Bearing structures
- a set of structures of a building or structure that, statically interacting, withstand loads, ensure the strength and stability of the building. The remaining structures of the building are called enclosing (self-supporting).
The main structures that accept the loads occurring in the building constitute the load-bearing frame
, that is, a set of horizontal (floors) and vertical (walls, pillars, racks, columns, etc.) (sometimes inclined) structural elements. In addition to the frame, load-bearing structures include foundations (they take the loads of the load-bearing frame and distribute them to the base of the building, for example, to the load-bearing soil), stairs, and roofs (a flat roof is sometimes classified as a floor).
Load classification
The loads that load-bearing structures must resist are divided into:
- constant
- the dead weight of building structures and structures, soil pressure on the basement walls, as well as stationary enclosing structures, finishing and other materials; - temporary
(long-term and short-term) - loads from the weight of people, furniture, stationary equipment, property permanently located in the building (liquids, solids, gases), long-term temperature, snow and wind effects; - crane
- loads from braking of the crane trolley, movement and braking of the crane itself; - special (special)
- loads from explosions, accidents, settlement and subsidence of soil, seismic effects, vibration of equipment, etc.
Calculation
When calculating structures, you can be guided by different criteria and requirements. Until 1955, the USSR used calculations based on permissible stresses. The requirement was met that the designed structure with the smallest possible cross-section retained its strength. In fact, a single safety factor was applied to all structures, regardless of their method of use and operating conditions[1].
Since then, a method for calculating limit states has been used that takes into account the requirements of normal operation. This method takes into account three limit states (LS) depending on three requirements for structures [1].
- 1PS - according to load-bearing capacity. The calculation had to guarantee the strength, stability and endurance of the structure.
- 2PS - for deformation and displacement. For example, a ceiling can bend in such a way that it does not lose its strength, but from an operational point of view it will cause a number of problems, such as the destruction of enclosing structures, non-load-bearing walls, and partitions.
- 3PS - for crack resistance. The extent of crack opening is limited or their formation is prevented so that there is no threat to the operation of the structure due to loss of impermeability, corrosion of elements or local destruction.
The greatest loads, the occurrence of which will not disrupt operation, are called standard. The product of standard loads and the overload factor is called design loads[1].
Based on the classification of loads, all loads can act non-simultaneously. Therefore, the calculations take into account different combinations of loads (main, additional and special). The main combination includes all permanent loads, temporary long-term loads and one short-term load, which has the greatest impact. Additional combinations contain all long-term, temporary long-term and all short-term loads. In special combinations, one of the special loads is added[1].
Removing and installing rear body elements
content .. 180 181 182 183 184 185 186 187 188 189 ..Daewoo Matiz. Rear body
The fuel filler cap is attached to the fuel tank pocket on the left side of the vehicle.
Filler cap
Removal
Pull the cap release lever and open the fuel filler cap.
| Rice. 10.130. Filler neck: 1 - bolts; 2 - filler cap |
Unscrew bolts 1 () and remove cover 2 of the filler neck.
Installation
Install the filler cap and secure with bolts.
Fuel filler handle and cable
Removal
Lift the front lower sill trim panel.
Remove the fuel filler cap release handle in the following order:
| Rice. 10.131. Opening the filler cap: 1 - screws; 2 - cable; 3 — handle fastenings |
— unscrew screws 1 ();
— disconnect cable 2;
— remove handle 3 for opening the filler cap.
Lift the lower trim panel of the B-pillar.
Lift the rear lower sill trim panel.
Lift the trim panel of the spare wheel well in the luggage compartment.
| Rice. 10.132. Removing the locking loop (1) of the fuel filler neck |
By turning, remove the locking loop 1 () of the filler neck.
Remove the fuel filler opening cable in the following order:
— remove the cable tensioning tape;
| Rice. 10.133. Location on the vehicle of the cable (1) for opening the fuel filler cap |
— disconnect cable 1 () for opening the filler cap.
Installation
Connect the fuel filler cap opening cable to the cap.
Secure the cable with tightening tape.
Install the lock hinge.
Install the spare wheel well trim panel in the luggage compartment.
Install the rear lower body sill panel.
Install the lower B-pillar trim panel.
Connect the fuel filler cap opening cable to the handle.
Install the fuel filler cap opening handle and secure with screws.
Trunk door handle and cable
Removal
Lift the front lower sill trim panel.
Remove the trunk door release handle in the following order:
| Rice. 10.134. Removing the trunk door opening handle: 1 — screws; 2 - cable; 3 - handle |
— unscrew screws 1 ();
— disconnect cable 2;
— remove handle 3 for opening the trunk door.
Lift the lower trim panel of the B-pillar.
Lift the rear lower sill trim panel.
Lift the trim panel of the spare wheel well in the luggage compartment.
Disconnect the cable from the tailgate lock hinge.
Remove the tailgate release cable in the following order:
— remove the cable tensioning tape;
| Rice. 10.135. Location on the vehicle of the cable (1) for opening the trunk door |
— disconnect cable 1 () for opening the trunk door.
Installation
Connect the tailgate release cable to the lock loop.
Secure the cable with tape.
Install the spare wheel well trim panel in the luggage compartment.
Install the rear lower body sill panel.
Install the lower B-pillar trim panel.
Connect the tailgate release cable to the handle.
Install the tailgate release handle and secure with screws.
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Literature
- Team of authors Dr.
arch. prof. M. S. Tupolev, associate professor A. N. Shkinev, prof. A. N. Popov, Ph.D. arch. Assoc. A. A. Popov, Ph.D. tech. Assoc. Sc. Yu. L. Sopotsko, Ph.D. arch. Assoc. T. I. Kirillova, Ph.D. arch. V. N. Kartsev, Ph.D. arch. O. V. Koretko, engineer I. A. Braunsdorfer, Ph.D. tech. Sciences V.V. Bespalov, engineer V. M. Kunin. Constructions of civil buildings / edited by M. S. Tupolev, scientific editor - architect. G. A. Dovzhik. - Moscow: Construction Literature Publishing House, 1968. - 239 p. - S. I. Vaidman, L. F. Teverovsky, D. V. Yakovlev.
Building construction. - Leningrad: Publishing house of literature on construction, 1970. - 344 p.
Rice. 2. Device for checking wheel camber and kingpin angles Having achieved the installation of a level bubble with a scale of 7 against the zero division, determine the wheel camber angle on the scale and compare it with the required one.
To check the longitudinal and transverse angles of inclination of the kingpin, the steered wheels drive onto graduated turntables. Turn the wheels 20° to the right, brake them and install the device on the hub, as indicated above. Having loosened the screw, turn the device body relative to the ball joint of the stand so that the bubbles of both levels take place opposite the zero scale marks.
A mechanical stand for checking steering wheel alignment angles consists of a platform with a movable plate, a pedestal mounted at the same level with the platform, and a column with instruments. When a car hits the platform with one wheel and the other on the pedestal, the movable plate moves in the transverse direction under the action of lateral forces caused by the toe-in and camber of the wheels. Toe and camber are determined using instruments, the readings of which depend on the displacement of the slab.
To check the alignment angles of the steered wheels using an optical stand, a mirror reflector is attached to the car wheel. The directed light beam is reflected onto the scale of the stand microscope. The wheel alignment angles are determined by the displacement of the light spot on the scale.
The adjustment of the steering wheel hub bearings is checked by axial play in the bearing and ease of rotation of the wheel. After hanging the wheel, swing it by the tire in a direction perpendicular to the plane of rotation and determine the play. The ease of rotation of the wheel is checked by pushing it with your hand behind the tire. When rotating too hard, the brake pads may touch the surface of the drum. If this malfunction is not detected by inspection, then the cause of the wheel’s tight rotation may be incorrect adjustment or failure of the hub bearings. A sign of this malfunction is also heating of the hub when the car is moving. With proper adjustment of the bearings, the wheel should make at least 6...8 revolutions from a strong hand push.
The technical condition of wheels and tires is checked by inspection. The wheel rim should not have nicks, bends or dents. The holes in the disks for the fastening studs should not be worn out. There should be no objects stuck in the tires.
The height of the tread pattern, measured at the center of the treadmill, must be at least 1 mm. The difference in tread depth for tires mounted on dual wheels should not exceed 3 mm.
Methods for troubleshooting the carrier system. If the rivet connections of the frame are weakened, or if its elements are cracked or deformed, the frame must be repaired. Corrosion is removed by cleaning the affected areas and treating them with a corrosion converter. Places with damaged paint are tinted.
To eliminate axial movement of the towing hook, an additional gasket is installed between the support washers and the elastic element. The towbar nut should be threaded only as far as it will go into the support washer, but not tightened. After this, the nut is turned in the opposite direction until one of the slots on it aligns with the hole on the hook and pinned. In this case, the axial movement of the towing hook should not exceed 0.5 mm. An elastic rubber element that has lost elasticity or is worn out, as well as a towing hook that is worn by more than 5 mm, are replaced.
If the alignment angles of the steered wheels are violated, their toe-in is adjusted. To do this, loosen the tie rod end bolts and use a pipe wrench to rotate the rod: to increase toe forward, and to decrease it backward. Having completed the adjustment, tighten the nuts of the coupling bolts of the rod ends until they stop. The inclination of the kingpins and the camber of the wheels of trucks are not adjusted, but restored by replacing worn parts of the kingpin joint. If necessary, adjust the front axle beam.
To adjust the hub bearings of the steered wheels, the wheels are suspended. After removing the bearing cap and unscrewing the lock nut, loosen the nut by unscrewing it 1/4… 1/2 turn. Check the ease of rotation of the wheel. If there is tight rotation, its cause is determined and eliminated: brake pads sticking to the drum, oil seals sticking, or bearings are destroyed. Then smoothly tighten the nut until the wheel rotates tightly (the bearings begin to brake the hub). While tightening the nut, simultaneously turn the wheel so that the rollers are positioned correctly in the bearings. Then loosen nut 3 by 1/8… 1/4 turn until the pin aligns with the nearest hole in the lock washer. By tightening the locknut and bending the lock washer onto its edge, check the ease of rotation of the wheel.
To adjust the hub bearings, the rear wheels are suspended and the axle shaft is disconnected from the hub. Further actions are similar to those discussed above. The adjusting nut is secured with a locknut and a locking ring.
Damaged spring leaves, rubber bushings and buffers are replaced. Leaf springs that have lost their elasticity are sent for repair. The stepladder nuts securing the spring ears are tightened until the spring washers are compressed. Further tightening of the nuts is not recommended. When the lining of the sliding end of the main sheet wears out, remove it and continue to operate the car without it. When the crack 52 is worn in the contact area with the lining by more than half the wall thickness, it is rearranged so that it rests on the lining with the unworn part.
Wheel tires are usually recommended to be rotated periodically. However, it is difficult to disagree with O.V. Yaremenko*, who claims that as the tire gets used to the road, the pressure on individual tread protrusions decreases and the wear rate of the tire decreases. In addition, with a cross-shaped rearrangement, the wheel receives the opposite direction of rotation, which negatively affects the fatigue strength of the tire.
Dismantling and mounting of tires should be carried out on special stands. If the need for reassembly arises on the way, it is performed using mounting blades.
Maintenance of the carrier system. During EO, the condition of the springs, wheels and tires is checked by inspection; if necessary, the air pressure in the tires is brought to normal and foreign objects stuck in the tread and between the tires are removed.
During TO-1, the condition of the springs, shock absorbers and towbar is checked by inspection. If necessary, tighten the fastenings of the spring parts and eliminate the misalignment of the rear axle. Check and, if necessary, tighten the wheel nuts.
During TO-2, the angles of the steered wheels are checked and, if necessary, their toe-in is adjusted. If tires wear unevenly, the wheels are balanced. Check and, if necessary, adjust the clearances of the wheel hub bearings. Check the condition of the frame and its rivet connections.
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