Strengthening of the beam

Engineering survey

Beijing Yanqing No. 1 middle school canteen is composed of one paragraph and two sections. A two-story brick-concrete structure was built by the Yanqing County Construction Committee in 1998, and the second was a concrete frame structure built in 2005. In 2008, Beijing Zhufu Construction Affairs Co., Ltd. carried out seismic appraisal of the canteen, determined that the project does not meet the requirements of earthquake resistance, put forward a reinforcement plan for the canteen. One section of the brick-concrete structure, the northern canteen operating room part of the wall plate reinforcement, beam reinforcement using bonded steel plate, column reinforcement using enlarged cross-section, reinforcement design service life of 40 years. Two-storey frame structure, columns are strengthened by outer-wrapped steel, beams are strengthened by bonded steel plate, and the design life is 50 years. After the construction space is insufficient, can not be constructed, instead of FRP fabric reinforcement, the canteen seismic reinforcement and transformation construction is to use the school during the summer vacation, on June 30, 2010, September 1, 2010, the canteen as scheduled for students to cook, September 15, 2010, all completed.

Reinforcement range

The construction area of this project is 3117.85 square meters, of which the wall plate reinforcement is 560 square meters, enlarged section reinforcement is 63 square meters, the beam bonded steel reinforcement is 890 square meters, FRP fabric reinforcement is 260 square meters, the outer steel reinforcement is 410 square meters.

Principle of bonded steel plate reinforcement

Bonded steel reinforcement is to use structural adhesive steel plate to reinforce or enhance the strength of the concrete structure and improve the safety of the structure. The steel plate and the concrete stress component work together, so that the original steel, strength are greatly improved, especially the durability and fatigue resistance. For example, if a hole is made in the wall, the side wall of the hole can be glued with steel to play the role of a hidden column, and the surface of the beam-slab horizontal structure can be glued with steel to increase the effect of the trabecula.

This method has little influence on production and life, and has no significant influence on the appearance of the original structure and the original clearance. When the structure of negative bending distance section of frame joint is difficult to deal with, local adjustment method is often used to stick the bottom of beam first. It is suitable for strengthening bending or tension members under static load and in service environment with temperature not exceeding 5-60 degrees C, relative humidity not exceeding 70% and no chemical corrosion. If not, effective protective measures should be taken.

Types and methods of sticking steel plate

Reinforcement of beams

One section is a brick concrete structure, and the main beam and side beam are reinforced by four sides. That is to say, the U-shaped hoop of the beam is glued to the floor at the bottom of the beam and then glued to the beam after the structural glue is firmly completed, and then glued to the top of the beam (< beam width), and anchored with expansion bolts, all expansion bolts are plum-shaped distribution.

Beam reinforcement

In concrete structure, the beam is strengthened by U-shaped hoop and anchored by expansion bolt. All expansion bolts are plum-shaped.

Beam reinforcement at deformation joints

A section of 1-12 axis beam at the deformation joint was originally designed to be reinforced with U-shaped stirrups. Because the distance between the deformation joints is only 15 cm, the construction space is insufficient and the anchor bolt can not be constructed. After modification of the design, the U hoop of the deformation joint is reinforced with FRP fabric.