class C1 -Industrial Truck Loading where truck is carried by the elevator.

Class C2 -Industrial Truck Loading where truck is not carried by the elevator but used only for loading and unloading.

Class C3 -Other loading with Heavy Concentrations where truck is not used.

The following requirements shall apply to all three types of Class C loading:

1. The rated load of the elevator shall be not less than the load (including any truck) to be carried, and shall in no case be less than load based on 50 pounds per square foot of inside net platform area.

2. The elevator shall be provided with a two-way automatic leveling device.

For Class C1 and Class C2 loadings, the following additional requirements shall apply:

3. For elevators with rated loads of 20,000 pounds or less, the car platform shall be designed for a loaded truck of weight equal to the rated load or for the actual weight of the loaded truck to be used, whichever is greater. For elevators with rated loads exceeding 20,000 pounds, the car platform shall be designed for a loaded truck weighing 20,000 pounds, or for the actual weight of the loaded truck to be used, whichever is greater.

4. For Class C2 loading, the maximum load on the car platform during loading or unloading shall not exceed 150 percent of rated load. For any load in excess of the rated load, the driving machine motor, brake, and traction relation shall be adequate to sustain and level the full 150 percent of rated load.

Note: When the entire rated load is loaded or unloaded by an industrial truck in increments, the load imposed on the car platform while the last increment is being loaded or the first increment unloaded will exceed the rated load by part of the weight of the empty industrial truck.

(g) Passenger Elevator Platforms. The stresses in platform members of passenger elevators shall be based on concentrated loads not less than those which apply to Class A freight loading.

(h) Formula Symbols. The symbols used in the formulas in Section 3101 shall have the following meanings:

W = Rated load in pounds.

C = Net weight in pounds of complete elevator car.

G = Load in pounds supported by crosshead with rated load in car at rest at top terminal landing.

K = Turning moment in inch-pounds as determined by class of loading.

D = Distance in inches between guide rails.

E = Inside clear width of car in inches, except in formulas in Sections 3101(e)(3) and 3103(a)(4)(D) where E = modules of elasticity (psi) of the material used.

H = Vertical center distance between upper and lower guide shoes (or rollers) in inches.

L = Free length of uprights in inches (distance from lowest fastening in crosshead to top fastening in plank).

A = Net area of section in (inches) ².

R = Least radius of gyration of section in inches.

I = Moment of inertia of member, gross section in (inches) ⁴.

Z = Combined section moduli of plank members, gross section, (inches) ³.

Z _u =Section modulus of one upright, gross section, (inches) ³.

<General Materials (GM) - References, Annotations, or Tables>
 HISTORY     1. Amendment of subsections (a)(1), (a)(2), (a)(3) and (e) filed 6-23-77;
effective thirtieth day thereafter (Register 77, No. 26).

2. Editorial correction of subsections (d) Note and (f)(2)(C)3. (Register 95, 
No. 34).

3. Change without regulatory effect amending subsection (e) to provide more
legible illustrations in Figure 3101E filed 5-1-2009 pursuant to 
section100, title 1, California Code of Regulations (Register 2009, No. 18).