Insufficient reserved dimensions for the elevator shaft or verticality deviation exceeding the limit, resulting in difficult elevator installation and excessive operational vibration.
Elevator shaft design involves close coordination among multiple disciplines: structural, architectural, mechanical, and electrical. Insufficient reserved dimensions, excessive verticality deviation, and incorrect ring beam positions are common shaft design problems that may render the elevator uninstallable or cause abnormal operation. Based on GB 7588-2003 Safety Code for the Construction and Installation of Electric Lifts and GB 55037-2022 General Code for Building Fire Protection, this article systematically analyzes the technical key points of shaft design.
Article 5.2 of GB 7588-2003 specifies in detail the shaft structure: the shaft walls shall have sufficient mechanical strength to withstand the loads generated by elevator operation, and a load-bearing beam shall be provided beneath the shaft roof slab with a load capacity not less than the load applied when the elevator is fully loaded. GB 50009-2012 stipulates that the live load of the elevator machine room shall not be less than 7.0 kN/m². GB 55037-2022 requires that the elevator shaft be provided independently, with the fire resistance rating of the shaft walls not less than 2.00 h and that of the landing doors not less than 1.00 h.
The clear shaft dimensions of a standard passenger elevator are 2200 mm wide × 2200 mm deep with center-opening doors, and those of a standard residential elevator are 2000 mm wide × 2000 mm deep. The shaft for a hospital elevator requires 2700 mm wide × 2800 mm deep. An installation clearance of 50 to 100 mm shall be reserved in all directions of the shaft. For super high-rise buildings, the influence of wind pressure inside the shaft on elevator operation shall also be considered, and shaft pressure regulation devices are usually required.
Reinforced concrete shaft walls are commonly used with a thickness of not less than 150 mm. The verticality deviation of the shaft over its full height shall not exceed 50 mm. Shaft ring beams are provided at intervals of 2.0 to 2.5 m to fix the guide rail brackets, with a cross-section of not less than 200 mm × 200 mm. The load-bearing beams are arranged at the top of the shaft to bear the entire load of the traction machine and the car, with a safety factor of not less than 3. The pit depth is 1.4 to 1.8 m, and the pit floor shall withstand a load of not less than 5000 N/m².
Regarding shaft fire protection design, it is strictly prohibited for the fire elevator shaft to be shared with other elevator shafts. A partition wall with a fire resistance rating of not less than 2.00 h shall be provided between adjacent shafts. Landing doors shall meet the EI60 fire resistance rating and be capable of automatic closing. Ventilation openings with an area of not less than 1% of the horizontal cross-section shall be provided at the top of the shaft. A drainage sump with a capacity of not less than 2 m³ shall be provided at the bottom of the fire elevator shaft, and the drainage pump flow rate shall not be less than 10 L/s. The waterproofing grade of the pit shall not be lower than P6, with a dual waterproofing layer of flexible plus rigid waterproofing.
Common shaft problems include undersized dimensions, excessive verticality deviation, incorrect ring beam positions, insufficient machine room space, and pit water accumulation. To solve undersized dimensions, non-standard cars or shallow pit solutions shall be adopted, with additional customization costs of approximately RMB 50,000 to 150,000. When the verticality seriously exceeds the limit, rework is required. For incorrect ring beam positions, steel structure brackets shall be added for transition, increasing the cost by approximately RMB 2,000 to 5,000 per location.
Shaft maintenance focuses on guide rail lubrication status, guide shoe wear, wire rope tension consistency, governor rope status, and buffer integrity. The shaft lighting illuminance shall not be less than 50 lux, and a comprehensive inspection shall be carried out once a year, including shaft wall cracking and water seepage, loose guide rail brackets, load-bearing beam deformation, and pit water accumulation.
To improve shaft design quality, it is recommended to finalize the elevator model at the civil construction drawing stage. Shaft dimensions shall be reserved with margin to facilitate elevator brand replacement later. Sufficient maintenance space shall be reserved in the machine room layout, and a lifting hook shall be reserved above the traction machine for later replacement of the traction machine. The overhead height and pit depth shall meet the minimum requirements of GB 7588 with a safety margin of 100 to 200 mm. For super high-rise buildings, intermediate maintenance platforms shall be considered inside the shaft to facilitate inspection and maintenance of wire ropes and compensation chains. The embedded steel plates for guide rail brackets in the shaft shall be accurately positioned with a deviation controlled within ±10 mm to ensure that the guide rail installation accuracy meets the requirements for smooth elevator operation.
From the perspective of engineering practice, common problems in shaft design often stem from insufficient coordination at the design stage. It is recommended to organize the elevator manufacturer to conduct a joint design review of shaft coordination at the early stage of design, clarifying the shaft dimensions, ring beam positions, load-bearing beam layout, and machine room space requirements. Verticality detection during shaft construction shall be taken as a key quality control point, with detection and recording carried out after the completion of each floor. The shaft acceptance before elevator installation shall include three steps: dimension re-check, verticality detection, and ring beam position confirmation; any non-conforming item shall be rectified before installation.
Cost optimization in shaft design shall be carried out on the premise of ensuring safety. For example, reasonably optimizing the ring beam spacing while meeting code requirements can reduce concrete consumption and construction costs. For the design of load-bearing beams, steel beams can be used instead of concrete beams, which both reduces the cross-section and facilitates construction. However, these optimization schemes must be reviewed and confirmed by structural engineers to ensure that the safety and stability of the shaft structure are not reduced. The waterproofing and drainage design of the shaft pit is an easily overlooked aspect; water seepage in the pit will cause moisture damage to elevator electrical components and, in severe cases, even lead to failure of safety devices. It is recommended that pit waterproofing adopt a dual waterproofing scheme of structural self-waterproofing plus coating waterproofing, and that automatic drainage pumps be provided to start drainage automatically when accumulated water reaches the set water level. Shaft lighting and maintenance sockets shall be provided strictly in accordance with the code to ensure the safety and convenience of maintenance personnel working in the shaft.
Quality control of shaft construction is the foundation of the elevator installation project, and a floor-by-floor verticality detection record shall be established during construction. After the completion of each floor, a laser plummet instrument shall be used to detect the verticality deviation at the four corners and midpoints of the shaft; the detection data shall be entered into the construction log and compared with the design allowable deviation. For locations where the verticality deviation exceeds the limit, the rectification plan and responsible person shall be marked, and re-detection shall be carried out after rectification until qualified. The concrete pouring of shaft ring beams shall be vibrated densely, the ring beam surface shall be flat without honeycomb or pitting, and the positions of the reserved embedded steel plates for guide rail brackets shall be precisely controlled within ±10 mm. After the reinforced concrete pouring of the shaft walls is completed, standard curing shall be carried out for 28 days, during which no holes shall be cut in the shaft walls. Holes that must be cut shall be drilled with a water drill and structurally strengthened in accordance with regulations. The traction machine may be installed only after the concrete strength of the load-bearing beam at the top of the shaft reaches 100% of the design strength. The waterproofing construction of the shaft pit shall be carried out after the structure below ground is completed; after the waterproofing layer is completed, a water storage test of not less than 24 hours shall be carried out, and it is qualified when no leakage is found after the water level reaches the design level. The fire drainage pipes in the shaft shall be embedded at the pit construction stage, and the slope and diameter of the drainage pipes shall meet code requirements. The ventilation design of the shaft shall consider the heat generated by elevator operation and the air flow in the shaft; insufficient ventilation opening area will cause the temperature in the shaft to rise and affect the normal operation of elevator equipment. It is recommended to provide ventilation openings at both the top and bottom of the shaft to form natural convection, combined with mechanical ventilation devices to enhance ventilation and heat dissipation during high summer temperatures. Shaft lighting shall use moisture-proof and dust-proof LED luminaires with an illuminance of not less than 50 lux, and the installation positions of the luminaires shall avoid the travel paths of the guide rails and the car. Shaft maintenance sockets shall use waterproof sockets with leakage protection to facilitate the use of power tools by maintenance personnel.
Quality control of shaft construction is the foundation of elevator installation engineering, and floor-by-floor verticality inspection records should be established during construction. After each floor is completed, a laser plummet should be used to inspect the verticality deviation at the four corners and midpoints of the shaft; the inspection data should be entered into the construction log and compared with the design allowable deviation. For locations where the verticality deviation exceeds the standard, the rectification plan and responsible person should be marked, and re-inspection should be carried out after rectification is completed until compliance is achieved. Concrete pouring for the shaft ring beams should be vibrated densely, the ring beam surfaces should be flat without honeycomb or pitting, and the positions of embedded steel plates reserved for guide rail brackets should be accurately controlled within ±10 mm. After the reinforced concrete pouring of the shaft walls is completed, 28-day standard curing should be carried out, and during the curing period, holes must not be cut in the shaft walls. Where holes must be cut, water drills should be used and structural reinforcement should be carried out in accordance with regulations. The traction machine may be installed only after the concrete strength of the load-bearing beam at the top of the shaft reaches 100% of the design strength. Waterproofing construction in the shaft pit should be carried out after the underground structure is completed, and after the waterproofing layer is completed, a water accumulation test of no less than 24 hours should be conducted. Fire protection drainage pipes in the shaft should be embedded during the pit construction stage, and the slope and diameter of the drainage pipes should meet code requirements. The ventilation design of the shaft should consider the heat generated by elevator operation and the air flow within the shaft; insufficient ventilation opening area will cause the temperature in the shaft to rise and affect the normal operation of elevator equipment. It is recommended to set ventilation openings at both the top and bottom of the shaft to form natural convection. Shaft lighting should use moisture-proof and dust-proof LED luminaires, with illuminance not less than 50 lux. Shaft maintenance sockets should use waterproof sockets with leakage protection. Through standardized and strict shaft construction quality control, a good foundation is laid for the safe and smooth operation of elevators.
The common quality problems in shaft construction and their treatment plans need to be mastered by engineering management personnel. When the shaft size is too small, the design drawings should first be verified to confirm whether the minimum requirements are met; if they cannot be met, non-standard elevator cars should be selected or the shaft structure should be adjusted. When the shaft verticality exceeds the standard, the cause of the deviation should be analyzed and corresponding corrective measures taken; if the deviation is within a controllable range, it can be compensated by adjusting guide rail bracket shims, and if the deviation seriously exceeds the standard, rework should be carried out. When the position of the shaft ring beam does not match the design, steel structure brackets should be added for transitional treatment. When water accumulates in the shaft pit, the integrity of the waterproofing layer and the smoothness of the drainage system should be checked, and plugging and dredging measures should be taken. Quality management of shaft construction should establish a three-level inspection system: self-inspection by the construction team, re-inspection by the supervision unit, and final inspection by the construction unit. Inspection records after each process is completed should be signed and confirmed and archived for future reference. Change management in shaft construction is equally important; any change to shaft dimensions and structure should be confirmed by the design unit and a change notice issued. Before implementation of the change, technical disclosure should be conducted for all employees to ensure accurate execution of the change content. Finished product protection in shaft construction should include anti-rust treatment of embedded parts, temporary sealing of reserved holes, and dust protection of equipment in the shaft.