Structural assessment for high concrete pier with a vertical construction error and suggestion of the improvement measurement

Slip-form construction is a construction method for tall structures, such as buildings, bridges, towers, offshore platforms and dams, in which concrete is poured into a continuously moving form. These forms serve as supporting walls strong enough to bear the concrete weight poured over top of it. Slip-form has been used for the construction of tall piers of long span bridges not only to reduce the construction period but also to ensure the safety The slip-form method, however, sometimes has showed several problems, such as vertical errors under construction or deflections of forms, from irregular loads by construction materials, workers or its weight, or unsettled friction or bond between concrete and forms. These include, but not limited to, problems in mechanical and hydraulic operations due to greater weight of steel form, problems in ensuring that the slip-form remains plumb i.e. the horizontal deviations do not exceed specified limits and certain other handling problems arising due to the weight of the form itself. This paper presents a case of construction errors that aroused during vertical slip-forming in the construction of bridge pier using steel as the slip-form. Moreover, it also includes field inspection, shape survey, structural assessment through the structural analysis and the measures taken against these errors. The most reasonable causes of these construction errors that may occur were estimated to weight and friction force of steel form. So, using of FRP form was suggested which is efficient in reduction of weight and friction force, therefore proving to be an excellent alternative to the steel slip-form