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The precast pier body connects the protruding reinforcement in the pier body through the grouted metal corrugated pipe embedded in the cap beam or bearing cap.

The test results show that the pier constructed by precast and assembled connection of sleeve (Coupler) and bellows (Duct) has similar seismic performance compared with the traditional cast-in-place concrete pier, and can meet the requirements of expected seismic performance.

The structural features are high construction accuracy requirements, short time required for site construction, and no need for tensioning prestressed reinforcement.

Its mechanical properties under normal use conditions are similar to those of traditional cast-in-place concrete piers, so it has certain economic advantages.

The mechanical properties of piers constructed with this structure are often similar to those of traditional cast-in-situ concrete piers, but the existence of wet joints will increase the construction time and the amount of on-site reinforcement lapping and pouring.

The advantage is that the construction process is simple and the amount of on-site work is small; The disadvantage is that the mechanical behavior of the joint, especially the seismic performance, needs further study.

The insertion length is generally 1.2~1.5 times the section size of the pier body.

The main characteristics of precast piers and abutments are that they can be precast in the prefabrication yard with less interference from the surrounding environment, but relatively high requirements for transportation and lifting machinery and equipment.

The assembly joint is the key process, which should be firm, safe, and simple in structure for construction.

(3) Grouted metal corrugated pipe connection This connection structure is often used for the connection between the pier body and the bearing cap or between the pier body and the cap beam.

The precast assembled pier connected with bonded prestressed tendons has the same deformation capacity as the cast-in-place concrete pier, but the energy consumption capacity is weak.
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The construction process mainly includes precast components, installation connection and concrete joint filling.

At the same time, the on-site construction requires tensioning, grouting and other operations for the prestressed reinforcement.

The construction time of this structure is short, but it needs to meet the requirements of sufficient anchorage length of longitudinal reinforcement, and its mechanical properties are similar to those of traditional cast-in-place concrete piers.

For more highlights, please click the blue letters above to follow us! Source: With the development of external pre-stressing technology and the appearance of internal pre-stressing tendon corrosion and other problems, cast construction methods are becoming more and more popular in China.

The commonly used assembly joints are as follows: (1) The bonded post-tensioned prestressed reinforcement connection structure is often used to realize the construction of segmental precast piers with mortar cushion or epoxy adhesive joint structure.

The structural feature is that the prestressed reinforcement passes through the joint, which has many practical engineering applications, and the design theory, calculation analysis and construction technology experience are mature.

Based on the typical pier structure of the actual project, three precast and assembled connection modes of sleeve, corrugated pipe and bonded prestressed reinforcement are selected to carry out the scale test research on the low cycle repeated horizontal loading of the rectangular solid segment precast column.

(4) Slot connection The slot connection structure is shown in Figure 6, which has been applied in some bridge projects, mainly used for the connection between pier body and capping beam, pile and pile cap.

From the perspective of rapid construction, this scheme has some shortcomings.

(5) The reinforcement shall be welded or overlapped, and a certain amount of reinforcement shall be protruded in advance for the precast pier with wet joints to be overlapped with the reserved reinforcement of adjacent components.

The connection structure is adopted for the construction of Jishuitan Bridge in Beijing, China, and some bridges in the United States are also constructed with this connection structure.

From the application experience of foreign countries, low seismic risk areas have been widely used, and the application and scientific research of high seismic risk areas are still in progress.

(6) Socket connection The socket joint connection structure is to insert the precast pier body into the reserved hole corresponding to the foundation.

The disadvantage is that the cost of the pier body is much higher than that of the traditional cast-in-place concrete pier.

The construction process is complex and the construction time is long.

As shown in the figure.

In order to realize the comprehensive promotion and application of full precast assembly technology, it is necessary to carry out in-depth research on the seismic performance of precast columns.

At present, a few bridges in foreign countries have used this connection structure for construction, and it is rarely used in areas with high seismic risk, and its seismic performance is still under study.

Construction of precast pier and abutment The precast pier and abutment is to divide the tall pier and abutment into several components in the vertical direction, according to a certain modulus and level, and pour them on the precast site around the bridge site, transport them to the site by vehicle and ship, and lift them for assembly.

The contact surface between the pier body and the capping beam or cushion cap often uses the mortar cushion, and the pier body segments use the epoxy adhesive joint structure.

Through the quasi-static test and finite element numerical analysis of the segment precast column specimens under different construction details, the hysteretic characteristics of the segment precast column under different construction modes are studied Ductile deformation, nonlinear mechanical behavior at joints, damage and failure mechanism, etc.

(2) The grouting sleeve connects the precast pier body segments and connects the protruding reinforcement through the grouting connection sleeve.

Compared with grouting sleeve, metal bellows, etc., the advantage is that the required construction tolerance can be larger, and a certain amount of concrete needs to be poured on site.

The bottom is paved with a certain thickness of mortar, and the surrounding is filled with semi-dry hard concrete.

This is also the design idea of segmental pier which is widely used in China at present.

Fixing Socket Cross Hole Nail Plate

Temporary support shall be provided, and the connection part of reinforcement shall be connected by post-cast concrete (wet joints).

The prestressed reinforcement in the scheme can use high-strength steel bars such as stranded steel wire or finish rolled deformed steel.

Precast column pier is to decompose the pier into several components, such as cushion cap, column, capping beam (pier cap), etc., which are precast in the factory or on site, and then transported to the site for assembly.

The site workload is significantly reduced.

The contact surface between the pier body and the cap beam or bearing cap often uses the mortar cushion, and the epoxy adhesive joint structure is used between the pier body segments, as shown in Figure 5.

Seismic performance of precast columns The seismic performance of precast columns is a technical problem that hinders the application of full precast assembly technology in bridges in high seismic risk areas.