[First in Malaysia] CIDB CREAM Certified MOMENT Mechanical Splicing System

With all these catastrophes all around the world, Malaysia has been exposed to the stark reality that we can no longer be considered immune to such tragedies of tragic proportions in terms of lives lost, property destruction and even economic collapse.

The government and regulatory bodies have therefore taken serious steps in reviewing current building regulations and codes, to enable structural engineers and constructors to take immediate and necessary precautions to ensure the safety of their design as they are liable if anything happened to the buildings (refer provisions under CIDB act below).

*MS 2500 (Profile) Enforced 1 December 2016 Consultation with industry and testing body on 5 January 2017: Testing requirements for design requirements are not clearly stated. The meeting agreed to adopt AS4600 and EN9590 Part 5 in addition to MS2500. CIDB has submitted the MS2500 revise application to DSM on January 6, 2017.

MOMENT JT mechanical connections conform fully with applicable codes including BS 8110 Pt 1:1997 Clause 3.12.8.16.2 Bar in Tension and ISO 15835, providing defined ductile behaviour and performing like a continuous reinforcing bar.

Fig 1: MOMENT JT connections perform beyond the yield point of the bar whereas Lap Splices are only defined in the elastic area. This indicates that the MOMENT JT connection which works as a continuous bar provides additional strength and safety all around independent of the quality of the surrounding concrete.

In reinforced concrete design, the Structural Engineer is faced with the task of determining where and how reinforcing bars must be spliced in a structure. This must be done to ensure that the national regulations are adhered to and also to make sure that the structure will not suffer a progressive collapse if overloaded.

Due to the minimum connection strength required, it is generally assumed in design that the occurrence of a mechanical connection of two reinforcing bars does not result in a reduction of the anticipated structural strength nor the longitudinal ductility of the reinforcing steel. This would maintain the properties which the reinforced concrete member would have had with a continuous unspliced bar. That is, it is assumed that the use of a mechanical connection does not introduce a structural weakness that could jeopardize the overall structural performance.

Design requirements of the applicable codes as in BS 8110 and EN 1992-1 generally assume a minimum connection strength but are silent on the details about test methods and conformity assessment. ISO 15835, which is used as the basis for CREAM’s assessment covers all aspects of coupler production and assessment including:

1. To assess the serviceability, a test is made on a representative gauge length assembly comprising reinforcement of the size, grade and profile to be used and a coupler of the precise type to be used, the permanent elongation after loading to 0.6fy should not exceed 0.10mm,
2. It also covers tests for couplers to be used for mechanical splices in reinforced concrete structures under predominantly static loads and additional requirements for couplers to be used in structures subjected to high cycle elastic fatigue loading and/or to low cycle elastic-plastic reverse loading to represent seismic activities.

In a structure undergoing inelastic deformations during an earthquake, the tensile stresses in reinforcements may approach the tensile strength of the reinforcements. The requirements for MOMENT JT mechanical splices are intended to avoid a splice failure when the reinforcement is subjected to expected stress levels in the plastic regions. In addition to that, in plastic hinge regions, the first part to fail is the concrete where excessive spalling occurs. Once the concrete spalls, the lap splice behaviour is severely compromised, whereas the mechanical splice behaviour remains intact.

Lap Splices (2011 – Turkey) – Concrete spalling results in lower or zero capacity as the concrete that is critical in the load transfer has disappeared.

Mechanical Splices (2017 – Mexico City) – Concrete spalling has no effect on capacity as the mechanical connection is still present.

In seismic consideration:

1. MOMENT JT connections promote full strength capabilities and offer in tension more than the specified ultimate strength of the reinforcing bars ensuring that rupture will only occur in the reinforcing bar before failure in the mechanical connection.
2. MOMENT JT connections are manufactured to the exact standards to withstand a breaking strength of more than 700MPa  thereby promoting adequate strength and ductility so that failure initiates in the concrete rather than the steel reinforcements in the event potential inelastic straining may occur during seismic excitation.

MOMENT JT connection offers many advantages to the designer and builder to help improve the design and reduce construction time and cost while providing versatility and can help to solve many construction problems today.

As Malaysia progresses in nation-building, federal governance, regulations and codes for construction regarding seismic frame construction become more stringent, MOMENT JT connections, the proven mechanical splice method, provides you with the ability to design and build concrete structures to withstand the test of time.

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