Earthquake design in lift planning

Earth­quakes in Switzer­land? In fact, the earth­quake risk here should not be under­es­ti­mat­ed. Switzer­land lies close to the bound­ary between the Euro­pean and African plates. This plate bound­ary leads to ten­sions that are occa­sion­al­ly released in the form of earth­quakes.

The regions with the high­est earth­quake risk in Switzer­land are Valais, Basel, Graubün­den and the St. Gallen Rhine Val­ley. There are no regions in Switzer­land with no earth­quake risk at all. The Swiss Seis­mo­log­i­cal Ser­vice (SED) reg­is­ters an aver­age of three to four earth­quakes a day in Switzer­land and neigh­bour­ing coun­tries. Most of these are not felt by the pop­u­la­tion. How­ev­er, a dam­ag­ing quake can­not be ruled out.

At the same time, Switzer­land is grow­ing ever taller. In recent years, numer­ous high-rise build­ings with a height of 100 metres and more have been added. The trend towards urban den­si­fi­ca­tion and ver­ti­cal­i­sa­tion con­tin­ues unabat­ed. Lifts are an impor­tant ele­ment in the oper­a­tion of these build­ings. 

What is seismic design? 

Earth­quake design refers to the process of plan­ning and design­ing struc­tures to ensure their safe­ty and sta­bil­i­ty dur­ing an earth­quake. Struc­tures should be able to with­stand the forces and move­ments that occur dur­ing an earth­quake with­out cat­a­stroph­ic fail­ure. Earth­quake design is there­fore an essen­tial part of civ­il engi­neer­ing that can save lives and sig­nif­i­cant­ly reduce mate­r­i­al dam­age. 

Design of lift systems under earthquake conditions 

SIA 261 

Among oth­er things, SIA 261 describes the legal­ly bind­ing actions and mea­sures to be tak­en in the event of an earth­quake. In the con­text of build­ings, lifts count as sec­ondary com­po­nents and as “com­po­nents that could endan­ger peo­ple or dam­age the sup­port­ing struc­ture in the event of fail­ure”. Pre­cau­tions must there­fore also be tak­en for lifts in the event of an earth­quake. 

SIA 18/370 

In accor­dance with SIA 118/370 “Gen­er­al con­di­tions for lifts, esca­la­tors and mov­ing walks”, the client must spec­i­fy whether and with which val­ues the lift com­pa­ny car­ry­ing out the con­struc­tion must take into account. 

SN EN 81–77 

The exact mea­sures that apply to lifts are explained in the SN EN 81–77 stan­dard. This stan­dard reg­u­lates the safe­ty aspects of the design and instal­la­tion of lifts under earth­quake con­di­tions. The design accel­er­a­tion fac­tor plays a deci­sive role in the cor­rect design. Depend­ing on the lev­el of this val­ue, the con­struc­tion is divid­ed into dif­fer­ent earth­quake cat­e­gories for lifts, which in turn entail dif­fer­ent mea­sures.  

A dis­tinc­tion is made between 4 cat­e­gories:

Rat­ed accel­er­a­tion m/s2	Earth­quake cat­e­go­ry for lifts	Remark
ad < 1	0	The require­ments of EN 81–20 and EN 81–50 are appro­pri­ate, there­fore no addi­tion­al mea­sures are required.
1 ≤ ad < 2,5	1	Minor cor­rec­tive mea­sures required
2,5 ≤ ad < 4	2	Medi­um cor­rec­tive mea­sures required
ad ≥ 4	3	Sig­nif­i­cant cor­rec­tive mea­sures required

The nec­es­sary mea­sures result­ing from the cat­e­gories include (but are not lim­it­ed to) 

Require­ments accord­ing to EN 81–77	Earth­quake cat­e­go­ry for lifts 1	Earth­quake cat­e­go­ry for lifts 2	Earth­quake cat­e­go­ry for lifts 3
Pre­ven­tion of catch­ing points	x	x	x
Emer­gency guide for the car		x	x
Car inter­locks		x	x
Emer­gency guides for the coun­ter­weight or bal­anc­ing weight	x	x	x
Pro­tec­tion of trac­tion sheaves, rope pul­leys or chain wheels	x	x	x
Guide rail sys­tem	x	x	x
Engine and con­trol unit	x	x	x
Addi­tion­al elec­tri­cal instal­la­tions in the shaft	x	x	x
Behav­iour in the event of fail­ure of the nor­mal pow­er sup­ply		x	x
Earth­quake detec­tion sys­tem			x

Earthquake design: early involvement of lift experts pays off

The require­ments and mea­sures described can have a major impact on costs and shaft dimen­sions. It is there­fore worth strength­en­ing the plan­ning team with exper­tise in lift plan­ning in the ear­ly plan­ning phas­es. 

As cer­ti­fied lift experts, we sup­port build­ing own­ers and archi­tects right from the com­pe­ti­tion phase, spec­i­fy the lift sys­tems, put them out to ten­der on a man­u­fac­tur­er-neu­tral basis and accom­pa­ny their imple­men­ta­tion right through to accep­tance. We are also hap­py to advise you on sys­tem refur­bish­ment.

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