Brick buildings for seismic prone areas

House build with Wienerberger clay blocks which made it through a series of earthquakes without a single crack
House built with Wienerberger clay blocks in the Italian region of Emilia Romagna that withstood the earthquake in May 2012.

Earthquake-resistant construction

The main objective of earthquake-resistant construction is to protect people and buildings during seismic activities.

Earthquake-resistant construction covers a wide range of activities to design, outfit and/or renovate buildings to make them capable of withstanding earthquakes up to a specific magnitude.

Wienerberger, the world’s largest producer of bricks, has addressed this challenge and developed a variety of solutions for earthquake-prone areas. Among others, Wienerberger has been involved in international research projects on the dimensioning, design and construction of brickwork structures in seismically threatened zones. These many years of research led to the development of a number of products by Wienerberger, including a special type of brick whose properties make it particularly well-suited for earthquake-prone areas.

Porotherm seismic clay block

Extensive research formed the basis for Wienerberger‘s development of the so-called Porotherm seismic clay block.

The patented Porotherm seismic clay block is a special brick whose properties guarantee higher relevant masonry strength and make it particularly well suited for earthquake-prone areas. It has a specially shaped vertical mortar pocket with a unique mortar window that forms a tooth connection between the block and the mortar in the butt joint. This creates an excellent bond with the mortar and increases mechanical strength.

Buildings constructed with these clay blocks are substantially more resistant to the types of horizontal displacements that occur during an earthquake. This has been indicated by various analyses in the test series: “Seismic Test Program of special designed clay blocks due to earthquake resistance by Wienerberger consisting real scale shaking table-, cyclic shear-, diagonal tension- and compression tests“.
 
Another way of improving the earthquake-resistance of brick structures is so-called confined masonry of the type required, for example, in Croatia. In confined masonry construction, the masonry walls are confined by vertical reinforced concrete columns which are placed at regular intervals. The walls are built first and the concrete is poured either in channels of special purpose bricks or in channels left open between wall segments. The combination of these reinforced concrete columns with the brick masonry produces a structure that has optimal load-bearing capacity, above all during an earthquake. With confined masonry it is also safe to build multistory buildings in seismic prone areas.This type of brick masonry makes economical, safe and energy-efficient construction possible in areas with higher seismic activity. The particular form of masonry construction and the building configuration must be selected considering local requirements – just the same as with any other building material – and in line with the potential impact of an earthquake.

Shaking table tests on real scale buildings

We constantly develope and test our products, in order to provide the best quality and highest safety for our customers. A full-scale seismic testing of modern unreinforced insulation filled clay blocks, has been conducted in form of so called shaking table tests.
 
The requirements of clay block masonry building constructions changed drastically during the last decades. Besides mechanical strength, also thermal insulation is becoming more and more important. Following this trend Wienerberger has successfully developed a series of insulation filled clay blocks.

New product developments run through a series of tests concerning their strength. In order to test its loadbearing capacity under seismic events, Wienerberger initiated an applied research project together with external European experts. In the course of this research, shaking table tests on real scale buildings have been conducted, as these tests deliver most reliable results. 

For this purpose, two mock-ups with different geometries were tested on 3-D shaking tables, using a series of seismic records with increasing intensity. After analysing the data, comparative calculations and the comparison with current standards, the results have been reviewed, which confirmed the excellent performance of the products tested.

The results

Even after more than 50 shakes with increasing ground accelerations (seismic inputs), the buildings tested, showed excellent seismic behaviour. The strength of the two models was even higher than predicted by calculations that have been conducted before the tests. In conclusion, this research confirmed that insulation filled clay blocks can be used in seismic areas without hesitation and that - following the relevant standards – buildings constructed with Wienerberger insulation filled clay blocks provide safety even in the case of earthquakes.

For further information and technical details, the complete study and results of the full-scale seismic testing, can be downloaded below.

Software for dimensioning earthquake-resistant masonry

AmQuake is a result of a close cooperation between the software company Červenka Consulting and Wienerberger. The tool has been developed to help engineers design safe brick buildings for earthquake-prone regions in Europe.
 
The construction of stable buildings requires not only exact planning, but also extensive calculations. The most important parameters are provided by so-called Eurocodes – standardised design rules for construction in Europe. There are currently 10 Eurocodes, which are classified into 58 sections, as well as national annexes for each country . The introduction of the Eurocodes in the European Union increased demands on the seismic design of brickwork. These new regulations have led to higher safety standards for the construction industry and, at the same time, require engineers to use new methods and calculation procedures.
 
Eurocodes 6 and 8 play a key role in this process: Eurocode 6 covers the dimensioning and construction of masonry buildings, while Eurocode 8 defines the design rules for the design of building construction and civil engineering structures in seismic areas. The required calculations are complex and can only be performed in an economically feasible way with the use of special software. This situation led to a joint project by Wienerberger and Cervenka Consulting, a software company for special engineering solutions, to develop a programme that facilitates the application of Eurocodes 6 and 8. The goal was to provide optimal, user-friendly support for construction engineers and architects that uses the draft plan as input to calculate the design load and automatically computes the structural safety check.
 
AmQuake is based on the so-called push-over method and equivalent framework method. With a user-friendly graphic surface, it examines the seismic and static stability of masonry buildings. The use of realistic, non-linear calculation methods like the push-over method is permitted by Eurocode 8. This method allows engineers to calculate the dissipative properties of structures in a realistic way. At the same time, the complexity of the calculation remains within acceptable limits. The AmQuake software is currently available for national standards of Austria, Belgium, Bulgaria, Croatia, Czech Republic, France, Germany, Hungary, Romania, Slovakia and Slovenia. Further information can be found on the AmQuake website and factsheet.

Wienerberger brick buildings are stable

In Italy, buildings constructed with Wienerberger bricks have withstood earthquakes in recent years with no signs of damage.The proof is provided by analyses carried out after the last earthquake in the north Italian region of Emilia Romagna. 

Without a doubt, Italy has been hit harder than any other European country by earthquakes in recent years. A disastrous quake struck L’Aquila in the Abruzzi region during 2009, and the Emilia Romagna region in Northern Italy was shaken in 2012. Many buildings, including numerous historical structures, were damaged or destroyed.

After the earthquakes, Wienerberger located and evaluated the buildings that were constructed with modern Wienerberger bricks according to state-of-the-art technical standards and in line with applicable regulations. All of these six buildings, including four close to the epicentre, withstood the earthquake in May 2012 with no signs of damage.

The condition of the buildings was evaluated by experts on behalf of the Italian brick association “Andil“, with studies carried out on these buildings after the earthquake. Find the Italian download below. The results demonstrate that earthquake-resistant construction with Wienerberger bricks is not only a theoretical possibility, but also a well-proven reality.

Related expertise articles